Power Tool

Impact Wrench

Impact wrenches are socket-driven fastening tools that deliver repeated rotational impacts to loosen or tighten nuts and bolts under higher loads than typical impact-driver work.

Drive Sizes · Comparison · Applications · Articles

Impact wrench drive sizes

Square-drive size affects socket compatibility and usually tracks the scale of work the tool is intended to handle. Actual torque depends on the specific model.

Drive sizeTypical roleStrengthsTradeoffs
3/8 inchCompact automotive and assembly workSmaller sockets and easier accessLess heavy-duty than larger drives
1/2 inchGeneral automotive and workshop useBroad socket availabilityLarger than compact 3/8-inch tools
3/4 inchHeavy-duty fasteners and equipmentSuited to larger sockets and loadsHeavier for routine work
1 inchVery heavy equipment and industrial workLarge-drive capacityBulky and specialized

Impact wrench vs. breaker bar vs. impact driver

All three can be involved in fastening work, but they apply force differently and use different interfaces.

ToolInterfaceTypical useControl
Impact wrenchSquare drive and impact-rated socketsRapid loosening and tightening of nuts and boltsFast and powerful; final torque may still require a torque wrench
Breaker barSquare drive and socketManual leverage for stubborn fastenersDirect manual feel
Impact driverQuick-change hex colletScrews and lighter compatible fasteningCompact but not a substitute for socket-focused work

Common applications

For fasteners with a specified final torque, follow the manufacturer procedure and use a calibrated torque wrench when required.

Impact Wrench articles

Drive sizes and torque

Tool and brand comparisons

Automotive use