Feet & Inches Calculator

Feet & Inches Calculator

Use feet or inches or both, fractions or decimals

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Supports decimals (e.g. 10.5) and integers (e.g. 10).
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Supports fractions (e.g. 3/4) and mixed numbers (e.g. 61 3/4).
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Rounds the fractional inch result to this precision.

Calculating Feet and Inches

When framing a wall, cutting trim, or planning a room layout, measurements rarely come in perfect whole numbers. You usually end up dealing with a messy combination of whole feet, fractions on your tape measure, and decimal calculations from building plans.

We built this VersaCalculator tool to handle those mixed formats instantly. You can input decimals (like 10.5), standard fractions (like 3/4), or mixed numbers (like 61 3/4) directly into the fields, and the calculator will standardize the math behind the scenes.

How to Use the Calculator

  • Standard Arithmetic (Add & Subtract): Select your operator, enter your two lengths, and get the combined total. This is ideal for calculating total baseboard length or finding the difference between two wall measurements.
  • Finding Area (Multiply): If you select multiplication, the tool automatically knows you are looking for an area. It multiplies your two length inputs and outputs the result in square feet, square inches, and metric equivalents.
  • Scaling (Multiply/Divide by a Factor): If you are working from scaled blueprints or need to divide a piece of lumber into equal sections, use the “by a factor” option. This allows you to divide a measurement like 10 ft 5 in by a solid number, like 3.
  • Precision Rounding: Tape measures don’t use infinite decimals. By default, the calculator rounds your fractional inches to the nearest 1/8″, but you can adjust the dropdown to get as precise as 1/64″ or as broad as the nearest full inch.

How to Add, Subtract, Multiply, and Divide Lengths

If you are on a job site without your phone, calculating these measurements manually requires a specific process. You cannot simply add the feet together and the inches together without eventually converting them, because inches operate on a base-12 system, not base-10.

The foolproof method is to convert everything into total decimal inches, perform your math, and then convert the final number back into feet and fractional inches.

Step 1: Convert Everything to Inches Multiply your feet by 12 and add the remaining inches.

Total Inches = (Feet × 12) + Inches

Example for 5 ft 8 in:
Total Inches = (5 × 12) + 8
Total Inches = 60 + 8 = 68 inches

Step 2: Perform Your Calculation Once all your measurements are in inches, you can add, subtract, multiply, or divide them normally.

Adding 5' 8" and 3' 6"
Measurement A: (5 × 12) + 8 = 68 inches
Measurement B: (3 × 12) + 6 = 42 inches

68 + 42 = 110 Total Inches

Step 3: Convert Back to Feet and Inches To get your final readable measurement, divide your new total inches by 12 to find the feet. The remainder becomes your inches.

Feet = Floor(Total Inches ÷ 12)
Remaining Inches = Total Inches - (Feet × 12)

Example for 110 Total Inches:
Feet = Floor(110 ÷ 12) = 9 feet
Remaining Inches = 110 - (9 × 12) = 110 - 108 = 2 inches

Final Answer = 9 ft 2 in

Calculating Square Footage (Area)

When you multiply two linear measurements (length × width), the result is an area. This is how you determine how much flooring, drywall, or paint you need for a project.

If you multiply inches by inches, your result is in square inches. To convert square inches into square feet, you must divide by 144 (because 12 inches × 12 inches = 144).

Room Dimensions: 10 ft 6 in by 12 ft 0 in

Length in inches: (10 × 12) + 6 = 126 inches
Width in inches: (12 × 12) + 0 = 144 inches

Area = 126 × 144 = 18,144 Square Inches
Square Feet = 18,144 ÷ 144 = 126 Square Feet

Imperial to Metric Conversions

Construction and DIY projects frequently require jumping between imperial and metric systems, especially when ordering materials or interpreting modern hardware specifications.

Our calculator automatically outputs metric equivalents (centimeters and meters) alongside your imperial results. If you need to do this manually, use these standard conversion factors:

  • Inches to Centimeters: Multiply total inches by 2.54
  • Feet to Meters: Multiply total feet by 0.3048
  • Square Inches to Square Centimeters: Multiply by 6.4516
  • Square Feet to Square Meters: Multiply by 0.0929.

Sources: CalculatorSoup, Inch Calculator, Apple App Store (Feet and Inches Calculator App), Omni Calculator, Calculator Online, RapidTables, Scientific Calculator Online, The Calculator Site.