Metric to Inches Calculator

Inches show up in hardware sizes, tool settings, and older drawings. Metric specs often use millimeters or centimeters. This calculator converts mm, cm, and meters to inches, and it also converts inches back to metric.

How the conversion works

The inch is defined exactly:

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

That gives a direct shortcut when your input is millimeters:

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

For centimeters, convert to millimeters first:

$$\text{mm} = 10 \times \text{cm}$$

Units and conversions

Worked examples

1. Converting 50 mm to inches

   $$\text{in} = \frac{50}{25.4} = 1.968504\,\text{in}$$

   Result: 1.968504 in.

2. Converting 2.54 cm to inches
   Convert to mm:

   $$2.54\,\text{cm} = 25.4\,\text{mm}$$

   Then:

   $$\text{in} = \frac{25.4}{25.4} = 1\,\text{in}$$

   Result: 1 in.

Tips and pitfalls

• For machining tolerances, keep at least four decimal places in inches during intermediate steps.
• Decide whether you need decimal inches or fractional inches; the math is the same, but the display differs.
• If you are converting a height or room dimension, feet can be a more readable reference than inches alone.

References and further reading

• International yard and pound agreement - Wikipedia
• Inch - Wikipedia