Battery conversion tool
Battery Ah and Wh Calculator
Convert between amp-hours and watt-hours from battery voltage on one bidirectional worksheet.
Convert Battery Ah and Wh
Convert nominal battery capacity between amp-hours and watt-hours before reviewing runtime, inverter, UPS, or solar assumptions.
Result
Watt-hours
4,800 Wh
Result notes
Keep the entered values, assumptions, and result together when adding this calculation to job notes or submittal records. Final installation choices should align with the applicable code edition, equipment listing, manufacturer instructions, local amendments, and AHJ requirements.
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Related charts
Battery Capacity Runtime Chart
Use this battery runtime chart for 12 V x 100 Ah = 1,200 Wh, 80% DoD = 960 Wh, 400 W load = 2.4 h, and module-count checks.
UPS Backup Time Chart
Use this UPS runtime chart: 2.4 kWh usable battery at 1,000W load gives about 144 min; record VA, watts, battery age, and transfer plan.
Electrical Unit Conversion Chart
Use this electrical unit conversion chart for 500 mA = 0.5 A, 2 kW = 2,000 W, 3 kWh = 3,000 Wh, ohms, uF/F, and calculator checks.
Related guides
Battery Capacity Formula Guide | 10 kWh to 32.7 kWh
Calculate battery size: 10 kWh/day for 2 days at DoD 0.80, efficiency 0.90 and temp 0.85 needs 32.7 kWh; UPS 200Ah 48V = 4.4h.
Electrical Energy Fundamentals for kWh, Demand, and Usage Review
Use power, runtime, duty cycle, kWh, and demand concepts to review energy use, battery capacity, and utility-bill math in U.S. electrical work.
Formula and field context
Convert between amp-hours and watt-hours from battery voltage on one bidirectional worksheet.
Formula context
Battery Capacity Runtime Chart
A battery capacity runtime chart is a planning worksheet: 12 V x 100 Ah = 1,200 Wh, 80% DoD = 960 Wh, and a 400 W load = 2.4 h before reserve and module-count checks.
Formula
Runtime hours = usable battery Wh / load watts. Battery units in series = ceil(bank voltage / unit voltage). Parallel strings = ceil(required Ah / unit Ah).Variables to keep with the result
- Usable battery Wh is nominal energy after depth-of-discharge, aging, temperature, and efficiency factors.
- Load watts are the connected real-power load being backed up.
- Battery voltage and amp-hours define nominal stored energy.
- Battery unit voltage and Ah convert the bank screen into series count, parallel strings, and total unit count.
- Reserve notes capture planned unused capacity and end-of-life allowance.
Formula and variables
Watt-hours equal amp-hours multiplied by nominal battery voltage. The reverse calculation divides watt-hours by voltage. The result is a capacity conversion, not a usable-runtime guarantee, because depth of discharge, inverter efficiency, temperature, age, and BMS limits affect usable energy.
Backup power example
A 100 Ah battery bank at 48 V has a nominal capacity of 4,800 Wh. That does not mean every watt-hour is available for the connected load. A practical worksheet should also document chemistry, usable depth of discharge, system efficiency, and manufacturer limits.
When to use the full calculator
Use the battery-capacity calculator for runtime, autonomy, depth of discharge, system efficiency, and battery type. Use inverter and UPS calculators when AC loads or conversion losses are part of the design.