What is an amperes to milliamperes converter?
An amperes to milliamperes converter is an online tool that translates an electric current expressed in amperes (A) into its equivalent value in milliamperes (mA), and back again. Both units measure the same physical quantity, current, which describes the rate at which electric charge flows through a conductor. The only difference between them is scale: the milliampere is simply a smaller, sub-multiple version of the ampere. This makes the converter useful whenever you need to move between the large currents quoted on circuit breakers or appliances and the small currents quoted on electronic components, sensors, or batteries.
How it works
The ampere is the base unit of electric current in the International System of Units (SI). The prefix “milli-” means one thousandth, so one milliampere is one thousandth of an ampere. Because the relationship is a fixed power of ten, conversion is a simple matter of multiplying or dividing by 1,000.
To go from amperes to milliamperes you multiply by 1,000, because there are 1,000 milliamperes in every ampere. To go the other way, from milliamperes to amperes, you divide by 1,000. There is no rounding or approximation involved: the factor of 1,000 is exact by definition.
Formula for conversion
To convert amperes to milliamperes, multiply the current in amperes by 1,000:
To convert milliamperes to amperes, divide the current in milliamperes by 1,000:
Amperes to milliamperes conversion table
The table below lists common current values in amperes alongside their equivalents in milliamperes:
| Amperes (A) | Milliamperes (mA) |
|---|---|
| 0.001 | 1 |
| 0.01 | 10 |
| 0.1 | 100 |
| 0.5 | 500 |
| 1 | 1,000 |
| 2 | 2,000 |
| 2.5 | 2,500 |
| 5 | 5,000 |
| 10 | 10,000 |
| 100 | 100,000 |
Examples of conversion
Example 1: 1 ampere to milliamperes
A USB charger is rated to deliver 1 A. To express this in milliamperes, multiply by 1,000:
So 1 ampere equals 1,000 milliamperes.
Example 2: 2,500 milliamperes to amperes
A power bank lists a maximum output of 2,500 mA. To find this in amperes, divide by 1,000:
So 2,500 milliamperes equals 2.5 amperes.
Example 3: Zero current
If no current flows, the value is the same in either unit. Converting 0 A gives:
Zero amperes is simply zero milliamperes.
Notes
- The conversion factor of 1,000 is exact, so results are never approximations.
- Milliamperes are most often used for small currents in electronics, such as LED drive currents (typically 10-20 mA) or microcontroller pins.
- Amperes are used for larger loads such as household appliances, motors, and circuit breakers.
- Be careful not to confuse current (measured in amperes) with capacity (often measured in milliampere-hours, mAh) or with power (measured in watts).
Frequently asked questions
How many milliamperes are in 1 ampere?
There are exactly 1,000 milliamperes in 1 ampere, because the prefix “milli-” denotes one thousandth.
How do I convert milliamperes to amperes?
Divide the number of milliamperes by 1,000. For example, 500 mA divided by 1,000 equals 0.5 A.
Why are small currents measured in milliamperes?
Many electronic components carry very small currents. Expressing them in milliamperes avoids long strings of leading zeros, so 0.02 A is written more conveniently as 20 mA.
Is the conversion between amperes and milliamperes exact?
Yes. Both units measure the same quantity and are linked by the fixed factor of 1,000, so no rounding error is introduced by the conversion itself.
What is the difference between milliamperes (mA) and milliampere-hours (mAh)?
Milliamperes measure the rate of current flow at a given instant, while milliampere-hours measure electric charge, that is, current delivered over time. A battery rated at 2,500 mAh can supply 2,500 mA for one hour, or 1,250 mA for two hours.
How do I convert amperes to microamperes instead?
Microamperes are one millionth of an ampere, so multiply amperes by 1,000,000. Equivalently, multiply milliamperes by 1,000 to reach microamperes.