Quick Answer: To convert mWh to mAh, divide by voltage (mAh = mWh ÷ V). To convert mAh to mWh, multiply by voltage (mWh = mAh × V).
Use our calculator below for instant conversions with voltage presets for common battery types.
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Formula: mAh = mWh ÷ Voltage
Example: 7,400 mWh ÷ 3.7V = 2,000 mAh
Common Use: Convert battery specs from energy (mWh) to charge (mAh)
Understanding the difference between mWh (milliwatt-hours) and mAh (milliamp-hours) is crucial for comparing batteries and understanding device specifications.
| Aspect | mWh (Milliwatt-Hours) | mAh (Milliamp-Hours) |
|---|---|---|
| What It Measures | Energy capacity | Charge capacity |
| Formula | mWh = mAh × Voltage | mAh = mWh ÷ Voltage |
| Depends On | Both charge AND voltage | Charge only (voltage-independent) |
| Better For Comparison | ✓ Yes - compares actual energy | Only if voltages are the same |
| Common Usage | Technical specs, energy ratings | Consumer marketing, battery labels |
| Example | 7,400 mWh (actual energy) | 2,000 mAh @ 3.7V (needs voltage) |
mWh tells you how much work the battery can do. Two batteries with the same mAh rating but different voltages have different energy capacities. Always convert to mWh (or Wh) when comparing batteries with different voltages.
Real Example:
mAh = mWh ÷ V
mWh = mAh × V
Where V is the voltage in volts
See how these calculations apply to devices you use every day:
| Battery Type | Nominal Voltage | Full Charge | Common Uses |
|---|---|---|---|
| AA/AAA Alkaline | 1.5V | 1.65V | Remote controls, toys, flashlights |
| AA/AAA NiMH Rechargeable | 1.2V | 1.4V | Cameras, gaming controllers |
| Lithium-ion (Li-ion) Single Cell | 3.7V | 4.2V | Smartphones, tablets, laptops |
| Lithium-polymer (LiPo) | 3.7V | 4.2V | Drones, RC vehicles, wearables |
| LiFePO4 (Lithium Iron Phosphate) | 3.2V | 3.65V | Solar systems, electric vehicles |
| USB Standard Output | 5V | 5V | Power banks, USB charging devices |
| Car/Automotive (Lead-Acid) | 12V | 12.6V | Vehicles, portable fridges, RVs |
| Small Solar Systems | 24V | ~28V | Off-grid solar, RV systems |
| Large Solar Systems | 48V | ~56V | Home energy storage, commercial |
| Given | Voltage | Result |
|---|---|---|
| 7,400 mWh | 3.7V | 2,000 mAh |
| 3,700 mWh | 3.7V | 1,000 mAh |
| 1,500 mWh | 1.5V | 1,000 mAh |
| 2,000 mAh | 3.7V | 7,400 mWh |
| 5,000 mAh | 5V | 25,000 mWh (25 Wh) |
Energy (mWh) = Charge (mAh) × Voltage (V)
Think of it like a water system:
A battery with higher voltage does more work with the same charge capacity. That's why you need voltage to convert between energy (mWh) and charge (mAh). They measure fundamentally different properties!
Why manufacturers use different units:
Real-world example: A 10,000 mAh power bank at 3.7V nominal voltage contains 37 Wh of energy. But when it outputs at 5V USB, conversion losses mean you'll get about 6,500-7,000 mAh delivered to your 5V device.
mWh (milliwatt-hours) measures energy capacity - the total amount of work a battery can do. mAh (milliamp-hours) measures charge capacity - the amount of electrical charge stored. The relationship is: mWh = mAh × Voltage. Energy depends on both charge AND voltage, which is why you can't compare batteries by mAh alone if they have different voltages.
No. Voltage is required because energy and charge are related through voltage (Energy = Charge × Voltage). Without knowing the voltage, mAh cannot be determined accurately. If you see a battery rated only in mWh, you must find its voltage specification to calculate mAh.
Divide milliwatt-hours by voltage: mAh = mWh ÷ V. For example, a battery with 7,400 mWh at 3.7V equals 2,000 mAh (7,400 ÷ 3.7 = 2,000). Use our calculator above for instant results.
mWh ratings appear in technical battery specifications for smaller devices like wireless earbuds, fitness trackers, smartwatches, and other wearables. It's also used in energy regulations and battery labeling in some regions. Larger batteries typically use Wh (watt-hours) instead of mWh.
Yes, as long as the voltage is correctly provided. The formula works for all battery chemistries including lithium-ion, lithium-polymer, NiMH, alkaline, and lead-acid batteries. The physics of energy = charge × voltage is universal across all battery types using standard SI units.
Multiply milliamp-hours by voltage: mWh = mAh × V. For example, 2,000 mAh at 3.7V equals 7,400 mWh (2,000 × 3.7 = 7,400). The second calculator on this page handles this conversion automatically.
Power banks show mAh based on the internal battery cells (usually 3.7V nominal). However, they output at 5V USB, so the deliverable capacity is lower due to voltage conversion. The Wh (watt-hour) rating shows true energy capacity. A 10,000 mAh @ 3.7V power bank = 37 Wh, which delivers about 7,000 mAh at 5V after conversion losses.
Nominal capacity is the rated capacity under ideal conditions (specific temperature, discharge rate). Actual capacity depends on discharge rate, temperature, battery age, and usage patterns. Real-world capacity is typically 85-95% of nominal rating. High discharge rates reduce capacity further.
Yes! 1,000 milliwatt-hours (mWh) equals 1 watt-hour (Wh). The "milli" prefix means one-thousandth, just like millimeters to meters. For larger batteries, Wh is more commonly used (e.g., laptop batteries are 50-100 Wh, not 50,000-100,000 mWh).
Yes, but car batteries are typically rated in amp-hours (Ah), not milliamp-hours. A typical car battery is 50-70 Ah @ 12V = 600-840 Wh. For mAh conversion: 50 Ah = 50,000 mAh. For mWh: 50,000 mAh × 12V = 600,000 mWh = 600 Wh.
Battery life = (Battery capacity in mAh) ÷ (Device current draw in mA). For example, a 2,000 mAh battery powering a device drawing 100 mA will last approximately 20 hours (2,000 ÷ 100 = 20). Use our battery runtime calculator for more accurate estimates accounting for efficiency losses.
Standard USB outputs 5V. USB-A typically provides 5V at 0.5-2.4A. USB-C can provide 5V, 9V, 12V, 15V, or 20V depending on Power Delivery (PD) negotiation. For basic USB calculations, use 5V. Check your device specifications for USB-C fast charging voltages.
Now that you've determined your battery capacity, it's time to see how much money you could save by going solar in your province.
Electricity rates vary dramatically across Canada—from Quebec's 7.8¢/kWh to Northwest Territories' 41¢/kWh. Your location directly impacts:
→ Check Canada's Electricity Rates by Province to calculate your potential savings and determine if solar makes financial sense in your area.
Solar Sweet Spot: Provinces with rates above 15¢/kWh typically see payback periods of 8-12 years, making solar an excellent long-term investment.
Battery capacity calculations are just one piece of the puzzle. Here's your full off-grid planning checklist:
Did You Know? In high-rate provinces like Alberta (25.8¢/kWh), Saskatchewan (19.9¢/kWh), or the territories (35-41¢/kWh), off-grid solar systems pay for themselves 40-60% faster than in low-rate provinces like Quebec or Manitoba.
Looking for more ways to plan your off-grid solar system? Check out our complete collection of calculators and planning tools: