Battery Capacity Calculator
Determine how much energy your battery can store and deliver for solar systems, inverters, or backup power with accuracy.
Capacity Sizing Tool
How to Use Battery Capacity Calculator
Follow these simple steps to determine the energy storage requirement for your power setup:
- Step 1: Enter Battery Voltage (V) – Provide your system voltage (e.g., 12V, 24V, or 48V).
- Step 2: Enter Load Power (Watts) – Input the total wattage of all connected devices.
- Step 3: Enter Backup Time (Hours) – Specify how long you need the battery to run.
- Step 4: Enter Efficiency (Optional) – Use 0.8 or 80% for realistic results accounting for losses.
- Step 5: Click Calculate – The tool will display the required capacity in Ah and total energy in Wh.
Tip: Always add 20–30% extra capacity for safety and to extend battery lifespan.
Battery Capacity Calculation Guide
Understanding the math behind battery sizing helps in designing more reliable backup systems. The capacity is calculated based on total energy consumption divided by system voltage and efficiency.
Formula:
Step-by-Step Example:
Given a scenario where you have:
- Load Power = 100 Watts
- Backup Time = 5 Hours
- Battery Voltage = 12V
- Efficiency = 0.8
Step 1: Multiply Load Power and Time
100W × 5h = 500 Wh (Watt-hours)
Step 2: Multiply Voltage and Efficiency
12V × 0.8 = 9.6
Step 3: Divide
500 / 9.6 = 52.08 Ah
Final Answer: Required Battery Capacity ≈ 52 Ah. For practical use, choosing a 60Ah or higher battery is recommended.
Battery Capacity Conversion Chart
Quick lookup table for battery energy storage at different voltages and capacities (Wh = V × Ah):
| Voltage | Capacity (Ah) | Energy (Wh) |
|---|---|---|
| 12V | 50 Ah | 600 Wh |
| 12V | 100 Ah | 1200 Wh |
| 12V | 200 Ah | 2400 Wh |
| 24V | 50 Ah | 1200 Wh |
| 24V | 100 Ah | 2400 Wh |
| 24V | 200 Ah | 4800 Wh |
| 48V | 50 Ah | 2400 Wh |
| 48V | 100 Ah | 4800 Wh |
| 48V | 200 Ah | 9600 Wh |
FAQs – Battery Capacity Calculator
A Battery Capacity Calculator helps you find how much energy a battery can store and supply based on load and time. It is essential for sizing backup systems correctly.
Ah (Amp-hours) measures current capacity over time, while Wh (Watt-hours) measures total energy. You can convert them using the formula: Wh = V × Ah.
It depends on your total electrical load, required backup time, and system voltage. Using an accurate calculator ensures you don't undersize your system.
Inverters and batteries lose energy as heat during discharging. Including an efficiency factor (usually 0.8) ensures your capacity estimate is realistic and safe.
Yes. It works perfectly for sizing solar battery banks, inverters, UPS systems, and any other battery-backed power setup.
The battery will drain faster than required and may suffer damage due to deep discharge, which significantly shortens its lifespan.
Yes. Adding 20–30% extra capacity is a best practice. It provides a safety margin for unexpected loads and increases the long-term reliability of the system.