Length Converter

Convert mm, inches, and feet for offset, bore, stroke, and overall diameter.

Bore, stroke, offset, tire diameter

Formula

divide the length value by 25.4

Full length board

Same input, every length unit — tap a tile to set the right-hand unit.

Millimeters to inches for shop measurements

  • 1 inch = 25.4 mm exactly. ET 35 is 1.38 in; a 3.48 in SBC stroke is 88.4 mm.
  • Offset, backspacing, bore, and stroke all show up in mixed catalogs.
  • Converting ET to inches does not tell you whether the wheel clears the fender.

Length is the unit you hit first on a wheel or engine parts page: ET in millimeters, backspacing in inches, bore in inches, piston compression height in millimeters. This converter keeps the constant honest — 25.4 mm per inch — and shows mm, cm, m, inches, and feet on one board.

Wheel offset is still a length. Convert ET 35 to 1.38 in if your calipers read inches, then check poke and backspacing on the wheel offset calculator. A tire’s 265 mm section width is not a fitment verdict either; that belongs on the tire size calculator.

For bore and stroke, convert the published number, then use the engine displacement calculator if you need liters or cubic inches from the set.

Common length conversions

Offsets, strokes, and a couple of tape-measure checks.

Millimeters and inches
JobYou haveYou need
Wheel offset ET 3535 mm1.38 in
ET 4545 mm1.77 in
SBC 350 stroke3.48 in88.4 mm
LS 4.000 in bore4.000 in101.6 mm
1 inch1 in25.4 mm
1 in = 25.4 mm exactly. 1 ft = 12 in = 304.8 mm.

When this is the wrong tool

Wheel fitment needs offset, width, and backspacing together — use the wheel offset calculator. Tire diameter from a size code is the tire size calculator. Bolt circles are a pattern, not a single length.

How to convert mm to inches

  1. Enter the measured or catalog length. Offset, stroke, or a caliper reading.
  2. Set mm or inches. Match the side of the catalog you are reading.
  3. Read the other system. Tap a board tile if you want feet or centimeters on the right card.

Length converter FAQ

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