What Does mAh Actually Mean?
mAh stands for milliamp-hour — a unit of electrical charge that describes how much energy a battery stores. A battery rated at 2000 mAh can theoretically deliver 2000 milliamps of current for one hour, or 1000 milliamps for two hours, or 100 milliamps for twenty hours. Higher mAh generally means longer runtime in the same device, but it isn’t the whole story.
Capacity ratings are measured under specific test conditions (a fixed discharge rate, temperature, and cut-off voltage), so the mAh printed on a battery is a benchmark figure, not a guarantee. Two batteries with identical mAh ratings can perform very differently in a high-drain device like a digital camera versus a low-drain device like a remote control, because capacity fades faster under heavy current draw — a behaviour called the Peukert effect. This is also why NiMH batteries with higher on-paper mAh don’t always outlast lithium cells with lower on-paper mAh: voltage stability under load matters as much as the number itself.
Key takeaway: mAh predicts relative runtime within the same chemistry and device type far more reliably than it predicts runtime across chemistries.
Battery Capacity by Size — Full Comparison Chart
| Battery Size | Alkaline (mAh) | Lithium Primary (mAh) | NiMH Rechargeable (mAh) | Nominal Voltage |
|---|---|---|---|---|
| AAA | ~1,000–1,200 | ~1,200 | 600–1,000 | 1.5V (1.2V NiMH) |
| AA | ~1,800–2,700 | ~3,000 | 1,900–2,700 | 1.5V (1.2V NiMH) |
| C | 6,000–8,000 | — | 4,000–6,000 | 1.5V (1.2V NiMH) |
| D | 12,000–18,000 | — | 2,200–12,000 | 1.5V (1.2V NiMH) |
| 9V | 400–600 | 600–1,200 | 200–400 (per charge) | 9V |
| CR2032 (coin cell) | — | 225–240 | 65–90 (rechargeable variants) | 3V |
| 18650 (Li-ion) | — | 2,000–3,500 | — | 3.6–3.7V |
Figures are typical ranges across quality brands and vary by manufacturer, drain rate, and temperature. See our dedicated size guides — AA, AAA, C, D, 9V, CR2032, and 18650 — for full breakdowns of each format.
Uniross Batteries by Chemistry and Capacity
Once you know which capacity range fits your device, here’s where to find it:
- Alkaline Essentials — standard-capacity alkaline for everyday, low-drain devices
- Alkaline Power Plus — mid-tier capacity for regular household use
- Alkaline Max Power — highest-capacity alkaline line for high-drain devices
- Extra Heavy Duty — budget zinc-chloride option for minimal-drain devices
- Lithium Ultra (AA, AAA, 9V) — highest mAh-per-gram, best for high-drain and cold-weather use
- NiMH Rechargeable Batteries — AA/AAA rechargeables for frequently-used, high-drain devices
- Lithium Rechargeable (18650 / RCR123A) — Li-ion cylindrical cells for flashlights, headlamps, and power tools
- Lithium USB-C Rechargeable — built-in USB-C charging, no separate charger required
- Lithium Coin Cell Batteries (CR2032 and more) — CR2032, CR2025, CR2016, and other coin cell sizes
- Alkaline Coin Cell Batteries — lower-cost alkaline button cells for low-drain electronics
- Battery Chargers — chargers matched to NiMH and Li-ion capacity and cycle life
Why Rechargeable (NiMH) mAh Numbers Can Be Misleading
NiMH batteries are often marketed with mAh ratings that look competitive with, or even higher than, alkaline equivalents. In practice, NiMH runs at a nominal 1.2V rather than 1.5V, and that lower, gradually-declining voltage means real-world runtime in voltage-sensitive devices is usually shorter than the raw mAh figure suggests. NiMH still wins on total cost of ownership across hundreds of recharge cycles — it just isn’t a direct mAh-for-mAh swap with alkaline. See the NiMH Rechargeable Batteries range, and for a full breakdown of how the two behave side by side, see our Lithium 1.5V vs NiMH 1.2V comparison.
Why Lithium Primary Cells Outperform Their mAh Rating
Lithium primary batteries (non-rechargeable, 1.5V lithium AA/AAA or 3V coin cells) hold their voltage flat for most of the discharge curve, then drop sharply near the end. This means a lithium cell delivers close to its full rated capacity at usable voltage, whereas alkaline cells decline gradually throughout discharge — so two batteries with the same mAh rating won’t necessarily power a device for the same length of time. Lithium’s flat discharge curve is also why it performs far better in cold conditions and high-drain electronics, covered in our Alkaline Battery Performance Guide. See the Lithium Ultra AA/AAA/9V range or Lithium Coin Cell Batteries.
How to Read a Capacity Rating Before Buying
- Match capacity to drain, not just device type. A high-mAh alkaline battery in a high-drain device (camera flash, gaming controller) will still underperform a lower-mAh lithium cell built for that load.
- Compare within the same chemistry. mAh comparisons are only meaningful between batteries of the same chemistry and voltage — comparing alkaline mAh to NiMH mAh directly will mislead you.
- Check the cut-off voltage the rating was tested at. A capacity figure tested to a 0.9V cut-off will look larger than one tested to 1.0V, even from the same cell.
- For rechargeables, factor in cycle count. A 2,000 mAh NiMH battery used 500 times delivers far more total energy over its life than a single-use alkaline cell of higher mAh.
Quick Reference: Which Capacity Do You Need?
| Use Case | Recommended Capacity Range | Best Chemistry |
|---|---|---|
| TV remotes, clocks, wall lights | Standard capacity (no need for high mAh) | Alkaline |
| Digital cameras, flash units | High mAh, high-drain rated | Lithium primary or NiMH |
| Smoke detectors, security sensors | Long shelf life over peak capacity | Alkaline or Lithium (9V/CR2032) |
| Flashlights, headlamps, power tools | High mAh, high discharge rate | Lithium-ion (18650) |
| Gaming controllers, wireless mice | High-cycle-life mAh retention | NiMH rechargeable |
| Key fobs, motherboards, medical devices | Stable low-drain capacity | CR2032 lithium coin cell |
Frequently Asked Questions
Is higher mAh always better?
Not necessarily. Higher mAh means more stored energy, but real-world runtime also depends on the device’s drain rate, the battery’s voltage stability under load, and temperature. A lower-mAh lithium battery can outlast a higher-mAh alkaline battery in a high-drain device.
Why do NiMH batteries have lower mAh than alkaline of the same size?
NiMH cells run at 1.2V instead of 1.5V, so manufacturers rate them differently. Despite a lower headline number in some sizes, NiMH remains cost-effective over hundreds of recharge cycles.
Does mAh affect shelf life?
No — mAh measures stored energy capacity, not how long a battery can sit unused before losing charge. Shelf life is a separate spec (alkaline typically 5–10 years; lithium primary 10+ years).
What’s the mAh of a standard AA battery?
Alkaline AA batteries typically range from 1,800–2,700 mAh, lithium AA around 3,000 mAh, and NiMH rechargeable AA from 1,900–2,700 mAh, depending on the brand and grade.
Can I use a higher mAh battery than my device requires?
Yes, as long as the voltage and size match. A higher-mAh battery of the correct voltage and size will simply last longer — it won’t damage the device.
