How to Measure Washers
Washer identification uses inside diameter, outside

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QUICK RULE
Washer identification uses inside diameter, outside
diameter, thickness and
material/hardness/specification.
THICKNESS
ID: inside hole diameter - nominal washer size is associated with bolt size, not necessarily
equal to measured ID.
OD: outside diameter.
THICKNESS: measure with calipers/micrometer.
TYPE: SAE, USS, F436 structural, F844/general, metric or specialty.
For structural work, hardness/specification is critical; do not substitute a soft commercial
washer by dimensions alone.
IDENTIFICATION ORDER
Product -> diameter -> thread -> length -> head/drive -> grade/material -> finish -> governing specification
REFERENCE ONLY. Verify the current ASME/SAE/ASTM/ISO/OEM standard and manufacturer data. Do not use as the sole basis for critical fastener selection or installation.
Fastener Guide reference FG-01E57F · thefastenerapp.com/fastener-guide/measure-and-identify/how-to-measure-washers · © The Fastener App. Reference only — verify the current governing standard, drawing and manufacturer data before specifying or installing.

























