Ah to 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. The extra zeros do not change the stored energy; they only restate the same charge capacity in a smaller unit. That is why voltage still matters. A 5 Ah tool battery and a 5 Ah phone-scale battery are both 5,000 mAh, but if they operate at different voltages, they store very different watt-hour totals and deliver very different real-world run times. The conversion also helps when product packaging, airline limits, and gadget reviews switch back and forth between Ah-style and mAh-style labeling.

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

Related Converters

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.
• Assuming a higher mAh number means a battery can deliver more current at once. Capacity and maximum discharge rate are different specifications.
• Forgetting that marketed battery labels are sometimes rounded. A pack sold as 5 Ah may contain cells whose nominal combined rating is slightly below or above 5,000 mAh.

Frequently Asked Questions

Further Reading