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Decimal & Fraction Converter

Two-way conversion between decimal inches/feet and feet-inches-fractions. Snaps to 1/16, 1/32, or 1/64 — whatever your tape measure reads.

Decimal → Fraction

Fractional reading
— mm

Feet + Inches + Fraction → Decimal

/
Decimal value
Decimal inches
Millimeters
Meters
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How fractions and decimal inches relate

A tape measure divides each inch into halves, then quarters, eighths, sixteenths, and (on machinist scales) thirty-seconds and sixty-fourths. To convert decimal inches to a fraction, multiply the decimal portion by the denominator you want, round to the nearest whole number, and simplify.

numerator = round(decimal × denominator) fraction = numerator / denominator (reduce to lowest terms)

Worked example: 0.4375" with a denominator of 16. 0.4375 × 16 = 7.00, so it lands on exactly 7/16". Another: 0.3" with a denominator of 32. 0.3 × 32 = 9.6, rounds to 10/32 → 5/16".

Decimal feet to feet-inches

Multiply the decimal portion of the feet value by 12, and that's your inches. 8.75 ft → 8 ft 9 in. 12.333 ft → 12 ft 4 in. Then take the decimal portion of the inches result and convert that to a fraction as above.

Decimal inch ↔ fraction reference chart

Decimal32nds16ths8thsmm
0.01561/320.40
0.03131/320.79
0.06252/321/161.59
0.09383/322.38
0.12504/322/161/83.18
0.15635/323.97
0.18756/323/164.76
0.21887/325.56
0.25008/324/162/8 = 1/46.35
0.312510/325/167.94
0.375012/326/163/89.53
0.437514/327/1611.11
0.500016/328/164/8 = 1/212.70
0.562518/329/1614.29
0.625020/3210/165/815.88
0.687522/3211/1617.46
0.750024/3212/166/8 = 3/419.05
0.812526/3213/1620.64
0.875028/3214/167/822.23
0.937530/3215/1623.81
1.000032/3216/168/8 = 125.40

Frequently asked questions

How do you convert decimal inches to a fraction?
Multiply the decimal portion by 16, 32, or 64, round to a whole number, and simplify. 0.625 × 16 = 10 → 10/16 = 5/8".
What is 0.625 inches as a fraction?
5/8 exactly. (5 ÷ 8 = 0.625.)
How do you convert decimal feet to feet and inches?
Whole number = feet. Multiply the decimal portion by 12 for inches. 8.75 ft = 8 ft 9 in.
Why aren't tape measures in tenths?
Customary units are built on halving. You can always eyeball halfway between marks — handy when you don't have a finer scale.
Smallest tape-measure fraction in common use?
1/16" on contractor tapes, 1/32" on machinist rules, 1/64" on precision scales and some engineering rules.

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