Battery Ampere-hour (Ah) Calculator
Calculate battery capacity in Ampere-hours from current, discharge time, or Watt-hours and voltage.
Battery Ampere-hour (Ah) Calculator
Compliant with IEEE 1188 Standards
Results:
Ampere-hour (Ah): 0.00
How to Use the Calculator
Calculate from Current & Discharge Length
- Select "Current & Discharge Length" as the calculation method.
- Enter the current flow in Amps (A).
- Provide the discharge length in hours (h).
- Click "Calculate" to get the Ampere-hour (Ah).
Calculate from Watt-hour & Voltage
- Select "Watt-hour & Voltage" as the calculation method.
- Enter the Watt-hour (Wh) capacity.
- Provide the Battery Voltage (V).
- Click "Calculate" to get the Ampere-hour (Ah).
General Tips
- Ensure all input values are positive numbers.
- Use the "Reset" button to clear all fields and results.
- Ampere-hour (Ah) is a measure of battery charge capacity.
How to Convert Battery Ampere-hour (Ah)
Translate current, time, and energy specs into accurate Ah ratings.
1. Gather Inputs
Record the load current (amps), discharge time (hours), and optionally the battery energy (Wh) and voltage.
- Current method needs amps + hours.
- Energy method needs watt-hours + volts.
2. Use the Right Formula
Choose the equation that matches your known values.
- Ah = Current (A) × Time (h).
- Ah = Watt-hours (Wh) ÷ Voltage (V).
3. Real-Life Example
Running a 6A load for 8h at 24V.
- Ah (current method) = 6A × 8h = 48Ah.
- Wh = 6A × 24V × 8h = 1,152Wh.
- Ah (energy method) = 1,152Wh ÷ 24V = 48Ah.
4. Adjust for Conditions
Consider depth of discharge, temperature, and aging when specifying usable Ah.
- Lead-acid usable Ah ≈ rated Ah × 0.5 (50% DoD).
- Lithium usable Ah ≈ rated Ah × 0.8–0.9.
Battery Ampere-hour (Ah) Reference Chart
Estimate runtime using Ah = Current × Time for common scenarios.
12V Loads
| Load (A) | Time (h) | Ah Needed |
|---|---|---|
| 5 A | 10 h | 50 Ah |
| 10 A | 8 h | 80 Ah |
| 15 A | 6 h | 90 Ah |
| 20 A | 5 h | 100 Ah |
24V Loads
| Load (A) | Time (h) | Ah Needed |
|---|---|---|
| 5 A | 12 h | 60 Ah |
| 8 A | 10 h | 80 Ah |
| 12 A | 8 h | 96 Ah |
| 15 A | 7 h | 105 Ah |
Energy-Based
| Wh | Voltage | Ah |
|---|---|---|
| 600 Wh | 12 V | 50 Ah |
| 1,200 Wh | 24 V | 50 Ah |
| 2,400 Wh | 48 V | 50 Ah |
| 4,800 Wh | 48 V | 100 Ah |
Multiply Ah by the number of parallel strings or adjust for usable DoD to size real-world banks.
Battery Ampere-hour FAQs
Answers to common Ah conversion and sizing questions.
How to calculate battery Ah capacity?
Multiply the discharge current (amps) by the discharge time (hours). For example, a 6A load running 10 hours requires 60Ah.
How many hours is 1 Ah?
Runtime = Ah ÷ Load (A). One amp-hour will power a 1A load for one hour, a 0.5A load for two hours, or a 2A load for 0.5 hours.
What is the formula for Ah?
Use Ah = Current (A) × Time (h). Alternatively, Ah = Watt-hours (Wh) ÷ Voltage (V) when energy data is available.
How to calculate Ah from amps?
Multiply the current draw (amps) by the number of hours you expect to run the load. Example: 8A × 4h = 32Ah.
How many Ah is in 1 ampere?
Ampere-hour combines current and time. One ampere sustained for one hour equals 1Ah; one ampere for 30 minutes equals 0.5Ah.
What does 150Ah battery mean?
It can theoretically supply 150 amps for one hour, 15 amps for 10 hours, or any amps × hours product that equals 150, subject to discharge-rate limits and depth-of-discharge recommendations.