length guide
Convert Feet and Inches Without Treating Inches as Decimals
Translate mixed feet-and-inches notation into decimal feet, convert to centimeters, and handle a rounded inch value that carries into the next foot.
Published October 9, 2026 by SOLVEOZA Editorial
Quick answer
5 feet 6 inches is 5 + 6/12 = 5.5 feet, or 167.64 cm. The decimal number 5.6 feet is different: its fractional foot is 7.2 inches.
Decode the notation first
A record written as 5 ft 6 in contains two units. A form asking for decimal feet expects one number in feet. Do not copy the inches after a decimal point: feet contain 12 inches, so a tenth of a foot is 1.2 inches.
This guide uses positive dimensions in international feet and inches. Keep the source notation in your working notes. A bare 5.6 with no unit cannot tell you whether the writer intended a decimal measurement or an informal way of writing mixed units.
Use total inches as the intermediate value
Multiply whole feet by 12 and add the inches. For 5 ft 6 in, this gives 66 inches. Divide by 12 for decimal feet or multiply by 2.54 for centimeters. Both routes describe the same length.
| Source | Total inches | Decimal feet | Centimeters |
|---|---|---|---|
| 5 ft 6 in | 66 | 5.5 | 167.64 |
| 5.6 decimal ft | 67.2 | 5.6 | 170.688 |
| 6 ft 0 in | 72 | 6 | 182.88 |
| 0 ft 9 in | 9 | 0.75 | 22.86 |
Enter one unit at a time in the converter
Length Converter accepts a numeric value and a unit, not a string such as 5 ft 6 in. Enter 66 with source inches and destination centimeters to reproduce 167.64. Alternatively enter 5.5 feet with destination centimeters.
To check a result, convert it back using the unrounded value whenever available. Converting 170.688 cm back to feet gives 5.6. If you copied only 171 cm, a different reverse result is expected because the input was already rounded.
Carry rounded inches into the next foot
For decimal feet x, take the whole-number feet and multiply the remaining fraction by 12. A value of 5.999 feet gives 5 feet and 11.988 inches before rounding. To the nearest whole inch that becomes 6 ft 0 in, not 5 ft 12 in.
Round once at the required display precision. If you need an exact cut length, a measurement tolerance, or a historical survey unit, establish that requirement separately. More digits in a conversion cannot make the original measurement more accurate.
Make the result easy to reuse
Write a result as 167.64 cm rather than just 167.64. When keeping both formats, use separate labeled columns for original notation, total inches, and converted length. This makes a later change of display precision possible without reinterpreting the source.
Before submitting to a form, check whether it has separate feet and inches boxes or a single decimal field. A mathematically correct number entered into the wrong field format is still the wrong submission.
Methodology
- Cross-check total inches and decimal feet routes.
- Test carry at 11.988 inches independently of display formatting.
Limitations
- No survey-unit or construction-tolerance advice.
- Conversion precision is not measurement accuracy.
- Ambiguous mixed notation must be clarified before conversion.
Sources
Unit relationships checked against NIST; mixed-notation examples are original calculations using the tool's international-unit factors.
- SI conversion factors (accessed 2026-10-09)
FAQ
Is 5.6 feet the same as 5 feet 6 inches?
No. It is 5 feet 7.2 inches.
What if rounding produces 12 inches?
Carry those 12 inches into one additional foot and display zero inches.
Can I enter mixed notation in Length Converter?
No. First convert to a single numeric value such as total inches or decimal feet.
Does converting back recover a rounded source?
Not necessarily. Once digits are discarded, converting units cannot restore them.