mWh to mAh (Milliwatt Hours to Milliamp Hours) Calculator

Q: How do I go from mAh to mWh?

Multiply milliamp-hours by voltage. The calculator on this page handles it for you automatically.

Convert milliwatt-hours to milliamp-hours and vice versa using voltage. Great for estimating battery charge from energy ratings in electronics.

Last updated: October 2025

Milliwatt Hours (mWh): Voltage (V):

Quick presets:

Need to Convert mAh to mWh?

Milliamp Hours (mAh): Voltage (V):

Quick presets:

📱 Real-World Device Examples

See how these calculations apply to devices you use every day:

Apple AirPods Pro (2nd Gen)
Battery: 523 mWh @ 3.7V = 141 mAh
Listening time: ~6 hours

Apple Watch Series 9
Battery: 1,280 mWh @ 3.85V = 332 mAh
Battery life: ~18 hours

Fitbit Charge 5
Battery: 180 mWh @ 3.8V = 47 mAh
Battery life: ~7 days

Portable Power Bank (Small)
Battery: 10,000 mAh @ 3.7V = 37,000 mWh (37 Wh)
Can charge iPhone 13 ~2.5 times

⚡ Common Battery Voltages Reference

Battery Type	Nominal Voltage	Common Uses
AA/AAA Alkaline	1.5V	Remote controls, toys, flashlights
AA/AAA NiMH Rechargeable	1.2V	Cameras, gaming controllers
Lithium-ion (Li-ion)	3.7V	Smartphones, tablets, laptops
Lithium-polymer (LiPo)	3.7V	Drones, RC vehicles, wearables
USB Standard	5V	Power banks, USB devices
Car/Automotive	12V	Vehicles, portable fridges
Solar Systems (Small)	24V	Off-grid solar, RV systems

Formula

mAh = mWh ÷ Volts

mWh = mAh × Volts

Understanding the Relationship

Energy (mWh) = Charge (mAh) × Voltage (V)

Think of it like water flow:

mAh (charge) = Amount of water in the tank
Voltage = Water pressure
mWh (energy) = Total work the water can do

A battery with higher voltage does more work with the same charge capacity. That's why you need voltage to convert between energy and charge.

Why manufacturers use different units:

mAh is common because it's easier to understand for consumers
mWh gives actual energy capacity, useful for comparing different voltages

Example Calculations

7400 mWh at 3.7 V = 2000 mAh
3700 mWh at 3.7 V = 1000 mAh
1500 mWh at 1.5 V = 1000 mAh
2000 mAh at 3.7 V = 7400 mWh
1000 mAh at 3.7 V = 3700 mWh

Frequently Asked Questions (FAQs)

1. Can I convert mWh to mAh without voltage?

No. Voltage is required because energy and charge are related through voltage. Without it, mAh cannot be determined accurately.

2. Where is mWh commonly used?

mWh ratings are often found in technical battery specifications for smaller devices like headphones, fitness trackers, and wearables.

3. Is this calculation accurate for all battery types?

Yes, as long as the voltage is correctly provided, the formula works for all lithium-ion or rechargeable battery types using standard SI units.

4. How do I go from mAh to mWh?

Multiply milliamp-hours by voltage. The second calculator on this page handles it for you automatically.

5. Why do power banks show mAh but energy is in Wh?

mAh is the battery cell capacity at its nominal voltage (usually 3.7V). When converted to USB output (5V), the actual deliverable capacity is lower. Always check the Wh rating for true energy capacity.

6. What's the difference between nominal and actual battery capacity?

Nominal capacity is the rated capacity under ideal conditions. Actual capacity depends on discharge rate, temperature, and battery age. Real-world capacity is typically 85-95% of nominal.

Where This Is Used

Small electronics: Earbuds, smartwatches, medical devices
Battery testing: Comparing battery capacity from energy readings
Solar-powered gadgets: Estimating charge intake or consumption rates
DIY electronics: Selecting appropriate batteries for projects
Battery replacement: Finding equivalent capacity replacements

💡 Pro Tips for Battery Selection

Tip 1: When comparing batteries, always convert to Wh (watt-hours) for accurate comparison across different voltages. A 5000mAh @ 3.7V battery (18.5Wh) has less energy than a 4000mAh @ 5V battery (20Wh).

Tip 2: For power banks, look for both mAh AND Wh ratings. The Wh rating tells you actual usable energy after voltage conversion losses.

Tip 3: Battery life depends on discharge rate. A battery may deliver less capacity at high discharge rates. Check the battery's C-rating for performance specs.

Ready to Calculate Your Solar Savings?

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:

Solar system payback period (8-25 years depending on province)
Annual savings potential ($500-$3,000+ per year)
Whether off-grid or grid-tied makes more sense

→ 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 investment.

Complete Your Off-Grid Planning

Battery capacity is just one piece of the puzzle. Here's your full off-grid planning checklist:

✓ Calculate battery capacity (you're here!)
→ Know your electricity rates – See how much you're currently paying and what you could save
→ Size your solar array – Match panel output to your energy needs
→ Calculate payback period – Determine ROI based on your province

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.

More Tools & Resources

Looking for more ways to plan your off-grid system? Check out our additional calculators and resources:

→ More Calculators