Convert mAh to Ah
Use this mAh to Ah Calculator to convert battery capacity in milliamp-hours into amp-hours instantly. Milliamp-hours and amp-hours both measure the same thing — electric charge stored in a battery — but on different scales. Milliamp-hours are used for smaller batteries like phone cells, power banks, laptop batteries, RC battery packs, and single lithium cells. Amp-hours are used for larger batteries like car batteries, solar storage systems, RV battery banks, and marine power systems.
The conversion is simple: Ah = mAh ÷ 1000. One amp-hour equals exactly 1000 milliamp-hours. A 5000 mAh phone battery is 5.0 Ah. A 20000 mAh power bank is 20.0 Ah. A 100Ah solar storage battery is 100,000 mAh. Both units describe the same capacity, just at different scales. Converting between them helps you compare batteries, use calculators designed for Ah inputs, and understand manufacturer datasheets.
mAh to Ah Calculator
Why Use Our mAh to Ah Calculator
Use Ah-Based Battery Calculators
Many battery tools — including runtime calculators, charge time calculators, and Ah to kWh converters — require input in amp-hours. If your battery is rated in mAh, this calculator converts the value so you can use it directly in those tools without manual arithmetic.
Compare Phone and Power Bank Capacities
Phone batteries and power banks are almost always rated in mAh. Converting mAh to Ah gives a cleaner number for comparing capacity across different battery types and understanding how much energy a device actually stores.
Understand Battery Datasheets
Battery datasheets and BMS specifications often mix mAh and Ah depending on the battery size. Converting between units helps you read and interpret technical documents accurately without confusion over the scale of numbers.
Size Charge Controllers and Chargers
Solar charge controllers, battery chargers, and BMS devices are usually configured in amps and amp-hours. If your battery capacity is given in mAh, converting to Ah first lets you correctly calculate the required charge current and set appropriate limits.
Plan Battery Banks from Individual Cells
Individual lithium cells are typically rated in mAh — for example, a 18650 cell rated at 3500 mAh is 3.5 Ah. When building a battery pack from individual cells, converting mAh to Ah and then calculating series and parallel arrangements is a standard part of the design process.
Avoid Unit Confusion in Energy Calculations
Mixing mAh and Ah in calculations leads to errors. A common mistake is entering mAh values into a formula expecting Ah, resulting in a 1000x error in the final result. Using this converter first ensures your inputs match the unit the formula requires.
mAh to Ah Conversion Formula
The formula for converting milliamp-hours to amp-hours is straightforward:
Ah = mAh ÷ 1000
And the reverse — converting amp-hours back to milliamp-hours — is:
mAh = Ah × 1000
The factor of 1000 comes from the metric prefix "milli," which always means one-thousandth. Just as 1 kilogram equals 1000 grams, 1 amp-hour equals 1000 milliamp-hours. The conversion does not depend on voltage, temperature, battery chemistry, or any other variable. It is a pure unit conversion.
For example, a 4500 mAh smartphone battery converts to 4500 ÷ 1000 = 4.5 Ah. A 280Ah LiFePO4 cell converts to 280 × 1000 = 280,000 mAh. Whether you are working with a tiny hearing aid battery or a large solar storage bank, the same formula applies every time.
mAh to Ah Quick Reference Table
The table below shows common mAh values converted to Ah. These figures are exact and based on the formula Ah = mAh ÷ 1000.
