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Feet and Inches to Decimal Feet Converter

Twelve feet six and three quarter inches is 12.5625 decimal feet. This converter goes both ways: type a tape reading and get decimal feet, decimal inches and metric, or type a decimal from a drawing and get the reading to find on your tape, rounded to the fraction you actually work to.

ft
in
Fractions are accepted exactly as you would read them off the tape — 6 3/4, 3 1/2, 15/16. A decimal works too.

Results are estimates for planning purposes. Verify with your supplier, engineer, or a qualified professional before ordering material or performing work.

Inches to decimal feet

The whole conversion is one division by twelve, but the table is faster than the arithmetic when you are reading a column of dimensions. Add the fraction line to the inch line: 6 3/4 in is 0.5000 + 0.0625 = 0.5625 ft.

InchesDecimal feetFraction of an inchDecimal feet
10.08331/160.0052
20.16671/80.0104
30.25003/160.0156
40.33331/40.0208
50.41675/160.0260
60.50003/80.0313
70.58337/160.0365
80.66671/20.0417
90.75005/80.0521
100.83333/40.0625
110.91677/80.0729
121.000015/160.0781

Only 3, 6, 9 and 12 inches land on clean decimals. Everything else repeats, which is why a takeoff done in decimal feet and rounded at every line drifts, and one done in total inches does not.

Tenths of a foot — where the inch-long mistakes come from

Civil, survey and earthwork drawings are dimensioned in decimal feet, and a survey rod is graduated in tenths and hundredths. Architectural and structural drawings are dimensioned in feet and inches, because the people building from them are holding tapes graduated in sixteenths. Both are feet. They do not read the same way, and 0.5 ft is six inches, not five.

Tenths of a footInchesNearest 1/16 on the tape
0.11.21-3/16
0.22.42-3/8
0.33.63-5/8
0.44.84-13/16
0.56.06
0.67.27-3/16
0.78.48-3/8
0.89.69-5/8
0.910.810-13/16
0.010.12about 1/8

A hundredth of a foot is roughly an eighth of an inch, which is a handy field equivalence for grade stakes. Note that no tenth of a foot except a half lands on a clean sixteenth — the two systems do not share divisors, and that is the whole problem.

Why 0.3048 is exact, and why there used to be two feet

The foot is defined as 0.3048 meters, not measured to be. The 1959 international yard and pound agreement fixed the yard at exactly 0.9144 m, which makes the foot exactly 0.3048 m and the inch exactly 25.4 mm. There is no uncertainty attached to any of those numbers, and there is no rounding in the metric line of the results above.

What 1959 did not settle was geodetic surveying, which kept the older U.S. survey foot of exactly 1200/3937 m as a standing exception. The United States therefore carried two feet, two parts per million apart, for another sixty-three years. NIST and the National Geodetic Survey deprecated the survey foot on December 31, 2022; since January 1, 2023 the plain international foot applies everywhere except historic and legacy work.

Two parts per million is nothing on a tape and nothing on a building. It is several feet on a state plane coordinate in the millions, and that mismatch — the same northing meaning two different places depending on which foot was assumed — is what finally ended the exception. If you are working from a pre-2023 legal description or coordinate file, check which foot it was computed in. If you are laying out a wall, do not think about it again.

How it's calculated

Feet and inches to decimal feet
decimal feet = feet + inches / 12
The fraction is added to the inches first: 6 3/4 in is 6.75 in, and 6.75 / 12 is 0.5625 ft.
Decimal feet back to a tape reading
total inches = decimal feet × 12 → feet = floor(total / 12), inches = remainder, fraction = round(remainder × denominator) / denominator
The remainder is rounded to the fraction you chose, then reduced — 12/16 is shown as 3/4, not as 12/16.
The exact metric factors
1 in = 2.54 cm · 1 ft = 0.3048 m · 1 yd = 0.9144 m
All three are exact by definition, fixed by the 1959 international yard and pound agreement. They are not measured values and they do not carry an uncertainty.
Decimal feet are not tenths of an inch
0.5 ft = 6 in 0.1 ft = 1.2 in 0.05 ft = 0.6 in
A tenth of a foot is 1.2 inches. Reading a survey elevation of 0.5 ft as five inches is the single most common error this converter exists to prevent, and it is a full inch out.

Frequently asked questions

Divide the inches by 12 and add them to the feet. So 12 ft 6 3/4 in becomes 6.75 / 12 = 0.5625, plus 12, which is 12.5625 decimal feet. Add any fraction to the inches before dividing, not after.

Six inches, not five. Decimal feet are tenths and hundredths of a foot, so half a foot is half of twelve inches. The same trap catches 0.25 ft, which is three inches, and 0.75 ft, which is nine. If a number in a drawing has a decimal point and a foot mark, it is not inches.

1.2 inches, near enough to 1 3/16 on a tape. Surveyors and civil engineers work in tenths and hundredths of a foot because the arithmetic of cut and fill is easier without a base-twelve conversion in the middle of it. A hundredth of a foot is 0.12 in, roughly 1/8.

Because they are read by different people doing different arithmetic. Grades, elevations, stationing and earthwork volumes involve adding and subtracting long columns of numbers, and decimal feet make that possible without converting twelfths at every step — which is also why a survey rod is graduated in tenths and hundredths. Architectural and structural dimensions are built by people holding tapes graduated in sixteenths, so they are written the way the tape reads.

Multiply by 12 to get total inches, take the whole feet off, then round the leftover inches to the fraction you work to and reduce it. 12.5625 ft is 150.75 in, which is 12 ft and 6.75 in, which is 6 3/4 on the tape. The converter above does the rounding to a half, quarter, eighth, sixteenth, thirty-second or sixty-fourth.

Yes, exactly, and it has been since the international yard and pound agreement of 1959. The definition is not a measurement, so it carries no uncertainty: the yard is exactly 0.9144 m, the foot exactly 0.3048 m and the inch exactly 2.54 cm. Everything on this page follows from those three numbers.

It was a second, slightly longer foot — exactly 1200/3937 m — kept alive after 1959 as an exception for geodetic surveying. NIST and the National Geodetic Survey deprecated it on December 31, 2022, so since January 1, 2023 the plain international foot applies to everything except historic and legacy work. The two feet differ by 2 parts per million, which is invisible on a tape measure and worth several feet on a state plane coordinate in the millions.

Whatever your tape reads and your work justifies. A standard tape is graduated in sixteenths, and rounding a calculated dimension to a thirty-second that nobody can find on the tape is false precision. Machining and layout work in thousandths of an inch instead, which is why the decimal inch line in the results is there.

Sources & references

Content checked against these sources — last reviewed August 30, 2026.

By — Editorial team of SteelToeTools.com (published by LSEA SAS) Updated v1