Fork Oil Level Calculator
Calculate fork oil volume and air gap for suspension tuning.
Inputs
mm
mm
mm
lb
Results
Oil per Leg
435.7 mL
Total Oil Needed
871.4 mL
≈ 2 soda cans
Air Gap Volume158.4 mL
Adjusted Oil Level120 mm
Level Adjustment0 mm
Recommended Viscosity10W
How to Use This Calculator
- Enter Fork Tube Inner Diameter, Fork Tube Length, and Oil Level (from top).
- Select Oil Viscosity (5W, 10W, 15W, or 20W) and enter Rider Weight.
- Review Oil per Leg (mL) and Total Oil Needed (mL).
- Use Air Gap Volume (mL), Adjusted Oil Level (mm), and Recommended Viscosity to fine-tune the setup for your weight.
How the result changes with Fork Tube Inner Diameter
| Fork Tube Inner Diameter | Oil per Leg | Total Oil Needed |
|---|---|---|
| 29 | 218 mL | 436 mL |
| 37 | 354.8 mL | 709.6 mL |
| 48 | 597.2 mL | 1,194.4 mL |
| 57 | 842.1 mL | 1,684.2 mL |
What each input means
- Fork Tube Inner Diameter
- Inner diameter of the fork tube (check service manual).
- Fork Tube Length
- Total internal length of the fork tube.
- Oil Level (from top)
- Distance from top of fork to oil surface with fork fully compressed and spring removed.
- Oil Viscosity
- Fork oil weight (higher = stiffer damping).
- Rider Weight
- Rider weight for personalized adjustment.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersFork Tube Inner Diameter = 41, Fork Tube Length = 450, Oil Level (from top) = 120, Oil Viscosity = 10 = 5 input(s) provided
- Calculate Oil per Leg435.7 = 435.7
- Calculate Total Oil Needed871.4 = 871.4
- Calculate Air Gap Volume158.4 = 158.4
- Calculate Adjusted Oil LevelAdjusted Oil Level120 = 120
Engine last updated . Checked against 3 independently-derived tests — how we verify calculators.
Related Calculators
The questions that sit next to this one — chosen by subject, including calculators filed under a different category.
More in Automotive & Motorcycles.