top of page

ISO 13934-1
Maximum Force and Elongation of Fabrics: Strip Method

Universal Grip ISO 13934-1 fabric strip specimen cutting die

Downloads: ISO 13934-1 Fabric Strip Specimen Cutting Die – Universal Grip Data Sheet (PDF)

Written by Chris Thomas, Universal Grip Company · Reviewed by Frank Bertini · Updated October 24, 2026

ISO 13934-1 is the international strip method for the tensile properties of woven fabrics: a strip of defined width is gripped across its full width and extended at a constant rate until it ruptures, and the maximum force and the elongation at maximum force are reported in the warp and weft directions. It is the method behind most European and Asian fabric specifications for apparel, upholstery, workwear, airbags, sailcloth and technical textiles, the sibling of the ISO 13934-2 grab method, and the ISO counterpart of ASTM D5035.

This guide covers the current edition, ISO 13934-1:2013, and its scope, which includes the stretch wovens that one major equipment page wrongly excludes; the ravelled strip and the cut strip and how to prepare each; the 200 and 100 mm gauge lengths and the 20 and 100 mm/min rates with the elongation bands that decide them; the 2, 5 and 10 N pretension by mass per unit area and the slack-mounting alternative for elastic fabrics; the jaw faces, slip and jaw-break rules; conditioning to ISO 139; a worked example with the rounding rules; the common errors; a four-way comparison with ISO 13934-2, ASTM D5035 and ASTM D5034; and the cutting dies, grips and machines Universal Grip supplies for the test.

In this guide: What ISO 13934-1 Covers and What It Does Not · Editions and Adoptions · Specimens: Ravelled Strip, Cut Strip and the 20-Yarn Rule · Gauge Length, Test Speed and Pretension · Jaw Faces, Slip and the Jaw-Break Rule · Conditioning to ISO 139 · Step-by-Step Procedure · Calculation, Rounding and a Worked Example · Common Errors and How Much They Cost · ISO 13934-1 vs ISO 13934-2 vs ASTM D5035 vs ASTM D5034 · Equipment for ISO 13934-1 from Universal Grip · FAQ

What ISO 13934-1 Covers and What It Does Not

ISO 13934-1 applies to woven textile fabrics, including those with elastic yarns and stretch constructions, tested either conditioned or wet, on a constant-rate-of-extension (CRE) machine only. The standard says it is not normally applied to geotextiles, nonwovens, coated fabrics, glass-fibre fabrics or fabrics made from carbon or polyolefin tape, each of which has its own method: ISO 10319 for geotextiles, ISO 9073-3 for nonwovens and ISO 1421 for coated fabrics. Knitted fabrics are not excluded by name, but their high extension and tendency to curl make the strip method impractical, and most knit specifications use a grab or a bursting test instead.

  • Maximum force, Fmax: the highest force recorded as the strip is extended to rupture, in newtons, for a strip of 50 mm effective width. The standard does not convert to N/cm or stress; the width is fixed so the force is the property.

  • Elongation at maximum force: the increase in length at Fmax expressed as a percentage of the gauge length. This is the headline elongation; elongation at rupture may be reported in addition if required, and the two differ for fabrics that continue to extend as individual yarns fail.

  • Direction: both are reported separately for warp (machine direction) and weft (cross direction); a fabric is not characterised by one number.

The introduction of the standard states that results from the strip method should not be compared with results from the grab method or any other tensile method. A strip loads every yarn across its width; a grab loads the centre 25 mm and the surrounding fabric shares the load through the weave, so grab forces are lower and depend on the construction. Our textile testing page explains where each method is used.

Editions and Adoptions

ISO 13934-1 was first published in 1999, prepared by CEN under the Vienna Agreement so that EN ISO 13934-1 and the ISO text are identical. The current second edition, ISO 13934-1:2013, was a minor revision and was reviewed and confirmed in 2024, so there is no newer edition to wait for. The companion grab method is ISO 13934-2:2014, confirmed in 2025. National adoptions carry the same numbers: BS EN ISO 13934-1, DIN EN ISO 13934-1, GB/T 3923.1 and JIS L 1096 Method A (which references the ISO text for the strip method). The older German strip method DIN 53857 that still appears in some supplier specifications is superseded.