| Milliamp-Hours (mAh) | Amp-Hours (Ah) | Typical Application |
|---|---|---|
| 500 mAh | 0.5 Ah | Small wearable / IoT battery |
| 1000 mAh | 1.0 Ah | Earbuds charging case / small RC battery |
| 2000 mAh | 2.0 Ah | Basic smartphone / small power bank |
| 2500 mAh | 2.5 Ah | Mid-range phone battery |
| 3000 mAh | 3.0 Ah | Standard smartphone battery |
| 3500 mAh | 3.5 Ah | 18650 Li-ion cell (high capacity) |
| 4000 mAh | 4.0 Ah | Large phone battery |
| 5000 mAh | 5.0 Ah | Large phone / small power bank |
| 10000 mAh | 10.0 Ah | Medium power bank |
| 20000 mAh | 20.0 Ah | Large power bank |
| 30000 mAh | 30.0 Ah | Extra large power bank |
| 50000 mAh | 50.0 Ah | High capacity portable power station |
| 100000 mAh | 100.0 Ah | 100Ah lithium battery |
| 200000 mAh | 200.0 Ah | 200Ah solar storage battery |
| 280000 mAh | 280.0 Ah | 280Ah LiFePO4 prismatic cell |
Understanding mAh and Ah
Milliamp-hours and amp-hours are both measures of electric charge, not energy. They describe how much current a battery can deliver over time. A battery rated at 3000 mAh (3.0 Ah) can theoretically deliver 3000 milliamps for one hour, 1500 milliamps for two hours, 300 milliamps for ten hours, or any other combination of current and time that multiplies to 3000 mAh under ideal conditions.
Neither mAh nor Ah tells you the total energy stored unless voltage is also known. Energy in watt-hours equals capacity in amp-hours multiplied by voltage. A 5000 mAh phone battery at 3.7V stores about 5.0 × 3.7 = 18.5 Wh of energy. A 100Ah solar battery at 48V stores 100 × 48 = 4800 Wh or 4.8 kWh. The mAh or Ah number alone, without voltage, only tells you charge capacity — not usable energy.
In everyday use, mAh is widely used for consumer electronics because the numbers are more intuitive at that scale. Writing 5000 mAh is clearer than writing 0.005 Ah for a phone battery. For larger batteries, the Ah scale is more practical — writing 100 Ah is easier to work with than writing 100,000 mAh. Both are correct representations of the same physical quantity, just using different metric scales.
mAh to Ah Conversion Examples
Example 1: Smartphone Battery — 4500 mAh
A smartphone battery rated at 4500 mAh converts to 4500 ÷ 1000 = 4.5 Ah. If this phone battery has a nominal voltage of 3.85V, the stored energy is 4.5 × 3.85 = 17.3 Wh. This is the energy unit used by power banks to show charging capacity for devices.
Example 2: Power Bank — 20000 mAh
A 20000 mAh power bank converts to 20000 ÷ 1000 = 20.0 Ah. At a typical internal cell voltage of 3.7V, the stored energy is 20.0 × 3.7 = 74 Wh. Note that actual charging output is lower due to USB conversion losses, which is why power bank capacity in Wh is often lower than the mAh label implies.
Example 3: 18650 Lithium Cell — 3500 mAh
A high-capacity 18650 Li-ion cell rated at 3500 mAh is the same as 3.5 Ah. At a nominal voltage of 3.6V, this cell stores 3.5 × 3.6 = 12.6 Wh. Battery packs built from multiple 18650 cells add Ah in parallel and voltage in series, with the total pack capacity calculated from the combined Ah and system voltage.
Example 4: RC LiPo Pack — 6000 mAh
A 6000 mAh 3S LiPo pack for RC vehicles converts to 6.0 Ah. With a 3S nominal voltage of 11.1V, the pack stores 6.0 × 11.1 = 66.6 Wh of energy. The mAh and Ah values are used to calculate run time and C rate requirements for the vehicle's motor and ESC.
mAh vs Ah — Key Differences
The only difference between mAh and Ah is the unit scale. Milliamp-hours are 1/1000th of an amp-hour. There is no technical or physical difference in what they measure. A 3000 mAh battery and a 3.0 Ah battery are identical in capacity. The choice of unit is simply a matter of convention based on battery size.
Small batteries — phone cells, earbuds, cameras, RC packs — are almost always described in mAh because this gives whole numbers that are easier to compare. A 4000 mAh phone battery is simpler to understand than a 4.0 Ah phone battery, even though both are correct. Large batteries — automotive, solar, marine, EV — are described in Ah because 100 Ah is cleaner than 100,000 mAh.
