kWh to mAh Calculator
This calculator converts kilowatt-hours (kWh) into milliamp-hours (mAh), using voltage. It's useful when converting large energy usage values into small-scale battery capacities, such as estimating how many phone battery charges fit into 1 kWh.
What is kWh to mAh Conversion?
The conversion from kilowatt-hours (kWh) to milliamp-hours (mAh) helps you translate large energy usage values into small battery capacities. While kilowatt-hours are commonly used to measure household or industrial energy consumption, milliamp-hours are typically used for small battery-powered electronics like smartphones, tablets, or flashlights.
Understanding this conversion is useful in contexts such as:
- Estimating how many phone batteries can be charged with 1 kWh of energy
- Calculating power bank capacities from a known energy source
- Understanding electric consumption down to the portable battery scale
Formula for Conversion
To convert kWh to mAh, you can use the following formula:
mAh = (kWh × 1,000,000) / Voltage
Why 1,000,000? Because:
- 1 kilowatt = 1000 watts
- 1 hour = 3600 seconds
- 1 Ah = 1000 mAh
- So: 1 kWh = 1000 Wh = (1000 Wh × 1000) / V = mAh
Example:
Convert 1 kWh into mAh at 3.7V (typical smartphone battery voltage):
mAh = (1 × 1,000,000) / 3.7 = 270,270 mAh
Why Convert kWh to mAh?
- Consumer Electronics Planning: Manufacturers or hobbyists can estimate how much energy reserve in the grid or backup systems will translate to battery charges.
- Solar System Design: Knowing how much solar power (in kWh) can be stored in lithium batteries (in mAh) helps with energy system sizing.
- Marketing & Product Comparison: Some brands advertise batteries in Wh or kWh; others use mAh. Converting between them allows for fair comparison.
- UPS and Power Banks: If your system provides energy in kWh (e.g. grid power or a generator), this conversion helps you match storage needs in mobile mAh-based batteries.
Real-World Examples
- Example 1: Grid to smartphone
A household uses 10 kWh per day. How many iPhones can you charge per day if each charge is about 12Wh (3250 mAh @ 3.7V)?
10,000Wh ÷ 12Wh = 833 full charges! - Example 2: Powering a 10,000mAh USB battery from 0.5 kWh
0.5 × 1,000,000 = 500,000 mWh
Assuming 3.7V lithium cells: mAh = 500,000 / 3.7 = ~135,135 mAh
So you could charge that 10,000mAh power bank about 13 times. - Example 3: Laptop battery comparison
A 14.8V, 4400mAh laptop battery = 14.8 × 4.4 = 65Wh
That means a 1 kWh solar generator could charge this battery 15+ times.
Voltage: The Key Variable
Voltage plays a critical role in conversion accuracy. A battery storing 10,000mAh at 3.7V stores far less energy than a 10,000mAh battery at 12V.
Here’s a comparison of 10,000mAh batteries at different voltages:
- 3.7V → 37 Wh
- 5V → 50 Wh
- 12V → 120 Wh
- 24V → 240 Wh
Thus, when converting from kWh to mAh, always match the target battery's voltage correctly. Using the wrong voltage may result in massive under- or over-estimation.
Common Voltage Reference Table
| Device | Typical Voltage |
|---|---|
| Smartphone battery | 3.6–3.8 V |
| USB power banks | 3.7 V (internal), 5V output |
| Laptop battery | 10.8–14.8 V |
| Lead-acid UPS battery | 12 V |
| Electric scooter / e-bike | 24 V / 36 V / 48 V |
Frequently Asked Questions (FAQ)
What is the purpose of converting kWh to mAh?
It allows you to relate large energy measurements (like grid usage) to small battery capacities (like phones, flashlights). It helps with capacity planning, marketing comparisons, and system design.
Is this conversion accurate for all batteries?
Mathematically yes, but in practice you must account for energy losses, efficiency, battery degradation, and charge limits. The mAh figure tells you theoretical capacity—not necessarily what’s usable.
How do I convert Wh directly to mAh?
Use this simplified formula:
mAh = (Wh × 1000) / V
It’s the same idea, but using Wh instead of kWh.
Is there a reverse calculator?
Yes. You can reverse the formula to calculate:
kWh = (mAh × V) / 1,000,000
How much energy is 1 million mAh?
At 3.7V: (1,000,000 mAh × 3.7V) / 1,000,000 = 3.7 kWh. That’s enough to power a 100W device for 37 hours.
Conclusion
Converting kilowatt-hours to milliamp-hours bridges the gap between large-scale energy and small-scale device capacity. Whether you're comparing backup energy storage, sizing solar battery banks, or simply curious how much mobile battery you get from household energy, this calculator provides an intuitive and reliable way to understand that relationship. Always include the correct voltage and efficiency factor for best results, and use this tool as a baseline for smarter energy planning.