Specimens: Ravelled Strip, Cut Strip and the 20-Yarn Rule

The strip has an effective width of 50 ± 0.5 mm and is long enough to span the 200 mm gauge length plus the grip engagement at each end, which in practice means 250 to 300 mm. Two kinds of strip are defined:

  • Ravelled strip: the standard specimen for fabrics that can be frayed. The blank is cut wider than 50 mm and yarns are removed from both long edges until the effective width is 50 ± 0.5 mm with the edges parallel. For general wovens cut about 5 mm (or 15 yarns) extra per side, so a 60 mm blank; for loosely woven fabrics cut about 10 mm extra per side. Ravelling removes the cut yarns that would otherwise carry partial load and fray during the test, and leaves a strip whose width is defined by whole yarns.

  • Cut strip: for fabrics that cannot be ravelled, felted or heavily finished constructions and the thin coated textiles that are tested to this method by agreement. The blank is cut to 50 ± 0.5 mm with clean, parallel edges; a sharp die in a press gives a better edge than a rotary cutter or scissors.

  • The 20-yarn rule: the strip must contain at least 20 yarns across its width. A very coarse fabric with fewer than 20 yarns in 50 mm needs a wider strip, cut and ravelled to a width that contains 20 yarns, and the width is reported.

  • Number and position: at least five specimens in the warp direction and five in the weft, more if a higher confidence is required or the coefficient of variation is high. Specimens are taken at least 150 mm from the selvedge, and no two specimens in the same direction contain the same longitudinal yarns; the standard's annex shows the staggered cutting pattern that achieves this.

  • Wet specimens: cut at least twice the length so that one half is tested dry and the other wet; immerse the wet half in grade 3 water (ISO 3696) at 20 ± 2 °C for at least one hour, with up to 1 g/L of non-ionic wetting agent if needed, and test immediately after removal.

Width error goes straight into the result: a strip ravelled to 50.5 mm instead of 50.0 mm carries 1 % more yarns and reads about 1 % high, which is the whole width tolerance. The Universal Grip strip cutting die below cuts a square, parallel-sided blank in one stroke so that the ravelling starts from a true edge.

Gauge Length, Test Speed and Pretension

ISO 13934-1 sets the gauge length and rate together from the fabric's elongation at maximum force, which is found in a preliminary test. The logic is a constant nominal strain rate: 10 %/min for low-extension fabrics, 50 %/min for most apparel and upholstery wovens, and 100 %/min for stretch fabrics.

  • Elongation at Fmax under 8 %: gauge length 200 ± 1 mm, rate 20 mm/min (10 %/min). Typical of glass-reinforced, aramid, sailcloth and tightly woven polyester technical fabrics.

  • Elongation 8 to 75 %: gauge length 200 ± 1 mm, rate 100 mm/min (50 %/min). Most cotton, polyester-cotton, wool and nylon wovens.

  • Elongation over 75 %: gauge length 100 ± 1 mm, rate 100 mm/min (100 %/min). Elastane-containing stretch wovens; the shorter gauge keeps the crosshead travel and the test time reasonable.

  • Tolerances: rate within ± 10 %, gauge length set within ± 1 mm, maximum-force accuracy ± 1 % (ISO 7500-1 class 1), data acquisition at 8 Hz or faster so that the force peak is captured, not clipped.

Pretension sets the zero of the elongation measurement. For non-elastic fabrics it is chosen by the fabric's mass per unit area: 2 N for fabrics up to 200 g/m², 5 N for over 200 to 500 g/m², and 10 N for over 500 g/m²; the pretension must not extend the fabric by more than 5 %. Elongation is then measured from the pretensioned length. For elastic fabrics a pretension of 0.5 N is used or the strip is mounted slack and the elongation is taken from the point at which the force reaches the pretension value on the curve. Wet specimens use half the dry pretension. A fabric mounted with no pretension at all reads an elongation that includes the slack and the crimp take-up, which is why two laboratories can disagree by several percentage points on the same cloth.

