Electric Current Converter

How to use the Electric Current Converter

Enter a current value, using a dot for decimals.

Pick the unit you have and the unit you need, for example mA to A.

Choose the significant digits.

Copy the converted current.

Electric current converter for SI and CGS units

This electric current converter changes a current between the SI ampere with its common prefixes, from nanoampere to megaampere, and the two historical CGS units, the abampere and the statampere. It is most often used for everyday prefix changes such as milliamps to amps.

Prefix conversions

Each SI step is a factor of 1000: 1 A = 1000 mA = 1,000,000 µA. The tool writes the micro prefix as uA because µ is hard to type.

20 mA   = 0.02 A
500 mA  = 0.5 A
15 A    = 15000 mA
1 uA    = 1000 nA
1 kA    = 1000 A

Typical ranges help you spot typos. Sleeping microcontrollers draw microamps, LEDs and sensors draw milliamps, household circuits carry amps, and lightning strikes reach tens of kiloamps. Industrial sensors commonly signal over a 4–20 mA current loop, which is 0.004 to 0.02 A.

Worked examples with real circuits

LED resistor. Ohm's law gives current as voltage divided by resistance. A red LED with a 2 V forward voltage on a 5 V supply with a 150 Ω resistor draws (5 − 2) ÷ 150 = 0.02 A. Convert A to mA and you get 20 mA, a typical LED rating.

Battery life. A sensor that sleeps at 50 µA on a 2000 mAh battery: convert 50 uA to mA first (0.05 mA), then divide, 2000 ÷ 0.05 = 40,000 hours, or about 4.5 years before self-discharge and wake-ups are counted. Forgetting that step is how estimates end up a factor of 1000 off.

USB power. A USB 2.0 port is specified for 500 mA and USB 3.x for 900 mA, while USB-C can offer 1.5 A or 3 A at 5 V. Check that the milliamp rating of a device fits the port before blaming the cable.

Abampere and statampere

Before SI, physicists used two versions of the centimeter-gram-second system, and each defined its own current unit:

Abampere (biot): the electromagnetic CGS unit, exactly 10 A. So 1 A = 0.1 abA.
Statampere: the electrostatic CGS unit, about 3.335640952 × 10⁻¹⁰ A. One ampere is 2,997,924,580 statamperes.

That last number is the speed of light in centimeters per second divided by ten, a reminder that the two CGS systems are linked through c. You will mostly meet these units in older physics texts and in electromagnetism written in Gaussian units.

Current is not charge or power

A battery rated in milliamp-hours (mAh) is describing charge, not current: in theory, 2000 mAh could supply 200 mA for 10 hours. To reason about run time, convert the hours with the time converter. Power is voltage times current, so 500 mA at 5 V is 2.5 W; the power converter takes it from there.

Since 2019 the ampere has been defined by fixing the elementary charge at exactly 1.602176634 × 10⁻¹⁹ coulombs, so all the SI conversions here are exact.

Frequently asked questions

How many milliamps are in an amp?

There are 1000 milliamps in one amp. So 0.02 A is 20 mA and 1500 mA is 1.5 A.

What is an abampere?

The abampere, also called the biot, is the unit of current in the electromagnetic CGS system. It is exactly 10 amperes.

Can I convert mAh to mA?

Not directly. mAh is electric charge (current multiplied by time) while mA is current. Divide the mAh rating by the current draw in mA to estimate hours of run time.

Why is the statampere so small?

It comes from the electrostatic CGS system, where charge is defined from the force between charges in centimeters and dynes. That yields a tiny unit: one ampere is about 3 × 10⁹ statamperes.