To convert millihenries to henries, multiply by 0.001. That factor is the whole relationship: both units measure how strongly a coil opposes a change in current, so the conversion is a proportion with no offset and no substance-specific constant.
The henry is the SI unit of inductance: one volt induced per amp-per-second change in current. Millihenries cover audio crossovers, relay coils and the smoothing chokes in linear supplies.
Below the calculator there is a step table for the values people look up most, and a second table putting real how strongly a coil opposes a change in current figures into henries so the number you get has something to be compared against.
The formula
millihenries- The amount you are converting, in millihenries
0.001- The exact number of henries in one millihenry
henries- The converted result
How it works, step by step
- Enter the value in millihenries.
- It is multiplied by 0.001, the exact factor between the two units.
- The answer is shown in henries, with the reverse conversion beneath it.
- Check the reference table if you want a figure of comparable size.
Worked examples
Mains transformer primary: 5000 mH in henries
Mains transformer primary comes to about 5000 mH. Multiplying by the factor: 5000 × 0.001 = 5 H. Dividing the answer back by 0.001 returns the figure you started with, which is the quickest way to check you have the factor the right way up.
Buck converter inductor: 0.047 mH in henries
Take buck converter inductor, roughly 0.047 mH. The conversion is a single multiplication — 0.047 × 0.001 — giving 4.7e-05 H. Because the relationship is proportional, doubling the input doubles the answer to 9.4e-05 H.
How to read your score
Frequently asked questions
How many henries are in one millihenry?
Exactly 0.001. Every figure on this page is that one number multiplied by your input, so the only rounding is at the display step.
What is the formula to convert millihenries to henries?
henries = millihenries × 0.001. Reversed, millihenries = henries ÷ 0.001, which is the same as multiplying by 1000.
Which is the bigger unit, the millihenry or the henry?
The henry. One millihenry is only 0.001 of a henry, so it takes 1000 millihenries to make one henry.
What does this quantity actually measure?
Both units measure how strongly a coil opposes a change in current. That is why a single factor is enough: there is no temperature offset and no material property involved, unlike conversions that cross between different quantities.
What is a millihenry?
Millihenries cover audio crossovers, relay coils and the smoothing chokes in linear supplies.
What is a henry?
The henry is the SI unit of inductance: one volt induced per amp-per-second change in current.
Why does my answer differ from another converter?
Almost always because the other tool rounded the factor before multiplying. This page keeps full double precision through the calculation and rounds only for display, and it prints the factor it used so you can see where any difference came from.
Millihenries to henries reference tables
| Millihenries | Henries |
|---|---|
| 0.5 mH | 0.0005 H |
| 1 mH | 0.001 H |
| 2 mH | 0.002 H |
| 3 mH | 0.003 H |
| 5 mH | 0.005 H |
| 10 mH | 0.01 H |
| 20 mH | 0.02 H |
| 25 mH | 0.025 H |
| 50 mH | 0.05 H |
| 75 mH | 0.075 H |
| 100 mH | 0.1 H |
| 250 mH | 0.25 H |
| 500 mH | 0.5 H |
| 1000 mH | 1 H |
| 5000 mH | 5 H |
Exact factor: 1 millihenry = 0.001 henries.
| Quantity | mH | H |
|---|---|---|
| PCB trace, 25 mm | 2e-05 mH | 2e-08 H |
| RF choke | 0.01 mH | 1e-05 H |
| Buck converter inductor | 0.047 mH | 4.7e-05 H |
| Speaker crossover coil | 1.5 mH | 0.0015 H |
| Relay coil | 100 mH | 0.1 H |
| Mains transformer primary | 5000 mH | 5 H |
Published reference values, converted with the same factor this page uses.