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Washers · ISO 7089 / ISO 7093

M18 Flat Washers Dimensions & Specifications

M18 Flat Washers Dimensions & Specifications reference image

M18 Flat Washers (ISO 7089 / ISO 7093) are specified by thread size, length and head dimensions. The M18 row from the standard is reproduced below, followed by the drill sizes, spanner size and torque values used when installing this size.

M18 Dimensional Row (ISO 7089 / ISO 7093)

For bolt sizeInner diameter d1 min (mm)Outer diameter d2 max (mm)Thickness h (mm)Reference standard
M1819.034.03.0ISO 7089

Spanner & Drive for M18 Flat Washers

Drive geometry for M18 Flat Washers is given by the row above; match the tool to the listed values.

Common Applications for M18 Flat Washers

M18 Flat Washers are commonly specified for high-load load-spreading on structural joints.

Installation Tips for M18 Flat Washers

  • At M18 the stretch in the bolt becomes the controlling factor — for critical joints, use angle-controlled or stretch-controlled tightening instead of pure torque.

Mating Parts for M18

A M18 flat washer pairs with a M18 bolt/screw and matching M18 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.

Request a Quote

Adjust the parameters in the drawing above and click "Request this configuration" to send the exact specification straight to this form.

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Specification
Business Information

Dimensions & Specifications (ISO 7089 / ISO 7093)

For bolt sizeInner diameter d1 min (mm)Outer diameter d2 max (mm)Thickness h (mm)Reference standard
M1.61.74.00.3ISO 7089
M22.25.00.3ISO 7089
M2.52.76.00.5ISO 7089
M33.27.00.5ISO 7089
M3.53.78.00.5ISO 7089
M44.39.00.8ISO 7089
M55.310.01.0ISO 7089
M66.412.01.6ISO 7089
M77.414.01.6ISO 7089
M88.416.01.6ISO 7089
M1010.520.02.0ISO 7089
M1213.024.02.5ISO 7089
M1415.028.02.5ISO 7089
M1617.030.03.0ISO 7089
M1819.034.03.0ISO 7089
M2021.037.03.0ISO 7089
M2223.039.03.0ISO 7089
M2425.044.04.0ISO 7089
M2728.050.04.0ISO 7089
M3031.056.04.0ISO 7089
M3334.060.05.0ISO 7089
M3637.066.05.0ISO 7089
M3940.072.06.0ISO 7089
M4243.078.07.0ISO 7089
M4546.085.07.0ISO 7089
M4850.092.08.0ISO 7089
M5254.098.08.0ISO 7089
M5658.0105.09.0ISO 7089
M6062.0110.09.0ISO 7089
M6466.0115.09.0ISO 7089
M55.315.01.0ISO 7093 large series
M66.418.01.6ISO 7093 large series
M88.424.02.0ISO 7093 large series
M1010.530.02.5ISO 7093 large series
M1213.037.03.0ISO 7093 large series
M1617.050.03.0ISO 7093 large series
M2021.060.04.0ISO 7093 large series
M2425.072.05.0ISO 7093 large series

Frequently Asked Questions

What grip range is typical for M18 structural bolts?

Grip ranges are highly application-dependent at M18. As a guide, choose a length that gives at least 1× the thread diameter engagement in the nut plus 2–3 thread pitches projecting.

Which washer dimensions matter most for M18?

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 M18 for Flat Washers?

For M18 the standard coarse pitch is 2.5 mm — this is the value used for Flat Washers.

What clearance and tapping drill suit M18?

Use a 20 mm clearance hole (ISO 273 medium) for through-fixing, or a 15.5 mm tapping drill for a coarse M18 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.