Millimeters to Inches
Convert millimeters to inches and decimals. 1 mm = 0.0393701 inches.
About This Calculator
Convert millimeters to inches and decimals. 1 mm = 0.0393701 inches. Use the calculator above for instant results.
Worked Examples
Example 1: 25 mm
- 25 / 25.4 = 0.9843 inches (close to 1 inch)
Answer: 0.9843 inches
Example 2: 100 mm (10 cm)
- 100 / 25.4 = 3.937 inches
Answer: 3.937 inches
Example 3: 25.4 mm
- Exactly 1 inch (1 in = 25.4 mm exactly)
Answer: 1 inch
Who Uses This Calculator?
Engineers
Precision measurements in metric.
Builders
Convert plans between systems.
Machinists
Metric to imperial precision.
Scientists
Research measurement conversion.
Common Mistakes to Avoid
❌ 1 inch = 25.4 mm exactly
This is the exact defined relationship. Very useful to remember.
❌ mm vs cm
10 mm = 1 cm. Millimeters are smaller — use for precision measurements.
Frequently Asked Questions
mm to inches formula?
Divide by 25.4. 1 mm = 0.03937 inches.
Inches to mm?
Multiply by 25.4. 1 inch = 25.4 mm.
How many mm in a foot?
304.8 mm exactly (12 × 25.4).