M12 General Flat Washer (GB/T 97.1 / ISO 7089): the row from the product table, what the nominal bolt size controls in the assembly, and the notes that matter when specifying this size.
M12 Dimensional Row (GB/T 97.1 / ISO 7089)
For bolt size
Inner diameter d1 (mm)
Outer diameter d2 (mm)
Thickness t (mm)
Reference standard
M12
13.0
24.0
2.5
ISO 7089 / GB/T 97.1
Common Applications for M12 General Flat Washer — GB/T 97.1 / ISO 7089 (Series 087)
M12 General Flat Washer — GB/T 97.1 / ISO 7089 (Series 087) are commonly specified for medium-duty structural joints.
Mating Parts for M12
A M12 flat washer pairs with a M12 bolt/screw and matching M12 nut.
Technical Drawing
Customize the parameters below — every spec field is editable, and the drawing redraws to match the values you choose. Changing the size will snap the other fields to that size's standard values; you can then override any individual value.
Sends the selected values to the quote form below.
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Dimensions & Specifications (GB/T 97.1 / ISO 7089)
For bolt size
Inner diameter d1 (mm)
Outer diameter d2 (mm)
Thickness t (mm)
Reference standard
M3
3.2
7.0
0.5
ISO 7089 / GB/T 97.1
M4
4.3
9.0
0.8
ISO 7089 / GB/T 97.1
M5
5.3
10.0
1.0
ISO 7089 / GB/T 97.1
M6
6.4
12.0
1.6
ISO 7089 / GB/T 97.1
M8
8.4
16.0
1.6
ISO 7089 / GB/T 97.1
M10
10.5
20.0
2.0
ISO 7089 / GB/T 97.1
M12
13.0
24.0
2.5
ISO 7089 / GB/T 97.1
M14
15.0
28.0
2.5
ISO 7089 / GB/T 97.1
M16
17.0
30.0
3.0
ISO 7089 / GB/T 97.1
M18
19.0
34.0
3.0
ISO 7089 / GB/T 97.1
M20
21.0
37.0
3.0
ISO 7089 / GB/T 97.1
M24
25.0
44.0
4.0
ISO 7089 / GB/T 97.1
M30
31.0
56.0
4.0
ISO 7089 / GB/T 97.1
M36
37.0
66.0
5.0
ISO 7089 / GB/T 97.1
Materials & Grades
Select a material class to see the grades we supply it in. Each designation is listed with its ISO/EN, AISI/SAE, JIS and GB equivalents.
Third-party video, selected automatically for this topic. It is not produced by Engineering Hardware and is not a specification source — use the tables on this page for dimensional data.
Inside the plant
Manufactured in our own plant
This part is cold-formed, threaded, heat-treated and finished in-house. The stages below are where its class and finish are actually decided.
01
Cold heading
Wire rod is drawn to size and cold-formed into blanks. Forming rather than cutting keeps the grain flow continuous around the head, which is where a bolt is most likely to fail.
Head dimensions and under-head radius checked at set-up and per shift.
02
Thread rolling
Threads are rolled between hardened dies rather than cut. Rolled threads are stronger in fatigue than cut threads and hold pitch and flank angle far more consistently across a batch.
Go / no-go ring gauges to ISO 965 tolerance class 6g.
03
Heat treatment
Quench-and-temper brings carbon and alloy steel to the property class ordered — 8.8, 10.9 or 12.9 — with the furnace charge tracked so a finished lot can be traced back to it.
Core hardness and tensile tested per lot to ISO 898-1.
04
Surface treatment
Zinc, zinc-nickel, hot-dip galvanizing, black oxide, phosphate and Dacromet, selected against the service environment rather than against the price list.
Coating thickness and neutral salt spray hours to ISO 9227.
Frequently Asked Questions
Which washer dimensions matter most for M12?
For a flat washer, the outside diameter (the bearing surface) and the thickness control how the load is spread under the head and how much elastic preload is preserved. The inside diameter must clear the bolt body but not be so large that the head bears mostly on the washer's outer rim.
What is the coarse-thread pitch of M12 for General Flat Washer — GB/T 97.1 / ISO 7089 (Series 087)?
For M12 the standard coarse pitch is 1.75 mm — this is the value used for General Flat Washer — GB/T 97.1 / ISO 7089 (Series 087).
What clearance and tapping drill suit M12?
Use a 13.5 mm clearance hole (ISO 273 medium) for through-fixing, or a 10.2 mm tapping drill for a coarse M12 thread.
How do I request a quotation?
Use the technical drawing on this page to pick the exact configuration, then submit it with the quote form. We respond within one business day.
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