Feet and Inches Calculator
Convert, add, and subtract feet and inches — including common fractions — and see total inches, decimal feet, centimetres, and metres instantly.
Reviewed October 7, 2026 Runs in your browser — inputs are never stored
Feet and Inches Calculator
Convert, add, subtract, and show total inches plus decimal feet. 1 ft = 12 in exactly.
Result
5 ft 8 in
68 total inches
Formula: total inches = (feet × 12) + inches. Decimal feet = feet + (inches ÷ 12). 1 in = 2.54 cm exactly.
| Feet and inches | Total inches | Decimal feet |
|---|---|---|
| 1 ft 0 in | 12 in | 1.00 ft |
| 2 ft 0 in | 24 in | 2.00 ft |
| 3 ft 6 in | 42 in | 3.50 ft |
| 4 ft 0 in | 48 in | 4.00 ft |
| 5 ft 0 in | 60 in | 5.00 ft |
| 5 ft 6 in | 66 in | 5.50 ft |
| 5 ft 8 in | 68 in | 5.6667 ft |
| 6 ft 0 in | 72 in | 6.00 ft |
| 6 ft 4 in | 76 in | 6.3333 ft |
| 6 ft 6 in | 78 in | 6.50 ft |
| 7 ft 0 in | 84 in | 7.00 ft |
| 8 ft 0 in | 96 in | 8.00 ft |
| 10 ft 0 in | 120 in | 10.00 ft |
This tool provides general unit conversions for everyday and educational use. For regulated, legal, or scientific applications, verify conversion factors against the applicable official standard.
About the Feet and Inches Calculator
The Feet and Inches Calculator on CalcWisee converts mixed imperial lengths using the exact factor 1 foot = 12 inches. Enter feet, whole inches, and a common fraction (1/2 through 1/16) to get total inches, decimal feet, centimetres, and metres. Reverse modes turn a total inch count or a decimal-foot value back into feet and inches. Add and subtract modes convert both measurements to inches first, then return a normalized feet-and-inches result so construction and height math stays consistent. Inputs accept decimals and scientific notation and reject empty, negative, and non-finite values.
How to use it
- 1Choose the mode: convert, inches to feet and inches, add or subtract.
- 2Enter feet, inches and an optional fraction for each measurement.
- 3Read the total in inches, decimal feet and metric units.
- 4Copy, share or print the result with the buttons below it.
Worked example
5 ft 8 in = 5 × 12 + 8 = 68 inches = 5.667 ft. Adding 5 ft 8 in and 3 ft 7 in gives 111 inches, or 9 ft 3 in.
How it works
The relationship
One international foot equals exactly 12 inches. Total inches = (feet × 12) + inches. Decimal feet = feet + (inches ÷ 12).
Worked examples
5 ft 8 in = (5 × 12) + 8 = 68 inches = 5.6667 decimal feet. 5 ft 8 in + 3 ft 7 in = 111 inches = 9 ft 3 in. 8 ft 6 in − 3 ft 9 in = 57 inches = 4 ft 9 in. 70 inches = 5 ft 10 in. 7.5 decimal feet = 7 ft 6 in.
Fractions
Construction sizes often use 1/2, 1/4, 1/8, and 1/16 inch. 5 ft 6 1/2 in = (5 × 12) + 6.5 = 66.5 inches.
Who it is for
Builders, carpenters, interior designers, architects, students, and anyone measuring height, lumber, rooms, or furniture in imperial units.
Why it helps
Mixed feet-and-inches arithmetic is easy to mis-carry, especially with fractions. Converting through total inches keeps addition, subtraction, and metric equivalents consistent.
Common use cases
- Adding board lengths in woodworking
- Converting height to inches or centimetres
- Working out room dimensions
Tips for better results
- Remember 1 foot = 12 inches exactly (international foot = 0.3048 m).
- Normalize inches of 12 or more — they carry into extra feet.
- Use 1/16-inch fractions for woodworking; enter the whole inches separately from the fraction.
- Decimal feet are not the same as feet-and-inches notation: 7.5 ft = 7 ft 6 in.
- For other units, continue in the Unit Converter or Length Converter.
Common mistakes to avoid
- Treating 5.5 feet as 5 ft 5 in instead of 5 ft 6 in.
- Forgetting to add the leftover inches after multiplying feet by 12.
- Subtracting the larger length from the smaller and reporting a negative length as a dimension.
- Mixing the US survey foot with the international foot on long survey distances.
- Rounding fractional inches before adding several cuts, which compounds error.
Frequently asked questions
A:There are exactly 12 inches in one international foot.
A:Multiply feet by 12 and add the remaining inches: total inches = (feet × 12) + inches. Example: 5 ft 8 in = 68 inches.
A:Divide by 12. The whole number is feet and the remainder is inches. 70 inches = 5 ft 10 in.
A:Convert each length to inches, add or subtract, then divide by 12 to return to feet and inches.
A:5.5 decimal feet is the same length as 5 ft 6 in, not 5 ft 5 in. Decimal feet = feet + (inches ÷ 12).
Reviewed for accuracy · Last updated October 7, 2026
Conversion factors are based on internationally defined SI units and standard metric/imperial equivalence tables.
CalcWisee Editorial Team
Calculator development and formula review
CalcWisee is an independent site founded by Ayman. Every calculator is built from a published formula or official definition, tested against hand-worked examples before it goes live, and corrected promptly when a reader reports an issue to ayman@calcwisee.com.
Expertise: Financial mathematics, Health and fitness formulas, Applied mathematics, Unit conversion standards
References & sources
Related guides
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