How to choose the correct wrench size for a specific nut?

Size really does matter - especially when it comes to wrench sizes for nuts or bolts. This is especially true if you want to avoid damaging parts, tools, or even injuries.

If you're tired of trial and error, here's a handy chart that will help you quickly determine the correct size of flat/open-end or combination wrench for a specific bolt or nut head size:

Screw/nut size	wrench size (mm)
M1,6	3,2
M2	4
M2,5	5
M3	5,5
M3,5	6
M4	7
M5	8
M6	10
M7	11
M8	13
M10	17
M12	19
M14	22
M16	24
M18	27
M20	30
M22	32
M24	36
M27	41
M30	46
M33	50
M36	55
M39	60
M42	65
M45	70
M48	75
M52	80
M56	85

Other articles:
Jaké druhy klíčů známe?
Zástrčné klíče
Vytěráky vřetene
Co je vrták?

Indexable inserts for milling

03.01.2025

Indexable inserts for milling.

What types of wrenches do we know?

30.12.2024

Wrenches are among the basic equipment of both home and professional workshops, and many people might be confused by their names and which wrench to use on which nut. In this article, we will look at the basic types of wrenches.

How to choose a machine tap?

09.12.2024

Here we will discuss the basic information about choosing a machine tap.

Impact wrenches

03.12.2024

An impact wrench is an integral part of using industrial sockets. Therefore, they are intended for rough work, not for fine mechanics, because strength is their domain.

Cookie files

We use cookies to collect and analyze information about the performance and use of the website, to ensure the functioning of social media functions, and to improve and customize content and ads.