offset / ET calculator

Automotive Calculator

Wheel Offset / ET Calculator

Compare wheel width and offset changes instantly.

Current Wheel

in
mm

New Wheel

in
mm
Outer Position +17.7mm The new wheel sits further out.
Inner Clearance -7.7mm The new wheel is closer to the suspension.
Width Change +25.4mm Wheel width difference.
Compared with your current wheel, the new wheel sits 17.7mm further out and has 7.7mm less inner clearance.
Note: This calculator compares wheel position only. Always check tyre width, suspension clearance, brake clearance, arch clearance and manufacturer fitment guidance before fitting wheels.

Wheel Offset / ET Calculator

Need to compare wheel offset changes quickly and accurately? Our free Wheel Offset / ET Calculator shows how a new wheel width and offset will affect outer position and inner clearance.

Whether you are comparing:

  • current wheels against new wheels
  • different ET values
  • wider wheel fitments
  • stance changes
  • arch clearance
  • suspension clearance
  • track width changes

…our calculator makes it simple.

What Is Wheel Offset / ET?

Wheel offset, often shown as ET, is the distance between the wheel’s mounting face and the centreline of the wheel. Offset affects how far a wheel sits in or out from the hub and is commonly used across:

  • automotive fitment
  • alloy wheel upgrades
  • stance and track width changes
  • arch clearance checks
  • suspension clearance checks
  • brake clearance planning

What Does ET Mean?

ET comes from the German word “Einpresstiefe”, meaning insertion depth. In wheel fitment, ET is normally measured in millimetres and helps define whether a wheel sits further in or further out.

  • Higher ET usually moves the wheel further in
  • Lower ET usually moves the wheel further out
  • Wheel width also affects inner and outer position
  • Tyre width can change real-world clearance
  • Spacers effectively reduce offset

Wheel Offset Formula

To compare wheel position:

Outer Change = New Outer Position - Current Outer Position

Inner Clearance Change = Current Inner Position - New Inner Position

Example:

A wider wheel with lower ET will usually sit further out and may reduce inner suspension clearance.

Common Wheel Offset / ET Checks

Current Wheel New Wheel Result
8J ET45 9J ET40 Sits further out
8.5J ET50 10J ET45 Wider with reduced inner clearance
9J ET55 9J ET45 Same width, sits further out
10J ET40 9J ET50 Narrower and sits further in
8J ET35 8J ET45 Same width, sits further in
9J ET45 9.5J ET45 Wider both inside and outside
9J ET50 9J ET40 10mm further out
8.5J ET45 8.5J ET35 10mm further out

Why Use Our Wheel Offset / ET Calculator?

  • Instant live calculation
  • Compare current and new wheels
  • Shows outer position change
  • Shows inner clearance change
  • Mobile friendly
  • Simple dark-mode design
  • Popular Wheel Offset / ET Searches

People often search for:

  • wheel offset calculator
  • ET calculator
  • alloy wheel offset calculator
  • wheel fitment calculator
  • will my wheels fit
  • offset difference calculator
  • wheel poke calculator

Our calculator is designed to answer these instantly.

Automotive & Fitment Uses

Wheel offset calculations are commonly used for:

  • alloy wheel upgrades
  • stance planning
  • Porsche wheel fitment checks
  • track car setups
  • suspension clearance checks
  • brake clearance checks
  • arch clearance checks
  • Tyre & Wheel Uses

This calculator is also useful for:

  • checking wider wheels
  • comparing OEM and aftermarket wheels
  • understanding spacer effects
  • planning track width changes
  • avoiding rubbing issues
  • understanding wheel poke

Use WhatsThisIn.com to compare wheel offset and fitment changes instantly with precision.