Quick reference table
| Tenths | Inches (decimal) | Nearest fraction | Millimetres |
|---|
How to convert tenths to inches
- Choose the kind of tenths on the tab above.
- Type the number. Decimals work, for example 3.5.
- Read the decimal inches, the nearest fraction, feet and inches, and millimetres. Change the fraction precision to match your tape or rule.
- To go the other way, switch the direction to Inches to tenths.
The formulas
| Type of tenths | Inches | Tenths |
|---|---|---|
| Tenths of an inch | inches = tenths × 0.1 | tenths = inches × 10 |
| Tenths of a foot | inches = tenths × 1.2 | tenths = inches ÷ 1.2 |
| Machinist tenths | inches = tenths × 0.0001 | tenths = inches × 10,000 |
To get millimetres, multiply inches by 25.4. The inch is defined as exactly 25.4 mm.
Worked examples
Example 1: 25 tenths of an inch. 25 × 0.1 = 2.5 in, which is 2 1/2 in or 63.5 mm.
Example 2: 3.5 tenths of a foot. 3.5 × 1.2 = 4.2 in. The nearest 1/64 fraction is 4 13/64 in (4.2031 in), about 106.68 mm. As feet and inches that is 0 ft 4.2 in.
Example 3: 12.4 feet, written as feet and tenths. The 0.4 ft part is 4 tenths of a foot = 4.8 in, so the length is 12 ft 4.8 in.
Example 4: 25 machinist tenths. 25 × 0.0001 = 0.0025 in, which is 2.5 thou or 0.0635 mm.
Where each kind is used
- Tenths of an inch: some shop, packaging and gauge readings that use decimal inches.
- Tenths of a foot: drawings and survey notes written in feet and decimals, such as 12.4 ft.
- Machinist tenths: tolerances on machined parts, where "hold it to a tenth" means 0.0001 in. A micrometer or indicator that reads in 0.0001 in steps shows tenths directly.
If a drawing does not state which one it means, check its title block or ask the person who made it before you cut.
Frequently asked questions
How many inches is 1 tenth?
It depends on the unit. One tenth of an inch is 0.1 in. One tenth of a foot is 1.2 in. One machinist tenth is 0.0001 in.
How do I convert tenths of a foot to feet and inches?
Multiply the decimal part of the foot by 12. For 12.4 ft, 0.4 × 12 = 4.8 in, so it is 12 ft 4.8 in.
How many tenths are in an inch?
There are 10 tenths of an inch in an inch, 10,000 machinist tenths, and 10 ÷ 1.2 = 8.33 tenths of a foot.
Why is the fraction sometimes "about"?
A decimal such as 4.2 in does not land exactly on a fraction of 1/64. The tool shows the nearest fraction for the precision you picked and how far off it is.
Is the result accurate enough to cut or machine from?
The arithmetic is exact to the digits shown. Real parts also depend on your tool, tolerance and the drawing, so check critical dimensions with the original specification.