Feet and Inches Calculator

Using the calculator is straightforward. Depending on what you need, you can switch between a few different modes.

• Convert feet to inches: Enter a value in feet and get the equivalent number of inches.
• Convert inches to feet: Enter inches and see the result in feet, either as a decimal or in feet-and-inches format.
• Add or subtract measurements: Input two measurements in feet and inches and the calculator will combine or subtract them, giving you a clean result.

Most fields accept decimals, so you're not limited to whole numbers. If you're working with something like 5.75 feet or 33.5 inches, just type it right in. The calculator handles the rest.

The core relationship here is simple: one foot equals exactly 12 inches. That's the foundation of every conversion in the imperial system of length.

To convert any measurement in feet to inches, multiply the number of feet by 12.

• 2 feet = 2 × 12 = 24 inches
• 5 feet = 5 × 12 = 60 inches
• 6.5 feet = 6.5 × 12 = 78 inches

If your measurement is already in feet and inches, convert only the feet portion and then add the remaining inches. So 5 feet 9 inches becomes (5 × 12) + 9 = 60 + 9 = 69 inches total.

Going the other direction is just as easy. Divide the number of inches by 12 to get feet.

The tricky part is that the result often isn't a whole number. You have two options for expressing it: as a decimal or as feet and inches.

• Decimal format: 54 inches ÷ 12 = 4.5 feet
• Feet and inches format: 54 ÷ 12 = 4 with a remainder of 6, so 4 feet 6 inches

To find the remainder, multiply the whole number part of your decimal result by 12 and subtract from the original. For 58 inches: 58 ÷ 12 = 4.833... The whole number is 4, and 4 × 12 = 48. So 58 - 48 = 10 inches remaining. That gives you 4 feet 10 inches.

Adding or subtracting mixed measurements trips people up more than it should. The key is to handle feet and inches separately, then adjust if the inches go over 12 or drop below zero.

To add feet and inches:

1. Add the feet together.
2. Add the inches together.
3. If the total inches are 12 or more, convert the excess to feet. For example, 16 inches becomes 1 foot 4 inches, so you add 1 to the foot total and keep 4 as the remaining inches.

Example: 3 feet 8 inches + 2 feet 7 inches

• Feet: 3 + 2 = 5
• Inches: 8 + 7 = 15 (which is 1 foot 3 inches)
• Result: 5 + 1 = 6 feet 3 inches

To subtract: Follow the same column approach. If the inches in the second number are larger than the first, borrow 1 foot (12 inches) from the foot total and add it to the first inches value before subtracting.

Example: 5 feet 3 inches - 2 feet 9 inches

• You can't subtract 9 from 3, so borrow 1 foot: 5 becomes 4 feet, and 3 inches becomes 15 inches.
• Inches: 15 - 9 = 6
• Feet: 4 - 2 = 2
• Result: 2 feet 6 inches

The formulas behind the calculator aren't complicated. Here's a quick reference for the most common conversions.

The floor function just means round down to the nearest whole number. And mod (modulo) gives you the remainder after division. For most everyday purposes, you don't need to think about either of those terms. The calculator applies them automatically. But if you ever need to do this by hand, those are the building blocks.

Here are a few practical scenarios where this kind of math comes up regularly.

• Height: A person who is 5 feet 11 inches tall is (5 × 12) + 11 = 71 inches tall.
• Room dimensions: A wall that measures 144 inches across is 144 ÷ 12 = 12 feet wide.
• Lumber and trim: You need two pieces of baseboard, one at 3 feet 4 inches and another at 2 feet 10 inches. Combined, that's 3+2=5 feet and 4+10=14 inches, which simplifies to 6 feet 2 inches total.
• Vertical clearance: A doorway is 80 inches tall. That converts to 80 ÷ 12 = 6 feet 8 inches, which is the standard door height in the US.
• Fabric and materials: 4.5 feet of fabric equals 4.5 × 12 = 54 inches, a common measurement in textile widths.

These are the kinds of problems that come up in construction, interior design, shopping for furniture, and a dozen other everyday situations. Getting comfortable with the conversion makes all of them faster.

There are actually three ways to express the same measurement, and each has its place depending on the context.

Feet and inches is the format most people are familiar with in the US. It's how height is talked about, how tape measures are typically read, and how contractors communicate on job sites.

Inches only is common in product specifications. TV screen sizes, mattress dimensions, and monitor sizes are all expressed in inches because the numbers feel more concrete and consistent.

Decimal feet shows up in engineering and surveying, where you're doing a lot of arithmetic and fractions would slow things down. If you're entering measurements into a spreadsheet or a CAD program, decimal feet is usually the way to go.

The United States is one of the very few countries that still uses the imperial system in everyday life. Feet and inches are deeply embedded in American culture, construction, and commerce, even as metric has taken hold in science and medicine.

Historically, both feet and inches were derived from human body proportions. A foot was roughly the length of a human foot. An inch was based on the width of a thumb or, in some traditions, three dried barleycorns laid end to end. These weren't arbitrary choices. They were practical reference points that anyone could relate to without a measuring device.

Today, feet and inches stick around for a few reasons. Building codes, property records, and architectural drawings in the US are all standardized in imperial units. The construction industry has generations of workers trained in feet and inches, and retooling that would cost an enormous amount of time and money. Consumer products, from mattresses to lumber, are sold in foot and inch dimensions. And for everyday communication, most Americans simply think in these units naturally.

Whether you prefer metric or imperial, understanding how to work with feet and inches is a genuinely useful skill if you live in or work with the US market.