Wheel Offset Calculator

This wheel offset calculator compares your current wheels to a new set. See how far the outer edge moves toward the fender (poke) and the inner edge toward the suspension, in millimeters and inches. Updates as you type.

How to read the result

• Poke is how much further the outer lip sits toward the fender. Positive means the new wheel sticks out more; negative means it tucks in.
• Inner edge is the suspension side. A positive number means the wheel moves closer to the strut, control arm or brake — the usual source of rubbing.
• Centerline shift is the offset difference alone. Lowering offset by 26 mm moves the whole wheel out 26 mm before width is considered.
• Backspacing is the distance from the mounting face to the inner lip — the number lift and off-road shops quote. Formula: width / 2 + 0.5 + offset ÷ 25.4.

What wheel offset means

Offset (often stamped ET, from the German Einpresstiefe) is the distance in millimeters between the wheel's mounting face and its centerline. Positive offset puts the mounting face toward the street side, so the wheel tucks inward. Negative offset pushes the wheel outward — the "deep dish" look on lifted trucks. Zero offset centers the mounting face.

Offset alone does not tell you where the edges are. A wider wheel at the same offset grows equally in both directions, so a 9-inch wheel at +18 sits very differently from a 7.5-inch at +18. That is why this tool compares both wheels.

Common gotchas when changing wheel offset

• Going from +44 to +18 on a wider wheel is a common truck upgrade and usually means 45 mm more poke — often more than a stock fender covers.
• Rubbing on the inside is the one people miss. Check the inner-edge number, not just poke.
• Wheel spacers add negative offset: a 25 mm spacer is the same as lowering offset by 25 mm.
• Tire width changes clearance too. This tool is wheel-only; a wider tire adds roughly half its extra width to each side.

Wheel offset chart: backspacing to offset

Shops quote backspacing in inches, wheels are stamped in offset (ET). This chart converts between the two for the common widths. Read down to your wheel width and across to its backspacing; the cell is the offset in millimeters.

Every cell is computed with the same formula as the calculator above: offset = (backspacing − width / 2 − 0.5) × 25.4.

Wheel offset questions

How do I calculate wheel offset?

Offset in mm = (backspacing in inches - width in inches / 2 - 0.5) x 25.4. An 8-inch wheel with 5 inches of backspacing is ET+13. The 0.5 accounts for the half inch of bead seat on each side that wheel widths leave out.

How many inches is a negative 44 offset?

ET-44 is 1.73 inches: the mounting face sits 1.73 inches inboard of the wheel's own centerline. That is not how far the wheel sticks out, because offset is measured from the centerline of that wheel, not from the hub of your vehicle.

What does +35 offset mean?

ET+35 means the mounting face sits 35 mm (1.38 inches) outboard of the wheel's centerline, toward the street side, so the wheel tucks in under the fender. Positive offsets in the +30 to +45 range are typical on front-wheel-drive cars.

How far will a 12 offset stick out in inches?

On its own, it does not: offset only has meaning against the wheel you are replacing. Swapping a same-width wheel from ET+35 to ET+12 moves it 0.91 inches (23 mm) further out. Divide the offset difference by 25.4 to get inches.

Is lower offset the same as a wheel spacer?

For the outer edge, yes: a 25 mm spacer moves the wheel out the same 25 mm as dropping offset by 25. The difference is stud engagement, because a spacer pushes the wheel off the hub while a lower-offset wheel still seats on it.

Wheel offset comparison: up to three wheels side by side →
Backspacing ↔ offset calculator →
Also check the bolt pattern →
Wheel Offset Explained →
Backspacing vs Offset →