Inches Per Hour Converter
Rain at 1 inch per hour is a very heavy downpour, and it equals 25.4 mm each hour.
Quick answer: Multiply the speed in in/h by 0.00705556 to get mm/s. For example, 1 in/h is 0.007056 mm/s, 10 in/h is 0.0706 mm/s and 100 in/h is 0.7056 mm/s.
The inches per hour to mm/s formula
Speed in millimetres per second equals speed in inches per hour times 0.007055556.
The factor 0.00705556 is 25.4 divided by 3,600, the mm in an inch over the seconds in an hour.
Take 1 in/h. 1 × 0.007055556 gives 0.007056 mm/s.
Take 10 in/h. 10 × 0.007055556 gives 0.0706 mm/s.
Inches per hour and millimetres per second
An inch per hour is a very slow speed. It is used for rain rates, for crack or creep checks and for slow growth.
A millimetre per second is a metric unit, so the result is a small decimal.
How to convert inches per hour to mm/s step by step
- Write down the speed in inches per hour.
- Multiply it by 0.007055556.
- Round to the digits you need.
- Write the unit mm/s after the answer.
Example 1: 1 in/h
- Start with 1 in/h.
- 1 × 0.007055556 = 0.007056.
- The speed is 0.007056 mm/s.
1 in/h = 0.007056 mm/s
Example 2: 10 in/h
- Start with 10 in/h.
- 10 × 0.007055556 = 0.0706.
- The speed is 0.0706 mm/s.
10 in/h = 0.0706 mm/s
Example 3: 100 in/h
- Start with 100 in/h.
- 100 × 0.007055556 = 0.7056.
- The speed is 0.7056 mm/s.
100 in/h = 0.7056 mm/s
Round only at the end. Rounding in the middle of a sum adds small errors that grow.
inches per hour to mm/s conversion table
| inches per hour (in/h) | millimetres per second (mm/s) | in/min |
|---|---|---|
| 0.5 in/h | 0.003528 mm/s | 0.008333 in/min |
| 1 in/h | 0.007056 mm/s | 0.0167 in/min |
| 2 in/h | 0.0141 mm/s | 0.0333 in/min |
| 5 in/h | 0.0353 mm/s | 0.0833 in/min |
| 10 in/h | 0.0706 mm/s | 0.1667 in/min |
| 25 in/h | 0.1764 mm/s | 0.4167 in/min |
| 50 in/h | 0.3528 mm/s | 0.8333 in/min |
| 100 in/h | 0.7056 mm/s | 1.667 in/min |
| 250 in/h | 1.764 mm/s | 4.167 in/min |
| 500 in/h | 3.528 mm/s | 8.333 in/min |
| 1,000 in/h | 7.056 mm/s | 16.667 in/min |
The highlighted row is the default of the calculator. The last column gives in/min.
A quick mental shortcut for inches per hour to mm/s
For quick work, multiply by 0.007. 1,000 in/h × 0.007 = 7 mm/s, and the exact answer is 7.06.
To get mm per hour instead, multiply by 25.4. 10 in/h is 254 mm/h.
Slow rates
A rate of 0.5 in/h is 12.7 mm/h, or 0.00353 mm/s. A rate of 2 in/h is 50.8 mm/h.
Because the numbers are small, many people use mm per hour or per day.
More values at a glance
0.5 inches per hour is 0.0035 millimetres per second. 2 inches per hour is 0.0141 millimetres per second. 5 inches per hour is 0.0353 millimetres per second.
10 inches per hour is 0.0706 millimetres per second. 25 inches per hour is 0.1764 millimetres per second. 100 inches per hour is 0.7056 millimetres per second.
Each answer is the input times 0.0071. You can use the same factor for any value that is not listed here.
The unit sizes
One of the inches per hour equals 0.0071 millimetres per second. One of the millimetres per second equals 141.7323 inches per hour.
If a result looks very large or very small, compare it with these sizes before you use it.
Checking in reverse
Take 0.0706 millimetres per second and divide by 0.0071. You get back 10 inches per hour. If you do not, one of the numbers was typed or rounded wrongly.
More conversions in a row
0.1 inches per hour is 7.0556 × 10⁻⁴ millimetres per second. 0.25 inches per hour is 0.0018 millimetres per second. 1 inches per hour is 0.0071 millimetres per second.
3 inches per hour is 0.0212 millimetres per second.
7 inches per hour is 0.0494 millimetres per second. 15 inches per hour is 0.1058 millimetres per second. 40 inches per hour is 0.2822 millimetres per second.
60 inches per hour is 0.4233 millimetres per second.
75 inches per hour is 0.5292 millimetres per second. 150 inches per hour is 1.0583 millimetres per second. 200 inches per hour is 1.4111 millimetres per second.
500 inches per hour is 3.5278 millimetres per second.
Rounding the factor
The factor 0.0071 is long. If you cut it to 0.0071, 100 inches per hour becomes 0.706 millimetres per second instead of 0.7056.
That is an error of about 0.063 percent, which is fine for a rough check but not for exact work.
Doubling and scaling
The conversion is a straight line through zero. Double the speed in inches per hour and the speed in millimetres per second doubles too.
So 20 inches per hour is 0.1411 millimetres per second, and 40 inches per hour is 0.2822 millimetres per second. You can build any value from the ones in the table.
Quick conversion answers
| Conversion | Result |
|---|---|
| 1 in/h | 0.007056 mm/s |
| 5 in/h | 0.0353 mm/s |
| 10 in/h | 0.0706 mm/s |
| 50 in/h | 0.3528 mm/s |
| 100 in/h | 0.7056 mm/s |
| 500 in/h | 3.528 mm/s |
Where this conversion is used
Weather writers convert rain rates from inches per hour into metric units.
Engineers watching slow creep or settling in a structure use small speeds like this.
Common mistakes to avoid
- Forgetting the 3,600. An hour has 3,600 seconds, so the mm/s figure is tiny.
- Using 25.4 alone. That gives mm per hour, not mm per second.
- Mixing in/h with in/min. They differ by a factor of 60.
- Rounding too hard. The result is small, so keep at least four digits.
Related converters
Frequently asked questions
How many millimetres per second is 1 in/h?
1 in/h is 0.007055556 mm/s.
How many millimetres per second is 10 in/h?
10 in/h is 0.0705556 mm/s.
How many inches per hour is 1 mm/s?
1 mm/s is 141.7323 in/h.
How many mm/s is 1 in/h?
It is about 0.00705556 mm/s.
How many mm per hour is 1 in/h?
It is exactly 25.4 mm/h.
Is the factor exact?
Yes. The inch is exactly 25.4 mm and an hour is exactly 3,600 s.
Sources
- CASRAI: The metre (casrai.org)
