Ampere Hour to Watt Hour Calculator
Convert amp-hours (Ah) to watt-hours (Wh) or kilowatt-hours (kWh) with voltage—instant bidirectional Ah ↔ Wh ↔ kWh (also mAh). Searches for ah to kwh land here: kWh = Ah × V ÷ 1000. Not a runtime or UPS Ah sizing tool.
Calculator
Quick: Ah + V → Wh. Advanced: Wh → Ah, mAh, or kWh units.
About this calculator
This ampere hour to watt hour calculator converts charge (Ah) to energy (Wh) with Wh = Ah × V. It does not estimate runtime hours or UPS backup minutes. For DC pack hours use battery runtime; for UPS Ah procurement use UPS battery sizing. Browse the power calculator hub.
Calculation Results
≈ 1200 Wh (1.200 kWh)
100 Ah × 12 V
Formula: Wh = Ah × V
Uses nominal voltage. Real usable Wh depends on DoD, temperature, and discharge rate—screen only.
Ah to Wh quick reference (common voltages)
Wh = Ah × V · kWh = Wh ÷ 1000 · Ah = mAh ÷ 1000. Click a row to load the calculator.
| Capacity | Voltage | Energy |
|---|---|---|
| 12 V | 1200 Wh (1.2 kWh) | |
| 24 V | 2400 Wh (2.4 kWh) | |
| 48 V | 4800 Wh (4.8 kWh) | |
| 12 V | 1440 Wh (1.44 kWh) | |
| 12 V | 2400 Wh (2.4 kWh) | |
| 3.7 V | 7.4 Wh | |
| 12 V | 100 Ah | |
| 12 V | ≈ 16.7 Ah | |
| 12 V | ≈ 41.7 Ah | |
| 12 V | 3768 Wh (3.768 kWh) | |
| 48 V | 15072 Wh (15.07 kWh) |
mAh ↔ Ah and Ah ↔ kWh
- Ah = mAh ÷ 1000 (2000 mAh = 2 Ah). mAh = Ah × 1000.
- kWh = (Ah × V) ÷ 1000. Example: 100 Ah × 12 V = 1.2 kWh.
- Ah = (kWh × 1000) ÷ V. Use Wh→Ah mode with the kWh unit selected.
Ampere hour to watt hour formula
Wh = Ah × V
kWh = Ah × V ÷ 1000 · Reverse: Ah = Wh ÷ V = (kWh × 1000) ÷ V · Ah = mAh ÷ 1000.
- Ah — amp-hours (charge capacity).
- V — nominal battery voltage (volts).
- Wh — watt-hours (energy).
Example: 100 Ah × 12 V = 1200 Wh (1.2 kWh).
Need hours at a load? Battery runtime calculator. UPS string Ah: UPS battery calculator.
When to use which battery tool
| Goal | Tool |
|---|---|
| Convert Ah ↔ Wh (unit conversion) | This page — Ah to Wh |
| DC pack hours from Ah / V / load | Battery runtime calculator |
| UPS Ah for target backup minutes | UPS battery sizing |
| Series/parallel string layout | UPS battery bank |
Common mistakes when converting Ah to Wh or kWh
- Treating amp-hours as energy. Ah measures charge; energy needs voltage. The same 100 Ah block is 1.2 kWh at 12 V and 4.8 kWh at 48 V, so a Wh/kWh answer without a stated voltage is not an answer.
- Misplacing the 1000 between Wh and kWh. 1200 Wh and 1.2 kWh are the same quantity. Entering one while reading the other moves the result by three decimal places, which is the single most common source of a wrong procurement figure.
- Using a non-nominal voltage. The conversion is defined on nominal voltage (12 V lead-acid, 12.8 V LiFePO4), not on charging voltage or a surface reading taken while the bank is on float.
- Adding amp-hours across a series string. Series connections add voltage and leave Ah unchanged; parallel strings add Ah. Summing Ah on a series string overstates the bank by the string count.
- Assuming amp-hours imply a runtime. Ah alone says nothing about discharge time. The rated hour rate (C20 vs C5) decides how much of the nameplate amp-hours is actually delivered at your load.
Frequently Asked Questions
How do I convert Ah to kWh?
kWh = Ah × V ÷ 1000. Example: 100 Ah at 12 V = 1.2 kWh; 100 Ah at 48 V = 4.8 kWh. Select kWh as the energy unit in Wh→Ah mode, or read kWh on the Ah→Wh result card.
How do I convert kWh to amp hours?
Ah = (kWh × 1000) ÷ V. Example: 1.2 kWh at 12 V = 100 Ah. Use Wh→Ah mode with the kWh unit selected.
How many Wh is in an Ah?
1 Ah is not a fixed Wh—you need voltage: Wh = 1 × V. At 12 V → 12 Wh; at 24 V → 24 Wh; at 48 V → 48 Wh.
How much is 100Ah in Wh?
Wh = 100 × V. At 12 V = 1200 Wh (1.2 kWh); at 24 V = 2400 Wh; at 48 V = 4800 Wh. Use the reference table above for 120 Ah / 200 Ah rows too.
How do I convert ampere hours to watt hours?
Wh = Ah × V. Example: 100 Ah at 12 V = 1200 Wh (1.2 kWh). Voltage is required because amp-hours measure charge, not energy.
How do I convert watt hours to ampere hours?
Ah = Wh ÷ V. Example: 1200 Wh at 12 V = 100 Ah. Switch to Wh → Ah mode above.
How do I convert mAh to Ah or Ah to kWh?
Ah = mAh ÷ 1000 (2000 mAh = 2 Ah). kWh = (Ah × V) ÷ 1000—select mAh or kWh units above. Example: 100 Ah × 12 V = 1.2 kWh.
What is the amp hour formula?
Amp-hours measure charge: Ah = A × hours. Energy needs voltage: Wh = Ah × V. Average current from capacity and time: A = Ah ÷ hours on the Ah to amps calculator.
What is 100Ah in watts?
Ah alone is not watts. Energy is Wh = Ah × V (100 Ah × 12 V = 1200 Wh). Continuous power in watts depends on discharge rate; at roughly a 1C rate for one hour, power ≈ Ah × V (~1200 W at 12 V).
How many amp hours is 200W?
Watts are power. Capacity needs time: Ah ≈ (W × hours) ÷ V. Example: 200 W for 5 h at 12 V ≈ 83.3 Ah before DoD and losses—or use the battery runtime reverse-Ah mode.
Is Ah to Wh the same as a battery runtime calculator?
No. This page only converts energy units. For hours at a load use battery runtime. For Ah ÷ hours → amps use Ah to amps. For UPS minutes use UPS runtime.