Calculate milliamp hours from amp hours, or amp hours from milliamp hours. One amp hour equals 1,000 milliamp hours, plus watt hours when you add voltage.
Amp Hours to Milliamp Hours Formula
An amp hour and a milliamp hour both measure electric charge, the capacity a battery can deliver over time. A milliamp is one thousandth of an amp, so to go from amp hours to milliamp hours you multiply by 1,000:
mAh = Ah * 1000
To go the other way, from milliamp hours back to amp hours, divide by 1,000:
Ah = mAh / 1000
Where:
- Ah = charge in amp hours (ampere hours)
- mAh = charge in milliamp hours (milliampere hours)
- 1,000 = the number of milliamp hours in one amp hour
The converter has two modes. In the amp hours to milliamp hours mode you enter a value in amp hours and it multiplies by 1,000. In the milliamp hours to amp hours mode you enter a value in milliamp hours and it divides by 1,000. Turning on the advanced option lets you enter a battery voltage to also see the stored energy in watt hours, and set how many decimal places the results use.
Common Ah and mAh Battery Values
Amp hours are used to rate larger batteries such as car, solar, and UPS batteries, while milliamp hours rate smaller cells in phones, power banks, and tools. Use this table for quick reference or to check the calculator.
| Amp Hours | Milliamp Hours |
|---|---|
| 0.5 Ah | 500 mAh |
| 1 Ah | 1,000 mAh |
| 2 Ah | 2,000 mAh |
| 3.5 Ah | 3,500 mAh |
| 10 Ah | 10,000 mAh |
| 100 Ah | 100,000 mAh |
The relationship is fixed, so every amp hour value scales the same way no matter the battery chemistry or voltage.
Example Problems
Example 1: Amp hours to milliamp hours. A power tool battery is rated at 2.5 Ah and you want the value in milliamp hours. Multiply by 1,000: 2.5 x 1,000 = 2,500 mAh.
Example 2: Milliamp hours to amp hours. A power bank is labeled 20,000 mAh. Divide by 1,000: 20,000 / 1,000 = 20 Ah.
FAQ
How many milliamp hours are in an amp hour? One amp hour equals exactly 1,000 milliamp hours. The prefix milli means one thousandth, so 1 mAh is one thousandth of an amp hour.
How do you convert amp hours to milliamp hours? Multiply the number of amp hours by 1,000. For example, 4 Ah equals 4 x 1,000 = 4,000 mAh. To reverse it, divide the milliamp hours by 1,000 to get amp hours.
Does voltage change the conversion? No. Amp hours and milliamp hours both measure charge, so the conversion is always a factor of 1,000 regardless of voltage. Voltage only matters when you convert charge to energy in watt hours, which the calculator can show when you enter a voltage.