Jaw Faces, Slip and the Jaw-Break Rule

The grips are the part of the strip test that decides whether the result is valid. The standard requires jaw faces that are smooth and flat, at least 60 mm wide and not narrower than the specimen, so that the whole 50 mm strip is clamped across its width with margin either side. Faces that are engraved, wave-profiled or packed with paper or medium-grit emery cloth are permitted where smooth faces cannot hold the fabric to rupture; the choice must be reported and kept constant within a series.

  • Slip: if the strip slips asymmetrically at the clamping line, or by more than 2 mm in total, the result is discarded. Mark the strip at the jaw edge before the test and read the slip afterwards.

  • Jaw break: a rupture within 5 mm of the clamping line is a jaw break. Jaw breaks are recorded; a jaw-break result may be retained if it is higher than the lowest normal break, otherwise it is discarded and a further specimen tested. Five valid breaks per direction are required.

  • Pressure: pneumatic grips at 4 to 6 bar with smooth or rubber faces hold most apparel wovens; heavy technical fabrics and high-tenacity yarns need wave or serrated faces or higher pressure. Too much pressure crushes the yarns at the jaw edge and causes jaw breaks; too little lets the strip slip.

  • Alignment: the strip is clamped square so that its long axis coincides with the load axis; a strip clamped at an angle loads the yarns on one side first and reads low.

Our grip selection guide and the textile testing post cover face choice and pressure in more depth; the video below shows quick-change jaw inserts being swapped between smooth and wave faces.

Conditioning to ISO 139

Specimens are relaxed and conditioned in the ISO 139 standard atmosphere, 20 ± 2 °C and 65 ± 4 % relative humidity, for at least 24 hours (longer for heavy or tightly woven fabrics until successive weighings agree) and tested in the same atmosphere. This is the textile atmosphere, not the plastics atmosphere of 23 °C / 50 % used by ISO 527-1 and ISO 1421 tests on coated fabrics, and the difference matters: cotton and viscose gain strength as they take up moisture, so a cotton strip conditioned at 50 % RH can read 5 to 10 % below the same strip at 65 % RH. Wet specimens need no pre-conditioning. ISO 139 also allows an alternative atmosphere of 23 °C / 50 % by agreement, which must be stated in the report.

Step-by-Step Procedure

  • 1. Preliminary test on a spare strip in each direction to find the elongation band and hence the gauge length and rate.

  • 2. Cut blanks about 60 × 260 mm (wider for loose weaves) at least 150 mm from the selvedge in the staggered pattern, at least five warp and five weft; cut strips at 50 ± 0.5 mm for fabrics that cannot be ravelled.

  • 3. Ravel each blank to an effective width of 50 ± 0.5 mm by removing roughly equal numbers of yarns from each side, checking that at least 20 yarns remain and the edges are parallel.

  • 4. Condition at 20 °C / 65 % RH for at least 24 hours; for wet tests, immerse the wet half for at least one hour.

  • 5. Set the gauge length to 200 ± 1 mm (100 ± 1 mm for elongation over 75 %) and the rate to 20 or 100 mm/min; fit smooth flat faces at least 60 mm wide.

  • 6. Mount the strip centrally and square in the upper jaw, apply the pretension (2, 5 or 10 N by mass per unit area; 0.5 N or slack for elastic fabrics; half for wet), close the lower jaw, and zero the extension.

  • 7. Run to rupture, recording force and extension at 8 Hz or faster.

  • 8. Check each specimen for slip (reject if asymmetric or over 2 mm) and for jaw break (within 5 mm of the clamping line); replace rejected specimens until five valid results per direction are obtained.

  • 9. Calculate the mean maximum force and mean elongation at maximum force per direction, with the coefficient of variation and, if required, the 95 % confidence limits; apply the rounding rules below.

  • 10. Report the edition, fabric identification, direction, specimen type (ravelled or cut), gauge length, rate, pretension or slack mounting, jaw faces, atmosphere, number of specimens, jaw breaks and slips, and the results.

