Craft Quantities
Plan & Takeoffs

Measurements & Conversions

Inches to Centimetres Calculator

Convert inches to centimetres for metric suppliers, spec sheets and shipping dimensions.

  • Answers as you type
  • Every formula cited
  • Calculated in your browser
SettingsSettings for this calculationUS
Market
Imperial · sales tax
The measurement in inches.

Enter fractions as decimals — a quarter is 0.25, a half 0.5, three-quarters 0.75. If the figure is in feet and inches, multiply the feet by twelve first: 6 ft 2 in is 74 in.

Length

91.44 cm

High confidence

1 inch = 2.54 cm exactly, by international agreement since 1959. Exact by definition, but a converted nominal size is still a nominal size — check the actual dimension.

Same length in millimetres
914.4 mm
Same length in metres
0.91 m
Then change the inputs to see how far the answer moves.

Show calculation logic

How this was calculated

Formula source(s)

  • International yard and pound agreement (1959): 1 inch = 25.4 mm = 2.54 cm exactly

Inputs used

Length (in)
36

Intermediate steps

Same length in millimetres
914.4 mm
Same length in metres
0.91 m
Final result91.44 cm

Confidence note: 1 inch = 2.54 cm exactly, by international agreement since 1959. Exact by definition, but a converted nominal size is still a nominal size — check the actual dimension.

Add the equipment this sizes

This result is a specification — 91.44 cm — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.

Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.

Sources checked 2026-09-11 · v1.0.0

Regulatory standards & verification citations1
  1. International yard and pound agreement (1959): 1 inch = 25.4 mm = 2.54 cm exactly
Cite this page

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

This is the conversion that happens when an imperial-sized thing has to be described to someone who works in metric: a shipping crate for a European courier, a countertop cut-out for a fabricator who quotes in millimetres, a piece of US plywood being fitted into a metric stud bay. The arithmetic is exact and trivial; the failure is always the same and has nothing to do with arithmetic. Imperial construction sizes are nominal — a name, not a measurement — and converting the name produces a number that describes nothing you can buy. Measure the object, convert the measurement, and specify the product by the designation its own market uses.

How to calculate inches to centimetres in 2 steps

  1. Length (in)The measurement in inches.
  2. LengthThe tool computes the length from those figures and shows the formula, its sources, and a confidence rating alongside it.

Inches to Centimetres at common values

Page defaults, not your figures above.

Length (in)Length (cm)
512.7
1025.4
2050.8
50127
100254
200508

Frequently asked questions

Should I give a supplier centimetres or millimetres?
Millimetres, unless they asked for something else. Metric fabrication, joinery and steelwork all work in whole millimetres with no unit mark on the drawing, and a centimetre figure invites someone to wonder whether 12.5 means 125 mm or 1250. Centimetres are a shopper's unit and a body-measurement unit; they are not a workshop unit.
Does converting a nominal size give the real size?
No, and this is the trap. A US 2×4 is 1.5 by 3.5 in actual, which is 3.81 by 8.89 cm — and the European equivalent is not that, it is a 38 × 89 mm sawn or a 45 × 95 planed section depending on the standard it is cut to. Convert measured dimensions. Never convert a nominal name and expect a product to match it.
Why do US and European appliance openings not line up?
Because the modules were set independently. European kitchens are built on a 600 mm module; the US standard base cabinet and freestanding range are 30 in, which is 762 mm. The difference is 162 mm, far more than any adjustment gap, so the two are not interchangeable regardless of what the conversion says.
How many decimal places should I keep?
Enough to preserve the tolerance of the original, and no more. An inch figure given to the nearest sixteenth carries about 1.6 mm of resolution, so one decimal place of centimetres is already at the limit of what the source knew. Rounding to the nearest half-centimetre is honest for a site dimension and dangerous for a machined part.
Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — a confirmed fix gets a permanent check of its own, so the same mistake cannot come back.