Estimate flat washer weight from outside diameter, inside diameter, thickness and material density in metric or imperial units. Quantity is optional (blank means one). Inverse mode finds thickness from single-piece weight. Density presets are approximate; alloy, coatings and manufacturing tolerances affect actual mass.

Uniform flat annulus estimate. Density presets are approximate; actual alloy, coatings, chamfers and tolerances affect mass.

Zero models a solid disk.

Editable; choosing a material replaces this value.

Optional settings

Blank = one washer.

Flat Washer Weight Formula

The following formula is used to calculate the Flat Washer Weight. 

FWW = pi × (OD² / 4 - ID² / 4) × T × d

Variables:

  • FWW is the Flat Washer Weight (lbs)
  • OD is the washer outer diameter (in) 
  • ID is the washer inner diameter (in) 
  • T is the washer thickness (in) 
  • d is the material density (lbs/in^3)

How to Calculate Flat Washer Weight?

The following two example problems outline the steps and information needed to calculate the Flat Washer Weight.

Example Problem #1

  1. First, determine the washer outer diameter (in).
    • The washer outer diameter (in) is calculated to be 10.
  2. Next, determine the washer inner diameter (in).
    • The washer inner diameter (in) is measured to be 5.
  3. Next, determine the washer thickness (in).
    • The washer thickness (in) is found to be 2.
  4. Next, determine the density.
    • Assume carbon steel at approximately 0.2836 lb/in³ (about 7.85 g/cm³).
  5. Finally, calculate the Flat Washer Weight using the formula above: 

FWW = pi*(OD^2/4 – ID^2/4) * T * d

The values provided above are inserted into the equation below and computed.

FWW = π/4 × (10² − 5²) × 2 × 0.2836 ≈ 33.41084 lb for one washer.

Example Problem #2

The variables required for this problem are provided below:

washer outer diameter (in) = 30

washer inner diameter (in) = 20

washer thickness (in) = 5; assumed density = 0.2836 lb/in³

Test your knowledge and check your answer with the calculator.

FWW = π/4 × (30² − 20²) × 5 × 0.2836 ≈ 556.84730 lb for one washer. Multiply single-piece mass by quantity for a batch. Inverse mode uses a known single-piece mass to solve thickness.