Feet and Inches Calculator
Our free length & area converter handles feetand inches conversions. See tables, ratios, and examples for quick reference.
Reviewed for accuracy by Manoj Kumar, Mathematics Educator
Feet and Inches Calculator
Calculator
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Formula: Total Inches = (Feet x 12) + Inches
Worked example — 9 feet 2 inches (110 inches total | 279.40 cm)
Formula
Total Inches = (Feet x 12) + Inches
Convert each measurement to inches, perform the operation, then convert back. One foot equals 12 inches. One inch equals 2.54 centimeters.
Worked Examples
Example 1: Adding Two Measurements
Problem:Add 5 feet 8 inches to 3 feet 6 inches.
Solution:Convert to total inches: 5 ft 8 in = (5 x 12) + 8 = 68 inches 3 ft 6 in = (3 x 12) + 6 = 42 inches Sum = 68 + 42 = 110 inches Convert back: 110 / 12 = 9 feet, remainder 2 inches Result = 9 feet 2 inches = 279.40 cm
Result:9 feet 2 inches (110 inches total | 279.40 cm)
Example 2: Subtracting Measurements
Problem:Subtract 2 feet 9 inches from 8 feet 3 inches.
Solution:Convert to total inches: 8 ft 3 in = (8 x 12) + 3 = 99 inches 2 ft 9 in = (2 x 12) + 9 = 33 inches Difference = 99 - 33 = 66 inches Convert back: 66 / 12 = 5 feet, remainder 6 inches Result = 5 feet 6 inches = 167.64 cm
Result:5 feet 6 inches (66 inches total | 167.64 cm)
Frequently Asked Questions
How do I add feet and inches together?
To add feet and inches, first convert both measurements entirely to inches by multiplying the feet value by 12 and adding the remaining inches. Then add the two totals together. Finally, convert the result back to feet and inches by dividing by 12, where the quotient is feet and the remainder is inches. For example, to add 5 feet 8 inches and 3 feet 6 inches: convert to 68 inches and 42 inches, add to get 110 inches, then divide 110 by 12 to get 9 feet 2 inches. This method ensures accuracy and avoids errors from carrying over inches greater than 12.
How do I convert feet and inches to centimeters?
To convert feet and inches to centimeters, first convert the entire measurement to inches by multiplying feet by 12 and adding the inches portion. Then multiply the total inches by 2.54, since one inch equals exactly 2.54 centimeters. For example, 5 feet 10 inches equals 70 inches total, which converts to 70 x 2.54 = 177.8 centimeters. This conversion is essential when working with international building materials, medical height measurements, or scientific applications that use the metric system rather than imperial units commonly used in the United States.
What is the difference between feet-inches and decimal feet?
Feet-inches notation expresses measurements as whole feet plus remaining inches, such as 5 feet 6 inches. Decimal feet express the same measurement as a single decimal number, such as 5.5 feet, where the decimal portion represents a fraction of a foot rather than inches. To convert feet-inches to decimal feet, divide the inches by 12 and add to the feet: 5 feet 6 inches becomes 5 + 6/12 = 5.5 feet. Conversely, 5.75 decimal feet equals 5 feet 9 inches. Decimal feet are commonly used in surveying and engineering calculations, while feet-inches are standard in construction and everyday measurements.
Can I subtract a larger measurement from a smaller one?
Yes, you can subtract a larger measurement from a smaller one, and the result will be a negative value indicating the difference in the opposite direction. Feet and Inches Calculator handles negative results by showing the magnitude with a negative sign. For example, subtracting 6 feet 3 inches from 4 feet 10 inches yields negative 1 foot 5 inches, meaning the second measurement exceeds the first by that amount. Negative results commonly arise in construction when calculating clearances, offsets, or differences between planned and actual dimensions.
How accurate are fractional inch approximations?
Fractional inch approximations in construction typically use increments of 1/8 inch, 1/16 inch, or 1/32 inch. An eighth-inch fraction provides accuracy to plus or minus 0.0625 inches (1.5875 mm), which is sufficient for most framing and general carpentry work. Sixteenth-inch fractions achieve plus or minus 0.03125 inches (0.794 mm) precision, suitable for cabinetry and finish carpentry. For precision machining or engineering, decimal inches or metric measurements are preferred. Feet and Inches Calculator rounds to the nearest 1/8 inch for the fractional display while also providing the exact decimal value for more precise applications.
References
Reviewed for accuracy by Manoj Kumar, Mathematics Educator · Editorial policy
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