Tenths to Inches Calculator
Enter a size in tenths, thou, mil, inches, microinches or millimetres to see it in every other unit, with the inch value in decimals.
The Tenths to Inches Calculator converts a machining size given in tenths, thou, mils, inches, tenths of an inch, microinches, millimetres or micrometres into every other unit at once. Enter a value, pick its unit, and the decimal inch and millimetre results appear right away, along with the tenths, thou and microinch equivalents. It runs in your browser, is free, and needs no sign-up.
Machinists and inspectors often switch between these units, especially when a drawing gives tolerances in one unit and a gauge reads in another. The tool handles the arithmetic so you can check a value quickly before you cut, measure or write a quote. It also works on a phone, so you can use it at the machine.
How to use the Tenths to Inches Calculator
- Type the size into the Value box. Negative values are accepted, which is useful for deviations.
- Open the Unit list and choose the unit your size is written in. The options are Tenths (0.0001 in), Thou or mil (0.001 in), Inches, Tenths of an inch (0.1 in), Microinches (µin), and Millimetres or Micrometres (µm).
- Read the two large rows, Inches (decimal) and Millimetres. These are the main answers.
- Scroll to the smaller rows for Tenths (0.0001 in), Thou or mil (0.001 in), Tenths of an inch (0.1 in), Microinches and Micrometres.
- If a warning appears, read it before you use the number. The tool warns when you choose Tenths of an inch, because shop talk “tenths” usually means 0.0001 in. It also warns when you enter 1,000 or more tenths.
Results update as you type, so you can change the value and watch the rows change. Open How it was calculated to see the formula and each step using your numbers.
The four preset buttons (5 tenths, 25 thou, 0.01 mm and 0.0005 in) fill in common values for you. Use Copy result to copy the result lines with a link, or Copy link to copy the page address, which stores your inputs so the same calculation reopens later. Print / save as PDF prints the inputs, results, calculation steps and the date.
What is a tenth in machining?
In machining, a tenth is 0.0001 inch, one ten-thousandth of an inch. Shop talk uses it for fine tolerances and gauge readings. For example, five tenths is 0.0005 in, and the tool converts that to 0.0127 mm.
Machinists often drop the word “inch” and say “two tenths” when they mean 0.0002 in. One microinch is 0.000001 in, so one tenth equals 100 microinches. In metric terms, 1 in is exactly 25.4 mm, so one tenth is 0.00254 mm, or 2.54 µm.
How many tenths are in a thou?
A thou is 0.001 inch, and it is also called a mil, especially in North America. Since one tenth is 0.0001 in, a thou holds exactly 10 tenths. Put the other way round, the thou is the easiest unit to picture when you read a tolerance written in tenths, such as 25 thou being 250 tenths.
The metric size of a thou follows from the same exact conversion. Because 1 in is 25.4 mm, one thou is 0.0254 mm. The tool keeps all of these in step, so you do not need to multiply by hand.
How do you convert tenths to inches?
Multiply the number of tenths by 0.0001. Five tenths is 5 × 0.0001 = 0.0005 in. To go the other way, divide the inch value by 0.0001: a tolerance of 0.0012 in is 12 tenths.
To get millimetres, multiply the inches by 25.4. Five tenths is 0.0005 × 25.4 = 0.0127 mm, or 12.7 µm. For thou, multiply by 0.001 for inches: 25 thou is 0.025 in, which is 0.635 mm or 250 tenths.
How do you convert mm to tenths?
Divide the millimetres by 25.4 to get inches, then divide by 0.0001. A 0.01 mm tolerance is 0.01 ÷ 25.4 = 0.000394 in, or about 3.94 tenths. Choose Millimetres in the Unit list and the Tenths row shows the answer directly.
Sources
- Thousandth of an inch (Wikipedia) — a thou (mil) is 0.001 in; in machining 0.0001 in is one “tenth”
- 1 in = 25.4 mm exactly (NIST SP 811); 1 µin = 0.000001 in
Worked examples
| Input | Result |
|---|---|
| 5 Tenths (0.0001 in) | 0.0005 in = 0.0127 mm = 5 tenths |
| 25 Thou or mil (0.001 in) | 0.025 in = 0.635 mm = 250 tenths |
| 0.0005 Inches | 0.0005 in = 0.0127 mm = 5 tenths |
| 0.01 Millimetres | 0.000393701 in = 0.01 mm = 3.93701 tenths |
| 3 Tenths of an inch (0.1 in) | 0.3 in = 7.62 mm = 3000 tenths |
Calculated by the tool above with these values.
Frequently asked questions
How many tenths are in an inch?
There are 10,000 tenths in one inch, since each tenth is 0.0001 in. Enter 1 with the Inches unit and the Tenths (0.0001 in) row shows 10,000.
How do you convert mil to inches?
Divide the number of mils by 1,000. One mil is 0.001 in, so 25 mil is 0.025 in. To convert mils to millimetres, multiply the mil value by 0.0254, which gives 0.635 mm for 25 mil.
What does tenths of an inch mean?
In plain decimal talk, “tenths of an inch” means 0.1 in. This is a different unit from shop-talk tenths. For example, 3 tenths of an inch is 0.3 in, which is 7.62 mm, or 3000 shop-talk tenths. Choose Tenths of an inch (0.1 in) in the Unit list only when you mean the larger value.
How do I convert 10ths to inches?
Choose the Tenths (0.0001 in) unit and enter 10. The Inches (decimal) row shows 0.001 in, because 10 tenths equals one thou.
Can the tool convert fractions of an inch?
No. The tool works with decimal inches, tenths, thou, microinches and metric units only. For fractions, use the Decimal to fraction inches page, which converts decimal inch values to fractions.
Can I enter a negative value?
Yes. Negative values are accepted, so you can enter a deviation such as -5 tenths and read its equivalent in inches and millimetres.
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