Feet and Inches to Decimal Calculator
Feet and inches to convert
Enter feet and inches — inches can be a decimal or a fraction, such as 9 or 5 3/8.
Decimal feet
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Enter feet and inches to convert.
- Total decimal inches
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- Millimetres
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To convert feet and inches to decimal feet, divide the inches by 12 and add that to the whole number of feet. 5' 9" has 9 ÷ 12 = 0.75, so 5' 9" = 5.75 decimal feet.
From a Tape Measure to a Drawing
A tape measure gives you feet and inches; a survey plan, CAD file or spreadsheet wants a single decimal number.
This is the reverse of the decimal feet to inches calculator: instead of splitting a decimal foot value into feet and inches, here you start with feet and inches and collapse them into one decimal figure — the format that survey software, area calculations and legal property descriptions all expect.
The Feet and Inches to Decimal Formula
One formula collapses feet and inches into a single decimal-feet value.
DF, decimal feet, equals the whole feet plus the inches divided by 12.
- FTThe whole number of feet, such as 5 in 5' 9".
- INThe inches, such as 9 in 5' 9" — can itself be a decimal or fraction.
- DFThe result: FT + (IN ÷ 12).
Worked calculation — 5' 9"
- 9 ÷ 12 = 0.75Convert the inches to a fraction of a foot
- 5 + 0.75 = 5.75Add the whole feet
5' 9" = 5.75 decimal feet
Feet and Inches as Decimal Feet
Common site measurements converted to their decimal-feet equivalent.
| Feet & inches | Decimal feet |
|---|---|
| 5' 0" | 5 ft |
| 5' 6" | 5.5 ft |
| 8' 3" | 8.25 ft |
| 10' 9" | 10.75 ft |
| 12' 6" | 12.5 ft |
| 15' 4" | 15.3333 ft |
| 20' 8" | 20.6667 ft |
Converting Without a Calculator
- Divide the inches by 12. 4" ÷ 12 = 0.3333.
- Add the result to the whole feet. 7' 4" → 7 + 0.3333 = 7.3333 ft.
- Round to the precision your drawing or spreadsheet needs — usually two to four decimal places.
Frequently Asked Questions
How do you convert feet and inches to decimal feet?
Divide the inches by 12, then add that to the whole number of feet. For 5' 9": 9 ÷ 12 = 0.75, and 5 + 0.75 = 5.75 decimal feet.
What is 5' 9" in decimal feet?
5' 9" equals 5.75 decimal feet. The 9 inches becomes 0.75 of a foot (9 ÷ 12 = 0.75), added to the 5 whole feet.
How do surveyors record feet and inches as decimal feet?
They convert the inches portion of a field measurement to a decimal by dividing by 12, then add it to the feet, so the whole distance can be entered as a single decimal number on a drawing or in a CAD system — 8' 3" becomes 8.25 ft.
What is 12' 6" as decimal feet?
12' 6" equals 12.5 decimal feet, since 6 ÷ 12 = 0.5.
Can inches include a fraction when converting to decimal feet?
Yes. Convert the fractional inches to a decimal first — 5 3/8" = 5.375" — then divide by 12 as usual. For 5' 5 3/8": 5.375 ÷ 12 ≈ 0.4479, so the total is about 5.4479 decimal feet.
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