How to use a torque wrench: click, beam and digital, accuracy and calibration
Set the wrench, hold it at the center of the grip, and pull slowly and steadily until it clicks or reads the value, then stop. A typical click wrench is accurate to ±4%, which is the ISO 6789-2 limit, and should be recalibrated every year or 5,000 cycles, whichever comes first. Never use it to break loose a stuck fastener.
Contents8 sections
Key takeaways
- ISO 6789 splits hand torque tools into indicating (Type I: dial, beam, digital) and setting (Type II: click) 1.
- The ISO 6789-2:2017 maximum permissible deviation is 4% 2; TEKTON's click wrench is calibrated to ±4% 3.
- Calibration intervals in national and international standards are one year or 5,000 cycles, whichever comes first 4.
- Pull slowly and smoothly, stop at the click, and don't use the wrench to break stuck fasteners 3.
- Store a click wrench at its lowest setting to relieve the spring 3.
Quick facts
| Typical accuracy | ±4% of reading 3 |
|---|---|
| Recalibration | 12 months or 5,000 cycles 4 |
| Calibration device accuracy | Within ±1% of reading 4 |
| Direction | Most click wrenches measure clockwise only 3 |
The three common types
ISO 6789, the international standard for hand torque tools, divides them into two kinds: indicating torque tools (Type I) and setting torque tools (Type II) 1.
- Click wrenches (setting, Type II). You set the torque on a scale before use. When the setting is reached the mechanism releases with a click you hear and feel 3. Norbar notes that even used correctly, the torque actually applied can differ from the scale value because of manufacturing tolerances, which is what calibration checks 4.
- Beam and dial wrenches (indicating, Type I). A pointer or dial shows the torque as you pull. Honda’s cylinder head bolt procedure for the 2013 Odyssey and Pilot specifies a beam-type torque wrench for the torque stage 5.
- Digital wrenches (indicating, Type I). An electronic display shows the torque being applied 4. The accuracy table reproduced in NASA RP-1228 rates digital torque wrenches at ±1/4 to 1% of full scale, against ±3 to 15% for bar torque wrenches in general 6.
How to tighten with a click wrench
These steps follow TEKTON’s operator’s manual for its 1/2 in. drive click wrench 3, with the calibration notes from Norbar 4.
Set the value
Unlock the handle, turn it to the main-scale mark, then add the micrometer divisions. On TEKTON’s 25 to 250 ft-lb wrench each micrometer mark is 1 ft-lb. Lock the handle. Norbar adds that a setting should always be approached from below: if you wind past it, go back down and come up again 4.
Fit the socket and run the fastener down
Use the wrench like a ratchet until the fastener is snug.
Hold the grip
Grasp the knurled handle only 3. Calibration loads the wrench at the center of the handle or at the maker’s marked load point 4.
Pull slowly and steadily
As the fastener becomes snug, slow to a smooth, steady pull. Pulling too fast or too hard can carry you past the setting 3.
Stop at the click
Release the handle at the instant it clicks. Pulling on after the click overtightens the fastener and can damage the wrench 3.
Pull clockwise
TEKTON’s wrench measures torque in the clockwise direction only 3. Check your own wrench before torquing left-hand threads.
At low settings the click is subtle. TEKTON suggests a quiet place and extra care to release at the click 3.
Accuracy: what ±4% means
ISO 6789-2:2017 sets a maximum permissible deviation of 4% for click and peak wrenches, checked with five readings 2. TEKTON ships its wrench calibrated to ±4% 3. On a 100 ft-lb setting, the wrench may deliver anywhere from 96 to 104 ft-lb and still be in specification.
That is small next to the friction effect. Even a perfect torque produces a clamp load that varies by about ±25% 6 (see torque vs tension). A wrench out of calibration by 10% adds to that.
Stay inside the range. TEKTON’s wrench “does not measure torque below 25 ft.-lb.” 3, the bottom of its 25 to 250 ft-lb scale. Norbar notes that calibration testers themselves are typically usable from 10% to 100% of their range 4. For small fasteners, use a smaller wrench rather than the bottom of a big one.
Calibration
Norbar: “Calibration intervals set by national and international standards are either one year or 5000 cycles, whichever comes first. This may be too long for safety critical operations and more frequent calibration may be necessary” 4. Subaru’s head bolt bulletin asks for a calibration check if the torque wrench or angle gauge hasn’t been calibrated at least once in the prior 6 months 7.
A proper calibration, per Norbar’s summary of ISO 6789 4:
- is done at controlled temperature and humidity, with a calibration device accurate to ±1% of reading;
- loads the wrench horizontally, or vertically in a vertical plane, never laid flat and pushed down;
- exercises a setting wrench five times before readings, and takes five readings at each test point.
Recheck sooner after abuse. NASA-STD-5020B: if a tool may have been knocked out of calibration “such as dropping, impact, or other damage”, confirm the calibration is still valid before use 8. Torque checkers at the workplace give a quick go/no-go check between calibrations, but they are not a calibration 4.
Care and storage
- Store at the lowest setting. TEKTON: storing at 25 ft-lb “relieves extra tension on the internal spring, eliminating fatigue that can adversely affect accuracy.” Don’t turn the handle below the lowest setting 3.
- Exercise it after storage. If the wrench hasn’t been used for a long time, operate it several times at a low setting so the internal lubricant recoats the parts 3.
- Keep it dry and clean. Wipe with a dry cloth. Don’t immerse it in liquid or cleaner 3.
What not to do
- Don’t use it as a breaker bar. “Do not use wrench to break free stuck fasteners” 3. Loosen with a breaker bar, tighten with the torque wrench.
- Don’t add leverage. TEKTON: “Do not attempt to increase leverage of this wrench with any other device” 3. Honda’s owner’s manual warns against over-tightening wheel nuts “using your foot or a pipe” 9.
- Don’t add a crowfoot without correcting. An offset adapter changes the torque at the fastener. A straight extension does not 10. Use the extension calculator.
- Don’t confuse in-lb and ft-lb. Dual-scale wrenches print ft-lb and N·m on opposite sides of the handle 3. Check which scale you’re reading. The converter handles the arithmetic.
- Don’t guess angle steps. Torque-plus-angle procedures need a torque angle gauge as well as the torque wrench 7. See torque-to-yield bolts.
Sources
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- 4Norbar Torque Tools, The Checking and Calibration of Torque WrenchesChecked 21 Oct 2026
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Spotted a value that doesn’t match its source? Report an error
Related
- Extension calculatorFind the torque wrench setting with a crowfoot or adapter: T_set = T × L ÷ (L + E). 100 ft-lb through a 2 in adapter on an 18 in wrench means setting 90.
- Torque converterConvert torque between ft-lb, in-lb, N·m, kgf·m, kgf·cm and ozf·in. 1 ft-lb = 1.355818 N·m and 1 kgf·m = 9.80665 N·m, from NIST SP 811.
- Torque vs tensionTorque only estimates bolt tension: about 90% goes into friction, so preload scatters ±25% or more. The figures from NASA-STD-5020B, NASA RP-1228, Fastenal and RCSC.
- Lug nut tighteningTighten lug nuts in a star pattern, in two passes, on clean dry studs, then re-check when your manual says: 25 miles for Ram, 100 for Ford, 600 for Nissan.