When working with both types in the same calculation — for example, counting how many phone recharges a solar battery can provide — you must convert to the same unit first. Use Ah = mAh ÷ 1000 to bring small battery values up to the Ah scale, or mAh = Ah × 1000 to bring large battery values down to the mAh scale, before doing any arithmetic.
Power Bank Ratings and mAh Accuracy
Power bank manufacturers rate capacity at the cell voltage, typically 3.6V to 3.7V, but USB output is at 5V. This step-up conversion is not 100% efficient. A 10000 mAh power bank stores energy at ~3.7V but delivers it at 5V, so the actual usable charge delivered to a device is less than 10000 mAh at 5V. Efficiency is typically 80% to 90%, meaning a 10000 mAh power bank may effectively charge a phone with around 7000 to 8500 mAh of actual current at 5V.
This is why comparing power bank capacity in Wh is more meaningful than mAh alone. Wh = mAh × V ÷ 1000. A 10000 mAh power bank at 3.7V cell voltage stores 37 Wh. Dividing by 5V output gives 7400 mAh of effective charge at 5V before efficiency losses. This calculation explains why advertised mAh capacity and actual device charging performance often differ.
When choosing a power bank for travel, multiply the rated mAh by the cell voltage and divide by the device charging voltage to estimate real charging performance. This conversion starts with an mAh to Ah step, followed by a Wh calculation, then a final conversion at the output voltage.
Using mAh and Ah in Battery System Design
In battery system design, the Ah unit is standard for sizing solar charge controllers, BMS devices, inverters, and fusing. When a system uses small cells rated in mAh, the first step is always to convert cell capacity to Ah, then calculate total pack capacity based on the series and parallel configuration. For example, four 18650 cells at 3500 mAh each in parallel give a combined 14000 mAh or 14.0 Ah at the cell voltage.
After converting to Ah, the remaining battery design steps use Ah throughout. Charge current in amps is calculated from the C rate and Ah. Runtime is calculated by dividing Ah by the load current. Energy in kWh is calculated by multiplying Ah by pack voltage and dividing by 1000. Starting from mAh and making the conversion to Ah early in the calculation avoids scale errors in every subsequent step.
For solar battery banks and off-grid systems, all calculations are done in Ah and kWh. The solar panel output is measured in amp-hours per day or watt-hours per day. The battery capacity is sized in Ah. The inverter is sized in kW. mAh values from individual cells need to be converted to Ah before they can be used in any of these sizing formulas correctly.
Common Mistakes to Avoid
- Forgetting to divide by 1000 when converting: Entering 5000 mAh into a formula that expects Ah gives a 1000x error in the result. Always convert mAh to Ah before using Ah-based formulas.
- Assuming mAh equals energy: mAh measures charge, not energy. You need both mAh and voltage to calculate energy in Wh or kWh. A 5000 mAh battery at 3.7V stores different energy than a 5000 mAh battery at 7.4V.
- Comparing power banks by mAh without considering voltage: Power banks rated at the same mAh but different internal cell voltages do not store the same energy. Use Wh for accurate energy comparison between power banks.
- Mixing mAh and Ah in the same calculation: Adding 5000 mAh and 5.0 Ah as if they are the same scale produces a wrong result. Convert to the same unit before doing arithmetic.
- Confusing mAh with mA: Milliamp-hours (mAh) is a capacity unit. Milliamps (mA) is a current unit. These are not the same thing and are used in different places in battery calculations.
- Using mAh-rated cell values without adjusting for pack voltage: When building multi-cell packs, mAh stays the same in parallel connections but voltage adds in series. Always account for total pack voltage and Ah together when calculating energy.
Related Tools
Use these related calculators to continue your battery planning and conversion workflow:
- mAh to Wh Calculator
- Wh to mAh Calculator
- Ah to kWh Calculator
- Battery Capacity Calculator
- Battery Runtime Calculator
- Charge Time Calculator