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Ah to mAh

1 Amp-hour (Ah) = 1,000 Milliamp-hour (mAh)

Result
1,000 mAh
1 Ah = 1,000 mAh

How Many Milliamp-hours in an Amp-hour?

To convert amp-hours to milliamp-hours, multiply the number of amp-hours by 1,000. The formula is mAh = Ah × 1,000. For example, 2.5 Ah equals 2,500 mAh. This conversion is useful when comparing large batteries (rated in Ah) with small device batteries (rated in mAh), or when you need to express a battery's capacity in the more granular milliamp-hour unit. It comes up frequently in solar energy systems (where battery banks are rated in Ah but charge controllers track usage in mAh), electric bicycle batteries, cordless tool batteries, and any scenario where you need to compare capacity across different battery sizes and form factors.

How to Convert Amp-hour to Milliamp-hour

  1. Start with the battery capacity in amp-hours (Ah).
  2. Multiply by 1,000 to get milliamp-hours (mAh).
  3. The result is the capacity expressed in milliamp-hours.
  4. Simply move the decimal point three places to the right.
  5. For example: 7.5 Ah → 7500. mAh → 7,500 mAh.

Real-World Examples

Car battery — A 65 Ah automotive battery
65 × 1,000 = 65,000 mAh. This is roughly 16 times the capacity of a 4,000 mAh smartphone battery (though at 12V vs 3.7V, the energy difference is much larger).
Cordless drill battery — A 2.0 Ah 20V battery pack
2.0 × 1,000 = 2,000 mAh. A "5.0 Ah" premium pack is 5,000 mAh — 2.5 times the run time of the standard pack.
E-bike battery — A 14 Ah, 36V lithium battery
14 × 1,000 = 14,000 mAh. At 36V, this stores 14 × 36 = 504 Wh of energy — enough for 20-50 miles of assisted cycling.
Solar battery bank — A 100 Ah deep-cycle battery
100 × 1,000 = 100,000 mAh. At 12V, this stores 1,200 Wh (1.2 kWh) of energy — enough to run a few lights and a phone charger overnight.

Quick Reference

Amp-hour (Ah) Milliamp-hour (mAh)
1 1,000
2 2,000
5 5,000
10 10,000
25 25,000
50 50,000
100 100,000
500 500,000
1,000 1,000,000

History of Amp-hour and Milliamp-hour

The amp-hour has been used since the earliest days of rechargeable batteries. Gaston Planté invented the lead-acid battery in 1859, and engineers quickly needed a way to express how long a fully charged battery could deliver current before being depleted. The amp-hour emerged as the natural choice: a battery that could supply 1 amp for 10 hours had a "10 amp-hour" capacity. As batteries became central to portable electronics in the late 20th century, the milliamp-hour became the consumer-facing unit. Nokia's iconic 3310 (2000) had a 1,000 mAh battery; today's flagship smartphones carry 4,000-6,000 mAh. The explosion of portable devices — smartphones, tablets, wireless earbuds, smartwatches, fitness trackers — made mAh a household term that even non-technical consumers recognize and compare when shopping. The increasing electrification of transportation has brought the amp-hour full circle. Electric vehicle batteries are rated in kWh for total energy, but individual cells are specified in Ah. A Tesla Model 3 battery pack, for instance, uses cells rated at approximately 4.8 Ah each, assembled into modules and packs to achieve 50-82 kWh of total storage.

Common Mistakes to Avoid

  • Dividing instead of multiplying. To go from Ah to mAh, multiply by 1,000 — the number gets larger. A 5 Ah battery is 5,000 mAh, not 0.005 mAh.
  • Directly comparing mAh across different voltages. A 100 Ah 12V car battery stores 1,200 Wh, while a 100,000 mAh (100 Ah) 3.7V power bank stores only 370 Wh. Same mAh, vastly different energy. Always consider voltage when comparing batteries of different types.

Frequently Asked Questions

How many milliamp-hours is 1 amp-hour?
One amp-hour equals exactly 1,000 milliamp-hours. This is a simple metric prefix conversion where "milli" means one-thousandth.
How long will a 100 Ah battery last?
It depends entirely on the load. A 100 Ah battery supplying 10 A will last about 10 hours. Supplying 1 A, it lasts about 100 hours. Supplying 100 A, about 45-50 minutes (less than 1 hour because high discharge rates reduce effective capacity). The formula is: hours ≈ Ah ÷ amps of draw.
Why is my cordless tool battery rated in Ah instead of mAh?
Cordless tool batteries typically range from 1.5 to 12 Ah — values that are more readable in amp-hours than in milliamp-hours (1,500 to 12,000 mAh). Additionally, the Ah convention aligns with the higher-power industrial and automotive battery markets, reinforcing the perception of robust performance.
Quick Tip

When comparing cordless tool battery packs, remember that Ah alone does not tell the whole story. A 5.0 Ah pack at 20V stores 100 Wh, while a 5.0 Ah pack at 40V stores 200 Wh — double the energy. Higher voltage also means more power for demanding tools. Check both the Ah rating and the voltage to understand true battery capability. Some manufacturers use "Wh" on the label, which combines both factors and gives the most accurate comparison.