20mm → 13/16" Imperial
The nearest imperial equivalent of 20mm is 13/16" (0.64mm difference).
A 20mm socket or wrench is closest to 13/16" imperial (20.64mm), a difference of 0.64mm. The gap is significant — using the imperial size risks rounding the fastener. Use the correct metric socket.
The 0.64mm difference may cause the socket to slip or round the fastener head. Use the correct metric size whenever possible.
Related Sizes
About 20mm Conversion
A 20mm metric socket or wrench is closest to 13/16" imperial (20.64mm), with a difference of 0.64mm. The gap between sizes is significant — using the imperial substitute risks rounding the fastener head. Always use the correct metric socket. The second-nearest imperial size is 3/4" (19.05mm, 0.95mm off). Industrial fasteners. When working on mixed metric and imperial fasteners, a combination socket set covers both systems and eliminates guesswork.