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Feet & Inches Calculator: Free Online Length Converter

Use this free Feet and Inches Calculator to add, subtract, or convert lengths instantly. Supports fractions, decimals, imperial units, and metric conversions.

Calculate Feet & Inches
Quick Conversion Reference

Feet ⇄ Inches

1 ft12 in
2 ft24 in
3 ft36 in
4 ft48 in
5 ft60 in
6 ft72 in
7 ft84 in
8 ft96 in
9 ft108 in
10 ft120 in

Common Fractions

1/8"0.125"
1/4"0.25"
3/8"0.375"
1/2"0.5"
5/8"0.625"
3/4"0.75"
7/8"0.875"
1"1.0"

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What Is a Feet and Inches Calculator?

A Feet and Inches Calculator is an online tool that helps you quickly add, subtract, multiply, divide, or convert measurements expressed in feet and inches. If you work with imperial units, whether in construction, woodworking, DIY projects, interior design, architecture, or home improvement, this calculator removes the confusion of handling mixed measurements like 5 ft 7½ in or 3 ft 11.25 in.

Instead of doing awkward manual math with fractions, decimals, and base-12 conversions, the calculator gives you instant, accurate, and normalized results such as:

  • Total inches
  • Decimal feet
  • Clean feet-inch format

This makes it a globally useful tool that anyone can operate, from professionals to everyday users.

Understanding Feet and Inches: Why This Calculator Matters

Before using the calculator, it helps to understand how imperial measurements work. Unlike the metric system, which is based on powers of 10, the imperial system mixes base-12 and base-1 units. This makes manual calculations harder.

Feet and Inches Basics

  • 1 foot = 12 inches
  • Inches often include fractions (¼, ½, ¾) or decimals (0.25, 0.5, 0.75)
  • Measurements may come as:
    • Feet only (e.g., 5 ft)
    • Inches only (e.g., 40 in)
    • Mixed (e.g., 5 ft 8 in)
    • Decimal feet (e.g., 5.75 ft)
    • Fractional inches (e.g., 8 ½ in)
Visual ruler showing one foot divided into 12 inches with fractional markings at quarter-inch, half-inch, and three-quarter-inch intervals to demonstrate the base-12 imperial measurement system
Visual reference: 1 foot equals 12 inches with fractional divisions

Because of mixed unit types, converting manually can lead to errors, especially when adding multiple lengths, working with fractions, or converting to metric.

That's why the Feet and Inches Calculator is essential:

  • ✔ It handles conversions
  • ✔ Understands fractions
  • ✔ Avoids human error
  • ✔ Works globally
  • ✔ Normalizes results automatically
Diagram demonstrating measurement normalization where 18 continuous inches are automatically converted and split into 1 foot plus 6 inches format showing the calculator's normalization process
How normalization works: 18 inches becomes 1 foot 6 inches

Quick Conversion Reference Table

Below is a simple table that helps you understand the relationship between feet and inches:

Feet ⇄ Inches Conversion

Feet (ft)Inches (in)
1 ft12 in
2 ft24 in
3 ft36 in
4 ft48 in
5 ft60 in
6 ft72 in
7 ft84 in
8 ft96 in
9 ft108 in
10 ft120 in

Common Fraction to Decimal Inch Conversion

FractionDecimal Inch
1/8"0.125"
1/4"0.25"
3/8"0.375"
1/2"0.5"
5/8"0.625"
3/4"0.75"
7/8"0.875"

These conversion tables make it easier to understand what the calculator is doing behind the scenes.

Real-World Examples

Here are real-life scenarios showing how useful a Feet and Inches Calculator can be.

Example 1: Adding Two Board Lengths

A carpenter needs to add:

  • Board 1: 4 ft 8½ in
  • Board 2: 6 ft 3¼ in

What you enter:

  • 4 ft 8.5 in
  • 6 ft 3.25 in

Result:

  • 10 ft 11.75 in
  • Automatically normalized → 11 ft 0¾ in
  • Decimal feet → 11.0625 ft
  • Total inches → 132.75 in

This saves time and eliminates fraction mistakes.

Example 2: Converting Inches to Feet & Inches

A user has a measurement of 72 inches and wants to know the equivalent in feet.

Enter:

  • 0 ft
  • 72 in

Result:

  • 6 ft 0 in

Perfect for height, room sizes, and construction measurements.

Example 3: Multiplying Measurements for Area

You're calculating the size of a room:

  • Length: 15 ft 6 in
  • Width: 12 ft 4½ in

Conversions done by calculator:

  • 15 ft 6 in → 15.5 ft
  • 12 ft 4.5 in → 12.375 ft

Area:

  • 15.5 × 12.375 = 191.81 ft²

This is essential for flooring, tiles, painting, drywall, or renovation planning.

Conclusion

The Feet & Inches Calculator is an essential tool for anyone dealing with imperial measurements. Whether you're measuring wood, calculating room sizes, converting inches to feet, or working with fractions, this calculator gives you:

  • Instant results
  • Accurate conversions
  • Clean formatting
  • Fraction and decimal support
  • Metric output (optional)

With a simple interface and powerful calculation engine, it eliminates confusion and saves time for both professionals and everyday users.

References

To ensure accuracy and reliability, this calculator follows standard measurement conventions:

Frequently Asked Questions

Feet & Inches Calculator: Free Online Length Converter