Wheel Offset Calculator
How much a new offset moves the wheel in or out.
Enter your values
Enter the stock wheel width in in.
Enter the stock offset in mm.
Enter the new wheel width in in.
Enter the new offset in mm.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Moves outward
- 22.7 mm
- Moves inward
- 2.7 mm
- New backspacing
- 6.38 in
- Clearance check
- Inner clearance similar to stock
Quick answer
Changing offset moves the wheel by the offset difference; changing width adds half the extra width to each side of the wheel.
Outward change = (Δwidth ÷ 2) − Δoffset
At a glance
| What it does | How much a new offset moves the wheel in or out. |
|---|---|
| Category | Auto |
| Inputs needed | Stock wheel width, Stock offset, New wheel width, New offset |
| Main output | Moves outward |
| Formula | Outward change = (Δwidth ÷ 2) − Δoffset |
| Cost | Free — no sign-up, no download |
How to use the Wheel Offset Calculator
- 1Enter the stock wheel width in inches and the offset stamped on the wheel (ET number).
- 2Enter the new wheel width and offset.
- 3Check outward movement against your fender gap.
Inputs explained
- Stock wheel width(in)
- Enter the stock wheel width in in.
- Stock offset(mm)
- Enter the stock offset in mm.
- New wheel width(in)
- Enter the new wheel width in in.
- New offset(mm)
- Enter the new offset in mm.
Worked example
Using the values the calculator loads with:
Inputs
- Stock wheel width8 in
- Stock offset45 mm
- New wheel width9 in
- New offset35 mm
Results
- Moves outward22.7 mm
- Moves inward2.7 mm
- New backspacing6.38 in
- Clearance checkInner clearance similar to stock
Frequently asked questions
What is a negative offset?
A negative offset puts the mounting face behind the wheel centreline, pushing the wheel outward for a deep-dish, wider-track look.
How much poke is safe?
Anything past the fender line risks tire rub, curb damage and, in many regions, a failed inspection. Keep the tire inside the arch at full lock.
What do I need to enter into the Wheel Offset Calculator?
Just 4 values: stock wheel width, stock offset, new wheel width, new offset. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Wheel Offset Calculator work out the answer?
Changing offset moves the wheel by the offset difference; changing width adds half the extra width to each side of the wheel. It applies the formula Outward change = (Δwidth ÷ 2) − Δoffset and shows the working so you can check each step by hand.
Is the Wheel Offset Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.