Electrical Unit Converter

About this calculator

The same capacitor is legitimately written as 0.1 µF, 100 nF or 104 depending on who drew the schematic and where they are from. Datasheets, part listings and circuit diagrams all pick different scales, and converting between them by shifting decimal points in your head is how sign errors creep in.

This converter takes a value in any unit and shows it in every other scale for that quantity at once, so you can read off whichever one you need.

How it works

SI prefixes are powers of a thousand: pico is 10⁻¹², nano 10⁻⁹, micro 10⁻⁶, milli 10⁻³, then kilo 10³, mega 10⁶ and giga 10⁹. Each step up or down is a factor of 1000, except around the base unit where milli and kilo sit.

The converter works by scaling everything to the base SI unit — ohms, farads, henries, volts, amps, watts, hertz, coulombs, joules or seconds — and then back out to every other scale. That keeps the arithmetic exact rather than chaining conversions.

A few of the conversions are not simple prefix shifts. Charge in milliamp-hours converts to coulombs by multiplying by 3.6, because a coulomb is an amp-second and an hour is 3600 seconds. Likewise a watt-hour is 3600 joules.

Watch the capitalisation. M is mega and m is milli — a factor of a billion apart. And µ is frequently typed as u because the Greek letter is awkward to enter, so 10uF means 10 µF.

p = 10⁻¹² n = 10⁻⁹ µ = 10⁻⁶ m = 10⁻³

k = 10³ M = 10⁶ G = 10⁹

1 mAh = 3.6 C coulombs are amp-seconds

1 Wh = 3600 J 1 kWh = 3.6 MJ

Worked example

A datasheet specifies a 0.047 µF capacitor, but your parts drawer is labelled in nanofarads and the board silkscreen uses 3-digit codes.

0.047 µF × 1000 = 47 nF
47 nF × 1000 = 47000 pF
As a 3-digit code: 47 followed by three zeros = 473

0.047 µF, 47 nF, 47000 pF and the marking 473 are all the same capacitor. The capacitor code decoder handles that last step directly.

Practical notes

Capacitors cause the most confusion, because all three of pF, nF and µF are in everyday use. American schematics lean toward µF, European ones toward nF.
Some older schematics use mfd or MFD for microfarads, and mmfd for picofarads. Neither is current practice, but both turn up in vintage equipment.
A bare number on a schematic usually implies the natural unit for that component — 10k beside a resistor is 10 kΩ, 100n beside a capacitor is 100 nF.
The letter can replace the decimal point to prevent it being lost in printing or photocopying: 4k7 is 4.7 kΩ, 2R2 is 2.2 Ω, 4n7 is 4.7 nF.
Milliamp-hours describe charge, not energy. Comparing two batteries by mAh alone is only valid at the same voltage — otherwise compare watt-hours.

Frequently asked questions

How many nF are in a µF?

1000. And there are 1000 pF in a nF, so a microfarad is a million picofarads. 0.1 µF, 100 nF and 100,000 pF are all the same value.

What does 4k7 mean?

4.7 kΩ. The unit letter stands in for the decimal point so it cannot be lost in a bad print or a photocopy. The same convention gives 2R2 for 2.2 Ω and 4n7 for 4.7 nF.

How do I convert mAh to watt-hours?

Multiply amp-hours by the nominal voltage. A 2000 mAh cell at 3.7 V is 2.0 × 3.7 = 7.4 Wh. Watt-hours are the fair way to compare packs of different voltages.

Is mF millifarads or microfarads?

Strictly millifarads — a thousandth of a farad, and a thousand microfarads. But older schematics sometimes used it loosely for microfarads, so check the context if the value seems implausibly large.

Why do datasheets mix µF and nF?

Regional convention, mostly. American datasheets favour microfarads even for small values (0.001 µF), European ones use nanofarads (1 nF). Both are correct; they are the same number written on different scales.