METRIC FLAT WASHER DIMENSIONS

Metric Flat Washer Dimensions are shown in the following chart according to ANSI B18.22M and various ISO standards. Metric flat washer dimensions for nominal washer size from 1.6 mm to 64 mm are covered in the chart.

Some important notes from the ANSI B18.22M:

- Two types of washers are specified in the ANSI standard, Soft and Hardened. Soft washers are generally used in low strength applications to distribute bearing load, to provide a uniform bearing surface, and to prevent damage of the work surface. Hardened washers are intended primarily for use in high-strength joints to minimize embedment, to provide a uniform bearing surface, and to bridge large clearance holes and slots.

Some important notes from the ISO standards:

An overview of suitable combinations of ISO metric plain (flat) washers and bolts, screws or nuts in respect of property (hardness) classes and product grades is given in the following chart.

Washers Hardness class 100 HV 200 HV 300 HV
Product grade C A A
Bolts, screws, nuts Product grade A no yes yes
B no yes yes
C yes no no
Bolts, screws Property class ≤ 6.8 yes yes yes
8.8 no yes yes
9.8, 10.9 no no yes
12.9 no no no
Nuts Property class ≤ 6 yes yes yes
8 no yes yes
9, 10 no no yes
12 no no no
Case-hardened thread rolling screws yes yes yes
Stainless - steel bolts, screws and nuts - yes -



Calculator:

INPUT PARAMETERS
Nominal flat washer size

 


Dimensions of Plain Washer
METRIC FLAT WASHERS ACCORDING TO ASME STANDARD
Washer
Size
Washer
Series
Standard Inside Dia (A) Outside Dia (B) Thickness (C)
Max Min Max Min Max Min
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Note 1: Dimensions are in mm.
Note 2: Nominal flat washer sizes are intended for use with comparable nominal screw or bolt sizes.
Note 3: The 18.80 / 18.28 and 25.40 / 24.88 mm outside diameters avoid washers which could be used in coin operated devices. [ANSI B18.22M]

METRIC FLAT WASHERS ACCORDING TO ISO STANDARDS
Washer
Size
Washer
Series
Product
Grade
Standard Inside Dia (A) Outside Dia (B) Thickness (C)
Max Min Max Min Nom Max Min
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--- --- --- --- --- --- --- --- --- ---
--- --- --- --- --- --- --- --- --- ---
--- --- --- --- --- --- --- --- --- ---
--- --- --- --- --- --- --- --- --- ---
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Note 1: Dimensions are in mm.
Note 2: Nominal flat washer sizes are intended for use with comparable nominal screw or bolt sizes.
Note 3: Normal-series, product-grade-A flat washers chamfered at the outside diameter are available for nominal thread diameters ranging from 5 mm to 64 mm inclusive. [ISO-7090]. For a selected nominal size, inside & outside diameters and thickness values for chamfered washer (ISO-7090) and non - chamfered washer (ISO 7089) are same .
Note 4: Nominal sizes available in this calculator are preferred dimensions given in ISO standards. For non-preferred dimensions, check ISO standards.

Definitions:

Product Grade A and Grade C: A tolerance system for ISO punched metric flat washers. Tolerances for Grade A and Grade C are given in the ISO 4759-3:2000 standard.

Reference:
  • ANSI B18.22M - 1981, Metric Plain Washers
  • ISO 887:2000, Plain Washers for Metric Bolts, Screws and Nuts for General Purposes - General Plan
  • ISO 7089:2000, Plain washers — Normal series — Product grade A
  • ISO 7090:2000, Plain washers, chamfered — Normal series — Product grade A
  • ISO 7091:2000, Plain washers — Normal series — Product grade C
  • ISO 7092:2000, Plain washers — Small series — Product grade A
  • ISO 7093-1:2000, Plain washers — Large series — Part 1: Product grade A
  • ISO 7093-2:2000, Plain washers — Large series — Part 2: Product grade C
  • ISO 7094:2000, Plain washers — Extra large series — Product grade C