Calculation, Rounding and a Worked Example

Maximum force is read directly in newtons. Elongation at maximum force E = (ΔL at Fmax ÷ L0) × 100, where L0 is the gauge length (200 or 100 mm) from the pretensioned or, for slack mounting, the pretension-crossing position. The standard rounds the mean maximum force to 1 N below 100 N, 10 N from 100 to 1,000 N and 100 N above 1,000 N, and the mean elongation to 0.2 % below 8 %, 0.5 % from 8 to 75 % and 1 % above 75 %. The coefficient of variation is given to 0.1 %.

  • Worked example (cotton sheeting, 145 g/m², warp): preliminary test shows about 17 % elongation, so 200 mm gauge, 100 mm/min, 2 N pretension. Five valid results: 412, 428, 435, 419 and 448 N with extensions at Fmax of 33.2, 34.8, 35.6, 33.9 and 36.1 mm.

  • Mean force: (412 + 428 + 435 + 419 + 448) ÷ 5 = 2,142 ÷ 5 = 428.4 N → rounded to 430 N (10 N step in the 100 to 1,000 N band).

  • Elongation per specimen: 33.2 ÷ 200 × 100 = 16.6 %; 17.4 %; 17.8 %; 16.95 %; 18.05 %. Mean = 86.8 ÷ 5 = 17.36 % → rounded to 17.5 % (0.5 % step in the 8 to 75 % band).

  • Coefficient of variation of force: standard deviation = 14.3 N; CV = 14.3 ÷ 428.4 × 100 = 3.3 %. The 95 % confidence limit for five results is ± 2.78 × 14.3 ÷ √5 = ± 17.8 N, so the mean is 428 ± 18 N.

  • Load cell: 448 N on a 5 kN cell is 9 % of range, fine; on a 1 kN cell it is 45 %, better. A denim at 1,200 N or a polyester technical fabric at 3,000 N per 50 mm wants the 5 kN cell.

  • Time check: at 100 mm/min a strip reaching Fmax at 36 mm extension takes about 22 s; at 20 mm/min a glass fabric reaching 3 % (6 mm) takes 18 s. Both are inside the sensible 10 to 60 s window that keeps rate effects small.

Common Errors and How Much They Cost

  • Testing a cut strip when a ravelled strip is required. The cut yarns along the edges carry partial load and fray; a cut strip of a ravellable fabric typically reads 2 to 5 % high and scatters more.

  • No pretension or the wrong pretension. Elongation measured from a slack start includes crimp take-up; the error is several percentage points on a 15 % fabric. Use 2/5/10 N by g/m², or the slack-mount rule for elastic fabrics.

  • Gauge length chosen from elongation at break. The criterion is elongation at maximum force. A fabric with 70 % elongation at Fmax but 80 % at rupture still uses the 200 mm gauge.

  • Jaw faces narrower than 60 mm. A 50 mm strip in 50 mm faces has no margin; edge yarns are clamped unevenly and jaw breaks follow. Use faces of 60 mm or wider.

  • Over-clamping. Serrated faces at full line pressure cut the yarns at the jaw edge; jaw breaks above 25 % of specimens mean the faces or the pressure must change.

  • Slow data rate. At 10 Hz or below the force peak of a brittle technical fabric is clipped; sample at 50 Hz or more.

  • Comparing strip with grab or with ASTM D5035. Different widths, gauge lengths and rates; results are not interchangeable (see below). Report the method with the number.

  • Conditioning at 23 °C / 50 %. This is the plastics atmosphere. Cellulosic fabrics read low by 5 to 10 % against the ISO 139 textile atmosphere of 20 °C / 65 %.

  • Two specimens on the same yarns. Specimens cut in line share warp (or weft) yarns and are not independent; use the staggered pattern.

ISO 13934-1 vs ISO 13934-2 vs ASTM D5035 vs ASTM D5034

The four fabric tensile methods a lab meets most often, with the numbers that differ. The ASTM figures match our ASTM D5035 strip test guide and ASTM D5034 grab test guide; the ISO 13934-2 figures are from the 2014 edition.

