Wh to Ah Calculator

The number of Watt-hours (Wh) in an Ampere-hour (Ah) depends directly on system operating voltage, governed by the formula Wh = Ah × Voltage. For example, 1 Ah at 12V equals 12 Wh, whereas 1 Ah at 24V equals 24 Wh, and 1 Ah at 48V equals 48 Wh. Without specifying the nominal battery voltage, an Ampere-hour rating alone cannot be converted into Watt-hours.

To convert Watt-hours (Wh) into Ampere-hours (Ah), divide the total stored energy in Watt-hours by nominal battery voltage using Ah = Wh ÷ V. For instance, a 500 Wh portable solar power station operating on a 12V DC system delivers 500 ÷ 12 = 41.67 Ah of capacity. If the same 500 Wh generator uses a 36V e-bike battery pack, it equals 13.89 Ah.

A 100Ah battery rating converts to Watt-hours by multiplying by the battery's nominal voltage. A standard 12V 100Ah lead-acid or AGM battery yields 100 Ah × 12 V = 1,200 Wh (1.2 kWh). A 12.8V 100Ah LiFePO4 lithium battery yields 1,280 Wh (1.28 kWh). A 24V 100Ah battery bank yields 2,400 Wh (2.4 kWh), and a 48V 100Ah server rack battery delivers 4,800 Wh (4.8 kWh).

To convert between Wh and Ah, you must incorporate system voltage. Multiply Ah by voltage to calculate Wh (e.g. 1 Ah at 24V equals 24 Wh). Conversely, divide Wh by voltage to calculate Ah (e.g. 120 Wh divided by 12V equals 10 Ah). This linear relationship explains why higher-voltage battery systems require lower Ah ratings for identical total energy storage.

A 4 Ah battery rating converts to Wh depending on voltage. In a 12V power tool battery pack, 4 Ah equals 4 × 12 = 48 Wh. In an 18V power tool battery pack, 4 Ah equals 4 × 18 = 72 Wh. In a single 3.7V smartphone lithium-ion cell, 4 Ah (4,000 mAh) equals 4 × 3.7 = 14.8 Wh.

A 256 Wh battery bank operating on a 12.8V LiFePO4 (Lithium Iron Phosphate) chemistry yields 256 ÷ 12.8 = 20 Ah of charge capacity. If connected across a standard 12V lead-acid system, 256 Wh produces 256 ÷ 12 = 21.33 Ah.

A 120Ah battery rated at a nominal 12 Volts stores 120 Ah × 12 V = 1,440 Wh (1.44 kWh) of energy. If the 120Ah battery is a 24V marine bank, total energy capacity equals 120 × 24 = 2,880 Wh (2.88 kWh).

At 12V DC, 160 Wh equals 160 ÷ 12 = 13.33 Ah. In a 14.8V drone or camera battery, 160 Wh equals 160 ÷ 14.8 = 10.81 Ah. Note that 160 Wh is the absolute maximum battery size allowed on commercial flights under FAA/ICAO regulations with airline approval.

Wh and Ah measure different physical properties and cannot be directly compared without knowing voltage. Ampere-hours (Ah) measure electric charge capacity, whereas Watt-hours (Wh) measure total stored electrical energy. Wh provides a true universal energy comparison across different battery voltages; for example, a 12V 100Ah battery (1,200 Wh) stores twice as much energy as a 12V 50Ah battery (600 Wh).

Convert Ah to Wh by multiplying the battery capacity in Ampere-hours by nominal system voltage: Wh = Ah × V. For example, a 100 Ah 12V battery stores 100 × 12 = 1,200 Wh of energy. Multiply by 1,000 if converting Ah directly into kilowatt-hours (kWh = Wh ÷ 1000).

A standard 12.8V 100Ah LiFePO4 (Lithium Iron Phosphate) battery stores 100 Ah × 12.8 V = 1,280 Wh (1.28 kWh) of gross energy. Because lithium batteries allow up to 80%-90% depth of discharge (DoD) without damage, virtually all 1,280 Wh is usable, compared to only 600 Wh usable energy in a 100Ah lead-acid battery.

No. 200 Watts (W) represents power draw rate (instantaneous power consumption), whereas 200 Watt-hours (Wh) represents total energy consumed or stored over time. For example, running a 200-Watt appliance continuously for 1 hour consumes exactly 200 Watt-hours of energy (200 W × 1 h = 200 Wh).

Apply the standard battery energy formula: Watt-hours = Ampere-hours × Voltage. Simply locate your battery's nominal voltage (typically 3.7V, 12V, 24V, or 48V) and multiply it by the rated Ah capacity printed on the battery label.

A 12V 100Ah battery stores 1,200 Wh (100 Ah × 12 V = 1,200 Wh). Accounting for a typical DC-to-AC inverter efficiency of 85% yields 1,020 usable Wh. Operating a 500-Watt load yields a continuous runtime of 1020 Wh ÷ 500 W = 2.04 hours (approx. 2 hours and 2 minutes).

1,000 Wh is equal to 1 Kilowatt-hour (1 kWh). In battery capacity, 1,000 Wh equals 83.33 Ah at 12 Volts, 41.67 Ah at 24 Volts, or 20.83 Ah at 48 Volts. It is sufficient energy to run a 100W TV for 10 hours or a 500W refrigerator for 2 hours.

20,000 mAh equals 20 Ah (divide mAh by 1,000). Portable power banks utilize internal 3.7V lithium-ion cells, so total energy equals 20 Ah × 3.7 V = 74 Wh. Because 74 Wh is below the 100 Wh airline threshold, 20,000 mAh power banks are approved for airplane cabin travel.