Feet, inches and centimeters
Keep compound feet separate from decimal feet
Five feet eight inches is 5 ft + 8 in, not 5.8 ft. The first measurement equals 172.72 cm; the decimal value equals 176.784 cm. A dot separates a whole number from a fraction of a foot, not feet from inches. Select the input format that matches your measurement before entering its numbers in the converter above.
This tool changes a known length between units. It does not measure a room, determine how accurately a part was made or decide whether a dimension meets an installation requirement. Keep the original number, unit and measurement purpose together when recording a result.
Choose a format before entering numbers
| What your note contains | Input format | How to enter it |
|---|---|---|
| 5 feet and 8 inches | ft + in | Whole feet 5, remaining inches 8 |
| 5.8 feet as a decimal | Decimal feet | Enter 5.8 in the single value field |
| 68 inches | Inches | Enter 68; standalone inches may exceed 12 |
| 172.72 centimeters | Centimeters | Enter 172.72 for metric-to-US results |
| 7 3/8 inches | Inches, Whole + fraction | Whole inches 7, numerator 3, denominator 8 |
Compound feet must be whole numbers. The remaining inches must be at least zero and below 12, because 12 inches belongs in the next whole foot. A note of 4 ft + 12 in should therefore become 5 ft + 0 in, or 60 standalone inches. Enter zero explicitly in a required field when there is no remainder; an empty field is not zero.
Follow the conversion through
The NIST international-foot definition gives 1 ft = 0.3048 m exactly. NIST Appendix B.8 gives 1 in = 2.54 cm. These definitions yield 12 in per foot. For compound input:
total inches = whole feet × 12 + remaining inches
centimeters = total inches × 2.54
| Starting value | Total inches | Centimeters |
|---|---|---|
| 5 ft + 8 in | 68 | 172.72 |
| Decimal 5.8 ft | 69.6 | 176.784 |
| 0 whole in + 1/2 in | 0.5 | 1.27 |
| 2 ft + 7 3/8 in | 31.375 | 79.6925 |
For the last row, enter compound feet 2 and select Whole + fraction for inches. Enter whole inches 7, numerator 3 and denominator 8. The inch remainder is 7 + 3/8 = 7.375, and 24 + 7.375 = 31.375 total inches. These are authored calculations, not observations of a real object.
The tool accepts fraction denominators 2, 4, 8, 16, 32 or 64. The numerator must be a whole number below its denominator. For 9/8 in, normalize to whole inches 1 plus 1/8. Do not type 7 3/8 into a decimal field, or enter a slash expression as the numerator. Fraction inputs are provided through separate fields; reverse results do not offer a fraction or selectable denominator.
Read the metric-to-compound result
For 200 cm, divide by 2.54 to obtain approximately 78.74015748 total inches. Six complete groups of 12 inches account for 72 inches, leaving approximately 6.74015748 inches. The compound display is 6 ft + 6.7402 in.
The remaining inches round to four decimals using half-up rounding. If that rounded remainder becomes 12.0000, the display carries one into the feet and shows a zero remainder. For example, 30.479999 cm is slightly below one foot, but rounds to 1 ft + 0.0000 in. This is a display rule, not extra length added to the measurement.
The separate decimal feet, total inches and centimeter rows provide their own four-place results and expanded approximate digits up to twelve places. A compound row is a whole-unit-and-remainder presentation; it is not a promise of additional fractional output. Avoid re-entering a rounded display repeatedly when checking a conversion.
Use one length unit for a measurement workflow
If a rectangular space has one dimension written as 10 ft and the other as 120 in, convert both to the same linear unit before multiplying. Since 120 in equals 10 ft, the area is 10 × 10 = 100 ft². Multiplying the bare numbers 10 × 120 and calling the answer square feet would mislabel the result.
After measuring an area, use the area converter for ft²/m². For a rectangular box, the box-volume tool needs all three sides in one unit. If planning separate finished trim pieces, continue to the trim cut planner; a length conversion alone cannot supply a cutting layout or account for saw kerf. Measurements are not transferred automatically.
Check the accepted range and measurement limits
Single decimal fields accept nonnegative values through 1,000,000 with at most six decimal places. Whole-feet and whole-inch fraction fields accept whole numbers; the compound inch remainder must stay below 12. Negative values, comma-separated numbers, exponent notation, free-form calculations and malformed decimals such as 5..8 are rejected. Use a decimal point and omit unit letters from the numeric field.
The direction-switch button changes format and clears the input. Save your original measurement before switching and enter the new value explicitly. More output digits cannot improve an approximate tape reading. Zero is a valid known length, while an unknown dimension still needs measuring.
These conversions use the international foot only, not historical U.S. survey-foot records. They do not certify drawing suitability, installation tolerances or a medical interpretation of height. The two linked NIST sources were checked October 3, 2026 for the narrow length definitions; examples and input guidance are authored arithmetic and current tool instructions.
AI-assisted content. Examples are hypothetical and do not certify a measured object’s dimensions.