  • Specimen: ISO 13934-1 ravelled or cut strip, 50 ± 0.5 mm effective width, ≥ 20 yarns; ISO 13934-2 grab, 100 ± 2 mm wide with a line 38 mm from one edge; ASTM D5035 ravelled strip 25 mm (50 mm where 25 mm cannot hold 20 yarns) or cut strip 25 or 50 mm; ASTM D5034 grab 100 ± 1 mm wide, ≥ 150 mm long, line 37 ± 1 mm from the edge.

  • Jaws: ISO 13934-1 full-width flat faces ≥ 60 mm; ISO 13934-2 25 × 25 mm front face (25 × 50 permitted) gripping the centre; ASTM D5035 faces ≥ 10 mm wider than the strip and ≥ 25 mm high; ASTM D5034 25 ± 1 mm wide front jaw, 25 to 50 mm high.

  • Gauge length: ISO 13934-1 200 mm (100 mm over 75 % elongation); ISO 13934-2 100 mm (75 mm by agreement); ASTM D5035 75 ± 1 mm; ASTM D5034 75 ± 1 mm.

  • Rate: ISO 13934-1 20 or 100 mm/min by elongation band; ISO 13934-2 50 mm/min; ASTM D5035 300 ± 10 mm/min (or 20 ± 3 s to break for disputes); ASTM D5034 300 ± 10 mm/min.

  • Specimens: ISO 13934-1 ≥ 5 warp + ≥ 5 weft; ISO 13934-2 ≥ 5 per direction; ASTM D5035 and D5034 5 warp + 8 filling.

  • Pretension: ISO 13934-1 2/5/10 N by g/m² (0.5 N or slack for elastic); ISO 13934-2 same bands; ASTM methods no specified pretension (limited to 0.5 % of full scale).

  • Results: ISO maximum force (N) and elongation at maximum force (%); ASTM breaking force and apparent elongation. Strip force per 50 mm is roughly double the D5035 25 mm strip value for the same fabric but not exactly, because the extra yarns do not share load perfectly; grab force is lower than strip and the ratio depends on the weave.

  • Conditioning: ISO 139 20 ± 2 °C / 65 ± 4 % RH; ASTM D1776 21 ± 1 °C / 65 ± 2 % RH.

Equipment for ISO 13934-1 from Universal Grip

  • ISO 13934-1 fabric strip specimen cutting die (part UGC-ISO13934-SC): a rectangular strip cutting die with ejector plate, hardened and ground steel blade, and a rigid steel body that keeps the strip width consistent along the full length; 50 × 260 mm typical, custom sizes available. Sized for the strip method and suitable for hydraulic, pneumatic or manual cutting presses; for woven fabrics and thin coated textiles, confirm for heavy fabrics. Specify the strip width and length, fabric type and thickness, and the press when ordering. The 50 mm die cuts the cut strip for fabrics that cannot be ravelled; for the standard ravelled strip order the 60 mm variant (about 5 mm per side extra) and fray to 50 ± 0.5 mm. The 260 mm length gives the 200 mm gauge plus about 30 mm in each jaw.

  • Die press: a manual arbor press or a pneumatic press cuts apparel and upholstery wovens cleanly; dense technical fabrics and multiple layers need the hydraulic press.

  • Pneumatic grips with 60 mm and wider smooth, rubber and wave faces, 1 to 5 kN, with foot-pedal operation so both hands are free to align the strip; quick-change inserts let one grip run ISO 13934-1 strip, ISO 13934-2 grab (25 × 25 mm inserts) and ISO 1421.

  • Vise grips with 60 mm flat faces for low-volume or field laboratories.

  • Machines: apparel and upholstery fabrics rarely exceed 1 kN per 50 mm, so the Mark-10 testers and our 2.5 kN benchtop UTM cover them; denim, canvas and polyester technical fabrics at 1 to 3 kN use the 5 kN benchtop UTM with a 5 kN cell, which also runs the 100 mm/min rate to full travel for stretch wovens.

  • Video extensometers for laboratories that must report elongation from gauge marks rather than crosshead travel, for example when the fabric slips slightly in the jaws or a specification calls for a 100 mm reference length on the strip.

  • Environmental chambers for hot and cold tests on airbag, automotive and outdoor fabrics.

