Metric to imperial converter explained
Metric units are easy to scale, but many tools and specs still use inches, feet, and miles. This converter bridges common metric units (mm, cm, m, km) and imperial or US units, including a feet plus inches format for human measurements.
How the conversion works
The key exact relationship is:
1,textin=25.4,textmm
From there:
textin=fractextmm25.4
And feet follow from inches:
textft=fractextin12
Units and conversions
| Unit | Symbol | Relation |
|---|
| Millimeter | mm | 10−3,textm |
| Centimeter | cm | 10−2,textm |
| Meter | m | base unit |
| Kilometer | km | 1000,textm |
| Inch | in | 1,textin=25.4,textmm |
| Foot | ft | 1,textft=12,textin |
| Mile | mi | 1,textmi=5280,textft |
Worked examples
-
Converting 180 cm to inches
Convert cm to mm:
180,textcm=1800,textmm
Then mm to inches:
textin=frac180025.4=70.8661,textin
Result: 70.8661 in.
-
Converting 3 miles to kilometers
3,textmitimes1609.344,textm/mi=4828.032,textm
4828.032,textmdiv1000=4.828032,textkm
Result: 4.828032 km.
Tips and pitfalls
- For height, convert to feet plus inches instead of decimal feet; it reads better and avoids misinterpretation.
- Keep unit labels on your inputs; a number like 250 can be mm, cm, or inches depending on context.
- Rounding early is the fastest way to lose accuracy. Round once, at the end.
References and further reading