Metric to Inches Calculator

Q: How many inches is 1 cm?

1 cm = 0.3937 inches , a little over 3/8 of an inch. Quick ones to remember: 2.54 cm = 1 inch 10 cm = 3.937 inches (about 4 in) 100 cm = 39.37 inches

Q: How many millimeters is 1/8 of an inch?

1/8 in = 3.175 mm . Here are the common ones: 1/64 in = 0.397 mm 1/32 in = 0.794 mm 1/16 in = 1.588 mm 1/8 in = 3.175 mm 1/4 in = 6.35 mm 1/2 in = 12.7 mm

Q: What fraction on a tape measure is closest to 1 cm?

1 cm is 0.3937 in, which is closest to 3/8 in (0.375 in). The gap is about 0.02 in, or half a millimeter. For a tighter match, 25/64 in (0.3906 in) is even closer, but most tapes do not show 64ths.

Q: How many centimeters are in a foot?

1 foot = 30.48 cm , since 12 × 2.54 = 30.48. That is why a 30 cm ruler is just a bit shorter than a foot ruler, by about 5 mm.

Metric to Inches Calculator

Introduction

This Metric to Inches Calculator changes metric lengths into inches. Type a number, pick millimeters (mm), centimeters (cm), meters (m), or kilometers (km), and the answer appears as you type.

You see the length four ways: decimal inches, fraction inches, feet and inches, and yards. You pick how exact the fraction is, from a whole inch down to 1/64 of an inch. You also pick how many decimal places to show.

The tool works both ways. The second panel turns inches back into mm, cm, m, or km. Below that, a step-by-step solution shows the math, so you can check the work or learn how it is done. A chart and a table of common conversions, like 1 m to inches and 30 cm to inches, let you compare sizes side by side.

All math uses the exact rule: 1 inch = 25.4 mm. That makes it useful for school work, sewing, woodworking, building, and shipping sizes.

How to use our Metric to Inches Calculator

Type a metric length like millimeters, centimeters, meters, or kilometers, and the calculator shows the answer in decimal inches, fraction inches, feet and inches, decimal feet, and yards. You can also go the other way and turn inches into metric units.

Fractional inch precision: Pick how exact you want the fraction, from a whole inch down to 1/64 of an inch. This choice shapes every fraction and feet-and-inches answer.

Decimal places: Choose how many numbers show after the decimal point, from 1 to 6. Use fewer for quick jobs and more for fine work.

Metric value: Enter the length you want to change to inches. You can use decimals, minus signs, or science notation like 2.5e3.

Source unit: Tap mm, cm, m, or km to tell the tool what unit your metric number is in.

Inches: In the right panel, type an inch value like 12.5 to turn it into metric. This panel works on its own.

Metric output unit: Pick millimeters, centimeters, meters, or kilometers for that inch answer. A summary line shows all four units at once.

Press Calculate to refresh the results, or Reset to start over. Click any row in the conversion chart to load that metric length, and use the copy buttons to grab an answer.

Metric to Inches Conversion Explained

Most of the world measures length with the metric system: millimeters (mm), centimeters (cm), meters (m), and kilometers (km). The United States mostly uses inches, feet, and yards. Converting metric to inches lets you compare the two systems so sizes match, whether you are cutting wood, buying a TV, or reading a plan from another country.

The Key Number: 25.4

One inch is exactly 25.4 millimeters. That number is not rounded. It is the official definition agreed on in 1959. Every metric to inch conversion comes from it. To change any metric length into inches, turn it into millimeters first, then divide by 25.4.

Simple Conversion Facts

1 inch = 25.4 mm = 2.54 cm = 0.0254 m
1 mm = 0.03937 inches
1 cm = 0.3937 inches
1 m = 39.3701 inches = 3.2808 feet
1 km = 39,370.1 inches = 1,093.6 yards
12 inches = 1 foot, 36 inches = 1 yard

Decimal Inches vs. Fractional Inches

Engineers and machinists often write inches as decimals, like 3.9370 in. Builders, carpenters, and tape measures use fractions, like 3 15/16 in. Both mean the same length. Fractions are rounded to the nearest 1/2, 1/4, 1/8, 1/16, 1/32, or 1/64 of an inch. Smaller fractions give a closer answer, but they are harder to read on a ruler. For woodworking, 1/16 in is usually close enough. For metal work, 1/32 or 1/64 in is common.

Why Feet and Inches Matter

Long metric lengths turn into large inch numbers that are hard to picture. That is why a person's height or a room's size is written as feet and inches in the U.S. For example, 180 cm is about 70.87 inches, which reads better as 5 ft 10 7/8 in.

Handy Sizes to Remember

25 mm is just under 1 inch
10 cm is about 4 inches
30 cm is about 1 foot (a bit shorter)
1 meter is a little longer than 1 yard
A4 paper (210 × 297 mm) is about 8.27 × 11.69 inches

Watch Out for Rounding

Rounding too early can throw off a project. If you round 2.54 cm to 1 inch on a short piece, no problem. Do it ten times in a row and the error adds up. Keep extra decimal places while you work, and round only at the very end when you mark or cut.

Formulas used

Metric value to millimeters

\text{mm} = v \times f_u, \quad f_{mm}=1,\; f_{cm}=10,\; f_{m}=1000,\; f_{km}=1000000

Millimeters to inches

\text{in} = \frac{\text{mm}}{25.4}

Inches to decimal feet

\text{ft} = \frac{\text{in}}{12}

Inches to yards

\text{yd} = \frac{\text{in}}{36}

Rounding to the nearest 1/d inch

\text{in}_{frac} = \frac{\operatorname{round}(|\text{in}| \times d)}{d}

Feet and inches breakdown

F = \left\lfloor \frac{\operatorname{round}(|\text{in}|\times d)}{12d} \right\rfloor, \quad I = \frac{\operatorname{round}(|\text{in}|\times d) - 12dF}{d}

Inches to metric unit (reverse)

m_u = \frac{\text{in} \times 25.4}{f_u}

Frequently asked questions

How many inches is 1 cm?

1 cm = 0.3937 inches, a little over 3/8 of an inch.

Quick ones to remember:

2.54 cm = 1 inch
10 cm = 3.937 inches (about 4 in)
100 cm = 39.37 inches

How do you convert cm to inches in your head?

Divide the centimeters by 2.5. That gets you close fast.

Example: 50 cm ÷ 2.5 = 20 inches. The real answer is 19.69 inches, so you are off by about 1.5%.

For a closer guess, take the cm number, divide by 2.5, then take away 1.5% of it.

Why is an inch exactly 25.4 mm?

In 1959, the United States, the United Kingdom, Canada, and other countries signed an agreement to set one inch at exactly 25.4 mm. Before that, each country used a slightly different inch, and parts did not always fit.

Because the number is a definition and not a measurement, it never gets rounded. Every metric-to-inch answer starts from it.

How do you convert centimeters to feet and inches?

Three steps:

Divide the cm by 2.54 to get total inches.
Divide the inches by 12. The whole number is the feet.
What is left over is the inches.

Example: 180 cm ÷ 2.54 = 70.87 in. 70.87 ÷ 12 = 5 feet, with 10.87 inches left. So 180 cm = 5 ft 10 7/8 in.

How do you turn a decimal inch into a fraction?

Multiply the decimal part by the bottom number you want, round to a whole number, then reduce.

Example: 3.9370 in to the nearest 1/16.

0.9370 × 16 = 14.99, round to 15
Answer: 3 15/16 in

Use 16 for wood, 32 or 64 for metal work.

How many millimeters is 1/8 of an inch?

1/8 in = 3.175 mm. Here are the common ones:

1/64 in = 0.397 mm
1/32 in = 0.794 mm
1/16 in = 1.588 mm
1/8 in = 3.175 mm
1/4 in = 6.35 mm
1/2 in = 12.7 mm

What do the ' and " marks mean in measurements?

One mark (') means feet. Two marks (") mean inches.

So 5' 10" is read as 5 feet 10 inches. You may also see it written 5 ft 10 in.

Is a meter longer than a yard?

Yes. 1 meter = 39.37 inches and 1 yard = 36 inches, so a meter is 3.37 inches longer.

That is about 9% more. Over 10 meters, the gap grows to almost 2 feet 9 inches, so do not treat them as the same for fabric or flooring.

What fraction on a tape measure is closest to 1 cm?

1 cm is 0.3937 in, which is closest to 3/8 in (0.375 in). The gap is about 0.02 in, or half a millimeter.

For a tighter match, 25/64 in (0.3906 in) is even closer, but most tapes do not show 64ths.

How many centimeters are in a foot?

1 foot = 30.48 cm, since 12 × 2.54 = 30.48.

That is why a 30 cm ruler is just a bit shorter than a foot ruler, by about 5 mm.

What size is a 55-inch TV in centimeters?

A 55-inch TV measures 139.7 cm across the screen corner to corner, not side to side.

Other common sizes: 32 in = 81.3 cm, 43 in = 109.2 cm, 65 in = 165.1 cm, 75 in = 190.5 cm. The full frame is usually a few cm wider, so check the box before you buy a stand.

Are American inches and British inches the same size?

Yes, since 1959 both are exactly 25.4 mm. Before that they differed by a tiny amount.

One odd case is left: the U.S. survey foot, used in old land records, is a hair longer than the normal foot. It matters only over long distances, like miles of land, not for building or sewing.

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