Power Bank mAh, Wh & Rated Capacity Reference
Quick answer: nominal cell mAh, stored energy in Wh and rated output capacity are different measurements. Convert mAh and nominal voltage to Wh first, then compare rated output using the same output voltage and test basis.
Power Bank mAh to Wh Calculator
Enter nominal cell capacity and nominal voltage. The calculator returns nominal stored energy in watt-hours.
38.50 Wh
Formula: Wh = mAh × V ÷ 1000. This is nominal stored energy, not guaranteed USB output energy.
Nominal Capacity (mAh)
Charge quantity at the stated nominal cell voltage. Example: 10,000mAh at 3.85V.
Charge quantity at the stated nominal cell voltage. Example: 10,000mAh at 3.85V.
Nominal Energy (Wh)
Stored energy on a common basis. Example: 10,000mAh × 3.85V ÷ 1000 = 38.5Wh.
Stored energy on a common basis. Example: 10,000mAh × 3.85V ÷ 1000 = 38.5Wh.
Rated Output Capacity
Output-side capacity under a stated USB voltage and test condition; it is lower because conversion losses occur.
Output-side capacity under a stated USB voltage and test condition; it is lower because conversion losses occur.
Quick Buyer Check
Use the same basis before comparing supplier capacity claims.
Nominal mAh
Confirm both nominal capacity and nominal voltage, then convert to Wh.
Confirm both nominal capacity and nominal voltage, then convert to Wh.
Wh
Check that Wh matches mAh × nominal voltage for the exact SKU.
Check that Wh matches mAh × nominal voltage for the exact SKU.
Rated Output
Compare only when output voltage and test condition are stated.
Compare only when output voltage and test condition are stated.
Test Basis
Load, cable, temperature and sample revision can change measured output.
Load, cable, temperature and sample revision can change measured output.
Examples & Related Engineering
F82-D · 10,000mAh / 3.85V / 38.5Wh
10,000mAh × 3.85V ÷ 1000 = 38.5Wh.
G102 Max · 71.62Wh / 45W
Wh describes stored battery energy; W describes output power. Evaluate both separately.
Continue the Engineering Review
Cell & PACK Selection →
PD & PPS Charging →
Thermal & DC-DC Efficiency →
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Power Bank Capacity FAQ
How do I convert power bank mAh to Wh?
Multiply nominal capacity in mAh by nominal voltage, then divide by 1000. Example: 10,000mAh × 3.85V ÷ 1000 = 38.5Wh.
Why is rated output capacity lower than nominal mAh?
The battery stores energy at cell voltage while USB output is delivered at a regulated output voltage. DC-DC, PCB, cable and thermal losses reduce usable output.
Should I compare power banks by mAh or Wh?
Use Wh to compare stored energy, especially when nominal voltages differ. Review rated output and test conditions separately.
Can I use a fixed 80% efficiency for rated capacity?
Only for early estimation. Production claims should use measured data because efficiency changes with design, load, voltage, cable and thermal conditions.
What should a buyer ask the supplier to provide?
Ask for nominal capacity, nominal voltage, Wh, cell/PACK identity, rated output or output-energy test data where applicable, test conditions and exact SKU/revision confirmation.