The basic conversion: multiply feet by 12

To change feet to inches, multiply the number of feet by 12. Since one foot equals 12 inches, this is the only step you need. For example, 5 feet equals 60 inches (5 × 12 = 60).

This conversion matters in home projects because measurements often come in different units. A doorway might be listed as 6.5 feet tall, but you need to know it's 78 inches to order trim or frame a header correctly. Contractors and building materials suppliers sometimes use one unit or the other, so knowing how to switch between them keeps you from ordering the wrong size.

The reason you multiply by 12—not 10—is that the imperial system uses base-12 for feet and inches, not base-10 like decimals. This is why you can't just move a decimal point; you have to do the full multiplication every time.

Key Takeaways

  • Multiply the number of feet by 12 to get inches—this is the only calculation you need.
  • If you have a decimal (like 5.5 feet), multiply the whole number by 12, then multiply the decimal by 12 separately and add them together.
  • For measurements with feet and inches already mixed (like 5 feet 8 inches), just add the inches to your result—you already have the feet converted.
  • Keeping a calculator or conversion chart nearby during home projects saves time and prevents ordering mistakes.

Converting decimal feet to inches

When you have a decimal in your feet measurement—like 5.5 feet or 7.25 feet—multiply the entire number by 12. A calculator makes this faster and more accurate than doing it by hand.

For example, 5.5 feet × 12 = 66 inches. If you're working without a calculator, you can break it down: multiply the whole number (5) by 12 to get 60, then multiply the decimal (.5) by 12 to get 6, then add them (60 + 6 = 66).

Another example: 7.25 feet × 12 = 87 inches. Breaking it down: 7 × 12 = 84, then .25 × 12 = 3, then 84 + 3 = 87 inches. This method works for any decimal measurement you encounter.

Converting measurements that already mix feet and inches

Sometimes a measurement is already written as feet and inches together—for instance, 5 feet 8 inches. You don't need to convert the inches part; just convert the feet and add the inches that are already there.

Take 5 feet 8 inches: multiply 5 by 12 to get 60 inches, then add the 8 inches you already have. The total is 68 inches. This comes up often in home measurements—ceiling heights, door frames, and cabinet dimensions are frequently listed this way.

The key is recognizing that the inches are already in the right unit. You're only converting the feet portion, then combining the two numbers. This saves a step and prevents the common mistake of trying to convert the inches twice.

Why this matters for home projects

Building materials and tools are often labeled in inches, while room dimensions might be given in feet. If you're ordering flooring, trim, or shelving, the supplier might ask for measurements in inches. Knowing how to convert quickly prevents you from ordering a piece that's too short or too long.

Framing and drywall work also relies on inch measurements. Studs are spaced 16 inches or 24 inches apart, and if you're planning a wall layout, you'll need to think in inches to space them correctly. Converting feet to inches at the start of your project keeps all your math in one unit.

Door frames, window openings, and cabinet heights are typically measured in feet by contractors but ordered in inches from suppliers. Having this conversion down means you can move between what you measure and what you order without confusion.

Using a conversion chart or calculator

For common measurements, a simple chart can save time. Memorizing a few key conversions—like 1 foot = 12 inches, 2 feet = 24 inches, 3 feet = 36 inches, 4 feet = 48 inches—lets you estimate quickly on the job.

For anything beyond those basics, a calculator is faster and more reliable than mental math, especially when you're tired or working with decimals. Many smartphones have a built-in calculator app, and online converters work if you have internet access on site. Keep a small calculator in your toolbox for projects.

Common mistakes to avoid

The most common error is forgetting to multiply by 12 and just moving a decimal point instead. Feet and inches don't convert on a base-10 system—they convert on base-12, so moving a decimal gives you the wrong answer every time. For example, 5 feet is not 5.0 inches; it's 60 inches.

Another mistake is converting the inches part of a mixed measurement. If you see 6 feet 4 inches, convert only the 6 feet (to 72 inches) and then add the 4 inches you already have. Don't try to convert the 4 inches again. A third error is using the wrong multiplier—always use 12, never 10 or any other number.

Frequently Asked Questions

How do I convert 10 feet to inches?

Multiply 10 by 12. The answer is 120 inches. Use this same method for any whole number of feet.

What if I have a measurement like 3.75 feet?

Multiply 3.75 by 12. The answer is 45 inches. A calculator makes this easier than doing it by hand, especially with decimals.

Do I need to convert inches to feet for home projects?

Sometimes. If a measurement is given in inches but you need it in feet, divide by 12. For example, 60 inches ÷ 12 = 5 feet. Most home projects work fine staying in one unit throughout.

How do I handle fractions like 5 feet 6 inches?

Convert the feet (5 × 12 = 60) and add the inches (60 + 6 = 66 inches). Fractions written as feet and inches are already separated, so you just add them after converting the feet part.

Can I use an online converter instead of doing the math myself?

Yes. Online converters are fast and accurate, especially for decimal measurements. However, knowing how to do it yourself is useful when you don't have internet access on the job site.