ToolwickFeet and Inches to Decimal Feet Calculator
Use this free feet and inches to decimal feet calculator to turn a measurement like 5 ft 6 3/8 in into decimal feet (5.5313 ft). It is built for surveyors, builders, estimators and anyone who needs tape-measure numbers in a spreadsheet-friendly form.
Estimates only. By using this calculator you agree to our Terms.
This tool converts units only. Always confirm critical dimensions on site before cutting or ordering material. Results are not engineering, permit or inspection approval.
How to Use This Feet and Inches to Decimal Feet Calculator
Type the whole feet into the first box, then the whole or decimal inches into the second. If your tape reads a fraction such as 3/8, pick it from the fraction menu, which covers every sixteenth of an inch. Press the button or hit Enter in any field. You get decimal feet as the headline number, with a table of total inches, normalized feet and inches, meters, millimeters and the rounding difference. Inches of 12 or more are fine; they are carried into feet. Use the checkbox for negative values such as an elevation below a benchmark.
Why This Matters
Tape measures speak feet, inches and fractions, but most software does not. Spreadsheets, CAD packages, surveying instruments and estimating tools all expect decimal feet. Type 5'6" into a cell and you get text, not a number. Converting by hand invites mistakes, and the classic one is treating 5 ft 6 in as 5.6 ft when it is really 5.5 ft.
The conversion comes up constantly. A concrete finisher turns a 14 ft 9 in slab length into 14.75 ft to multiply by width and depth. An excavation crew reads grade rods in tenths of a foot while the plans give feet and inches. A fence installer pricing 96 ft 4 in of run and a flooring estimator with an 11 ft 10 1/2 in room both need decimal feet before area or cost formulas work.
Small errors compound. Rounding 0.5313 ft to 0.5 ft loses about 3/8 in on one cut, and across 40 repeated studs or pickets that drift becomes visible.
How It's Calculated
One foot is exactly 12 inches, so inches become a fraction of a foot by dividing by 12. The calculator adds your fraction of an inch (sixteenths divided by 16) to your inches first, then converts:
Decimal feet = feet + (inches + fraction) ÷ 12
For a negative measurement the whole result is multiplied by −1, so −5 ft 6 in becomes −5.5 ft rather than −4.5 ft. Total inches is feet × 12 + inches + fraction. Metric values use the exact international definition of 1 inch = 25.4 mm. That differs very slightly from the older U.S. survey foot, which appears only in some legacy land-survey data, so check your project's datum for boundary work.
Displayed results are rounded to the number of decimal places you choose. The table also shows the unrounded value and the rounding difference in inches, so you can see how much the display rounding could matter. If a result feeds a material order, round the quantity up, never down.
Quick Reference: Inches to Decimal Feet
| Inches | Decimal feet | Inches | Decimal feet |
|---|---|---|---|
| 1 in | 0.0833 | 7 in | 0.5833 |
| 2 in | 0.1667 | 8 in | 0.6667 |
| 3 in | 0.2500 | 9 in | 0.7500 |
| 4 in | 0.3333 | 10 in | 0.8333 |
| 5 in | 0.4167 | 11 in | 0.9167 |
| 6 in | 0.5000 | 1/2 in | 0.0417 |
| 1/4 in | 0.0208 | 1/8 in | 0.0104 |
Worked Example
Say a room measures 12 ft 7 3/8 in along one wall and you want decimal feet.
- Step 1: Convert 3/8 to decimal inches: 3 ÷ 8 = 0.375, so inches become 7.375.
- Step 2: Divide by 12: 7.375 ÷ 12 = 0.614583 ft.
- Step 3: Add the feet: 12 + 0.614583 = 12.614583 ft.
- Step 4: Round to 4 places: 12.6146 ft. The rounding difference is about 0.0002 in, which is negligible.
Total inches is 12 × 12 + 7.375 = 151.375 in, which is about 3.8449 m or 3,844.93 mm. Enter 12, 7 and 3/8 in the calculator above to see the same figures.
Tips & Common Mistakes
- Do not write inches as the decimal part. 5 ft 6 in is 5.5 ft, not 5.6 ft. The digits after the decimal point are fractions of a foot, not inches.
- Keep extra decimal places while calculating. Round only the final answer. Three places steps in about 1/80 in with a worst-case rounding error near 1/160 in; two places can be off by up to about 1/16 in.
- Round material quantities up. When the decimal feet feed a purchase, such as lumber, trim or pipe, round up and add waste so you never come up short.
- Check the unit on grade rods and survey plans. Some are already in tenths of a foot, which is not the same as inches ÷ 12. Do not convert twice.
- Measure twice, convert once. A misread fraction matters more than any rounding. Confirm key dimensions on site and follow your project documents and local requirements.
Frequently Asked Questions
How do I convert feet and inches to decimal feet?
Divide the inches by 12 and add the result to the whole feet. For example, 8 ft 3 in is 8 + 3 ÷ 12 = 8.25 ft. Include any fraction of an inch in the inches before dividing.
What is 6 inches in decimal feet?
Six inches is exactly 0.5 ft because 6 ÷ 12 = 0.5. So 10 ft 6 in equals 10.5 ft. Likewise 3 inches is 0.25 ft and 9 inches is 0.75 ft.
Is 5.6 feet the same as 5 feet 6 inches?
No. 5.6 ft is 5 ft plus 0.6 × 12 = 7.2 in, so it equals about 5 ft 7 3/16 in. Five feet six inches is 5.5 ft. Mixing these up is the most common conversion mistake.
How do I add fractions like 3/8 inch?
Choose the fraction in the dropdown and the calculator adds it to your inches. By hand, divide the top number by the bottom (3 ÷ 8 = 0.375), add it to the inches, then divide by 12.
How many decimal places should I use?
Four decimal places (0.0001 ft, about 1/800 in) suit most construction and estimating work. Two places is fine for rough takeoffs but can be off by up to about 1/16 in. Use more places for long runs or repeated multiplication.
Can I convert decimal feet back to feet and inches?
Yes. Multiply the decimal part by 12 to get inches. For 12.6146 ft, 0.6146 × 12 = 7.375 in, which is 7 3/8 in, so the answer is 12 ft 7 3/8 in.
Related Tools
Once your lengths are in decimal feet, they plug straight into area, material and wire-run calculations. These tools pair well with this converter: