Metric to Inches Converter

What is the metric to inches converter?

The metric to inches converter turns a length given in a metric unit (millimeters, centimeters, or meters) into inches, and works in reverse too. Pick the metric unit from the dropdown, type a value, and the inches result appears instantly. Because the tool is bidirectional, you can also type a value into the inches field to read back the equivalent metric length.

The metric system is the everyday standard across most of the world, while the inch belongs to the imperial and US customary systems still common in the United States. Moving between the two is a routine task in manufacturing, woodworking, 3D printing, fashion, and any project that mixes parts or specifications from different regions.

How does the calculator work?

Every conversion is anchored to a single exact relationship:

$$1 \text{ in} = 25.4 \text{ mm}$$

The converter first reduces your metric input to a common base and then expresses it in inches. The per-unit factors are all derived from the definition above:

$$1 \text{ mm} = 0.0393701 \text{ in}, \quad 1 \text{ cm} = 0.393701 \text{ in}, \quad 1 \text{ m} = 39.3701 \text{ in}$$

To convert any metric length to inches, divide its value in millimeters by 25.4:

$$\text{Value in inches} = \frac{\text{Value in millimeters}}{25.4}$$

To go the other way, multiply the number of inches by 25.4 to get millimeters (then rescale to cm or m as needed):

$$\text{Value in millimeters} = \text{Value in inches} \times 25.4$$

Conversion table

Worked examples

From centimeters to inches

Suppose a tabletop edge measures 25.4 cm. Convert it to millimeters and divide by 25.4:

$$25.4 \text{ cm} = 254 \text{ mm}, \quad \frac{254}{25.4} = 10 \text{ in}$$

So 25.4 cm equals exactly 10 inches.

From meters to inches

A door is 1 m tall. Using the meter factor:

$$1 \text{ m} \times 39.3701 = 39.3701 \text{ in}$$

The door is about 39.37 inches tall.

From inches back to millimeters

You need 2 inches of clearance in a metric drawing:

$$2 \text{ in} \times 25.4 = 50.8 \text{ mm}$$

That is 50.8 mm, or 5.08 cm.

Practical notes and use cases

• 3D printing and CAD: Models are often dimensioned in millimeters, but hardware datasheets may list inches. Convert before slicing to avoid scaling errors.
• Woodworking and DIY: Lumber and fittings sold in inches frequently need to mesh with metric plans.
• Sewing and crafts: Patterns may quote centimeters while your ruler is marked in inches.
• Screens and displays: Diagonal sizes are quoted in inches even though panel specs are metric.

Because the 1 in = 25.4 mm relationship is exact by definition, conversions in either direction are precise; any rounding you see is only for display.

For single-unit conversions, see the mm to inches converter, the cm to inches converter, or the inches to meters converter.

Frequently asked questions

How many inches are in 1 meter?

There are 39.3701 inches in 1 meter, because 1 m = 1000 mm and 1000 / 25.4 = 39.3701 in.

How do you convert centimeters to inches?

Multiply the centimeter value by 0.393701, or equivalently divide the millimeter value by 25.4. For example, 30 cm = 300 mm = 11.811 in.

Is 1 inch exactly 25.4 mm?

Yes. Since 1959 the inch has been defined as exactly 25.4 millimeters, so the conversion is exact rather than approximate.

Can I convert inches back to metric units here?

Yes. The converter is bidirectional: type a value in the inches field and the equivalent metric length appears in the unit you selected (mm, cm, or m).

How many millimeters are in 4 inches?

$$4 \text{ in} \times 25.4 = 101.6 \text{ mm}$$

So 4 inches equal 101.6 mm.