What sizes does this cover?

The Socket & Wrench Size pack covers standard metric hex bolts from M3 to M36 and imperial hex bolts from 1/4" to 1-1/2". These are the most common sizes in hardware stores and automotive work.

Are these sizes guaranteed correct?

Sizes are based on ISO and SAE standards for standard hex head bolts and nuts. Actual fasteners vary by manufacturer, grade, and application. Always verify with the fastener when precision matters.

What about Torx, spline, or specialty fasteners?

This tool covers hex head fasteners only. Torx, spline, 12-point, and other drive types are not yet supported.

Can I use the nearest imperial socket on a metric bolt?

In a pinch it may work, but risks rounding the fastener head. Use the correct socket whenever possible. Related values shown are for reference, not substitution.

Will more packs be added?

Yes. Pilot Hole, Tap Drill, and Metric/Imperial conversion packs are planned. The architecture supports new reference sets without changing the app.

21mm → 13/16" Imperial

The nearest imperial equivalent of 21mm is 13/16" (0.36mm difference).

Result

Answer

13/16" (20.64mm)

Standard

Buy21mm socket SAE conversion set Metric + SAE combo set

Input Size21mm

Nearest Imperial13/16" (20.64mm)

Difference0.36mm

Second Nearest7/8" (22.23mm, 1.23mm off)

SystemMetric → Imperial

A 21mm socket or wrench is closest to 13/16" imperial (20.64mm), a difference of 0.36mm. Close enough for most jobs, but use the correct size when precision matters.

Note

Reference value from published fastener data. Always verify with the fastener manufacturer for critical applications.

Related Sizes

← 20mm 22mm →

About 21mm Conversion

A 21mm metric socket or wrench is closest to 13/16" imperial (20.64mm), with a difference of 0.36mm. The sizes are close enough for most applications, but always use the correct metric socket when precision matters. The second-nearest imperial size is 7/8" (22.23mm, 1.23mm off). Lug nuts, automotive. When working on mixed metric and imperial fasteners, a combination socket set covers both systems and eliminates guesswork.

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