Watt-hour Calculator
Calculate energy consumption in watt-hours from battery capacity or power usage over time
Calculate Watt-hours
Battery Capacity
From voltage and charge (mAh/Ah)
Formula: Wh = V × Ah
Power × Time
From power consumption and time
Formula: Wh = W × hours
Nominal voltage of the battery
Battery capacity in milliamp-hours or amp-hours
Energy Calculation Results
Formula used: Wh = 0V × 0.000Ah = 0.00Wh
Example Calculations
Example 1: Smartphone Battery
Battery: 3000 mAh, 3.7V lithium-ion
Calculation: Wh = 3000 mAh × 3.7V ÷ 1000 = 11.1 Wh
Usage: Can power phone for ~8-12 hours typical use
Example 2: LED Light Bulb
Power: 9W LED bulb, 8 hours daily
Calculation: Wh = 9W × 8h = 72 Wh per day
Monthly cost: (72 × 30) ÷ 1000 × $0.15 = $0.324
Example 3: Laptop Battery
Battery: 5000 mAh, 11.1V lithium polymer
Calculation: Wh = 5 Ah × 11.1V = 55.5 Wh
Runtime: ~6-8 hours depending on usage
Common Battery Types
Energy Conversions
Quick Formulas
Understanding Watt-hours and Energy Consumption
What is a Watt-hour?
A watt-hour (Wh) is a unit of energy that represents the amount of energy consumed by a device that uses one watt of power for one hour. It's commonly used to measure battery capacity and electrical energy consumption.
Key Concepts
- •Energy vs Power: Wh measures energy (total), W measures power (rate)
- •Battery Capacity: Higher Wh = longer runtime
- •Electricity Bills: Charged per kWh consumed
Practical Applications
Battery Comparison
- • Compare different battery technologies
- • Estimate device runtime
- • Plan backup power requirements
- • Solar system battery sizing
Energy Management
- • Calculate electricity costs
- • Monitor appliance consumption
- • Optimize energy usage
- • Plan renewable energy systems
Why Convert mAh to Wh?
Accurate Comparison
Different batteries operate at different voltages. A 3000mAh battery at 3.7V (11.1Wh) has more energy than a 3000mAh battery at 1.2V (3.6Wh).
Real-world Planning
Watt-hours tell you actual energy available for your devices, helping you plan backup power, portable systems, and energy budgets accurately.