  • Related guides: ASTM D5035 strip, ASTM D5034 grab, ISO 1421 coated fabrics, ISO 2062 yarn tensile, our textiles page, and the ISO standards library.

ISO 13934-1 FAQ

What is the current edition of ISO 13934-1?

ISO 13934-1:2013, the second edition, a minor revision of the 1999 first edition. It was reviewed and confirmed in 2024 and remains current. EN ISO 13934-1, BS EN ISO 13934-1 and GB/T 3923.1 carry the same text.

What is the specimen width in ISO 13934-1?

An effective width of 50 ± 0.5 mm. A ravelled strip is cut about 60 mm wide (10 mm extra for loose weaves) and frayed to 50 mm with parallel edges; a cut strip for fabrics that cannot be ravelled is cut directly to 50 ± 0.5 mm. The strip must contain at least 20 yarns.

What gauge length and speed does ISO 13934-1 use?

200 ± 1 mm at 20 mm/min for fabrics with less than 8 % elongation at maximum force, 200 mm at 100 mm/min for 8 to 75 %, and 100 ± 1 mm at 100 mm/min for more than 75 %. The rate tolerance is ± 10 %.

What pretension does ISO 13934-1 specify?

2 N for fabrics up to 200 g/m², 5 N for over 200 to 500 g/m² and 10 N for over 500 g/m², provided the pretension extends the fabric by no more than 5 %. Elastic fabrics use 0.5 N or are mounted slack, and wet specimens use half the dry value.

How many specimens does ISO 13934-1 require?

At least five in the warp direction and five in the weft, cut at least 150 mm from the selvedge in a staggered pattern so no two share the same yarns, with five valid breaks per direction after rejecting slips and jaw breaks.

What counts as a jaw break or slip in ISO 13934-1?

A rupture within 5 mm of the clamping line is a jaw break; it is recorded and may be kept only if it exceeds the lowest normal break. A specimen that slips asymmetrically or by more than 2 mm at the jaw is discarded.

What jaw faces does ISO 13934-1 require?

Smooth, flat faces at least 60 mm wide and not narrower than the specimen. Engraved or wave faces, or paper or emery packing, are permitted when smooth faces cannot hold the fabric to rupture, and the choice must be reported.

How is elongation at maximum force calculated?

The extension at maximum force divided by the gauge length, times 100, measured from the pretensioned length (or from the pretension-crossing point for slack-mounted elastic fabrics). A strip extending 34.8 mm at Fmax on a 200 mm gauge has 17.4 % elongation.

What are the rounding rules in ISO 13934-1?

Mean maximum force to 1 N below 100 N, 10 N from 100 to 1,000 N and 100 N above 1,000 N; mean elongation to 0.2 % below 8 %, 0.5 % from 8 to 75 % and 1 % above 75 %; coefficient of variation to 0.1 %.

What conditioning does ISO 13934-1 use?

The ISO 139 textile atmosphere of 20 ± 2 °C and 65 ± 4 % relative humidity for at least 24 hours, with testing in the same atmosphere; 23 °C / 50 % only by agreement. Wet specimens are immersed in grade 3 water for at least one hour and need no pre-conditioning.

How does ISO 13934-1 differ from ISO 13934-2 and ASTM D5035?

ISO 13934-2 is the grab method: a 100 mm wide specimen held by 25 × 25 mm jaws over a 100 mm gauge at 50 mm/min, reporting maximum force only. ASTM D5035 is a strip method with a 25 mm (or 50 mm) strip, 75 mm gauge and 300 mm/min. Results from the three are not interchangeable.

What machine capacity is needed for ISO 13934-1?

Apparel and upholstery wovens give 200 to 1,000 N per 50 mm strip, denim and canvas 1 to 2 kN, and polyester or aramid technical fabrics 2 to 5 kN or more. A 2.5 kN single-column machine covers the first group and a 5 kN benchtop machine with 5 kN pneumatic grips covers most of the rest.

Need a strip cutting die, full-width fabric grips or a complete textile tensile system for ISO 13934-1? Contact Universal Grip with your fabric type, expected force and machine connection and we will quote the right setup.

bottom of page