Given its status as a fundamental property of circuit design with implications for such aspects as component design, system performance, and signal integrity, it is fair to say inductance is a vital concept for engineers to understand.
Across such applications as transformers, filters, and energy storage, inductance plays a major role. But it isn’t merely the principles of what inductance is that engineers need to be knowledgeable in and confident about.
That’s because the ability to convert units of inductance measurement, such as Henries, as well as either smaller or larger units like millihenries (mH), microhenries (µH), and kilohenries (kH), will also be of profound importance.
Introducing The Concept of Inductance
Inductance can be defined as the property of a conductor – typically a coil – that resists changes in current flow. It is brought about by the electromagnetic field that is generated around the conductor when current passes through it.
Why Is It So Vital for Engineers to Convert Inductance Units?
As an engineer, you are likely to need to convert scales of inductance from time to time for a variety of reasons.
Instead of allowing yourself to be confused by the fact that inductance may be expressed in, for instance, Henries in one context and microhenries in another, you might simply convert these units to help ensure consistency and accuracy in your calculations.
Skipping any such conversion work – leaving values expressed in varying units of inductance measurement – could heighten the scope for confusion and damaging mistakes across your projects. You won’t, for example, want to end up with undersized or oversized components relative to your actual requirements.
A Summary of The Common Units of Inductance Measurement
The SI base unit for measuring inductance is the Henry, named in honour of the physicist Joseph Henry (1797-1878).
One Henry is, in the words of Britannica, “the value of self-inductance in a closed circuit or coil in which one volt is produced by a variation of the inducing current of one ampere per second.”
Other units of inductance measurement include the microhenry, millihenry, kilohenry, picohenry, (pH) and nanohenry (nH).
How Can You Convert Between These Scales of Inductance?
An obvious answer to this question might be, “simply find a useful inductance calculator online”. Sure enough, various calculation tools like this are easy enough to find, and they enable you to quickly convert one unit of inductance measurement to another.
Such tools certainly have their part to play in helping to speed up circuit design projects. Furthermore, it is good practice to routinely perform manual calculations alongside conversions using an online calculator, in order to verify the accuracy of results.
Regardless, you should know about the relevant conversion factors – for example, that 1H = 1,000 mH, 1 mH = 1,000 µH, 1 µH = 1,000 nH, and so on.
For your convenience, here is a table of common inductance units and prefixes:
| Prefix | Symbol | Factor relative to 1 H | Example conversion |
| Henry | H | 1 | 1 H = 1 H |
| Millihenry | mH | 10-3 | 1 mH = 0.001 H |
| Microhenry | µH | 10-6 | 1 µH = 0.000001H |
| Nanohenry | nH | 10-9 | 1 nH = 0.000000001 H |
| Picohenry | pH | 10-12 | 1 pH = 0.000000000001 H |
So, to use the example of converting from µH to H, we would accomplish this by multiplying by 1 x 10-6. This would mean that a 220 µH inductor works out as 220 x 10-6 = 0.00022 H.
By familiarising yourself with the relevant conversion factors and making use of a reputable online calculator for inductance unit conversion, you can help ensure you always convert these scales confidently whenever your projects as an engineer require you to do so.