What is depth of discharge (DoD)?

Depth of discharge is the percentage of a battery's capacity you can use before recharging. Lead-acid batteries degrade quickly below 50% DoD, so 50% is the practical limit. Lithium (LiFePO4) batteries can safely discharge to 80–90%. Always check your battery spec sheet.

How do I estimate my daily energy consumption?

List each appliance, multiply its wattage by hours of daily use to get Wh, then sum them all. For example: a 50W fan for 8 h = 400 Wh, plus a 10W LED for 5 h = 50 Wh, total = 450 Wh/day.

Why does system voltage affect the Ah figure?

Energy (Wh) = Voltage (V) × Capacity (Ah). At 48V you need fewer Ah for the same kWh, which means thinner wiring and lower current. Higher voltage systems are generally more efficient for larger installations.

What autonomy days should I use?

Two to three days is common for solar systems in temperate climates. Off-grid cabins in cloudy regions often plan for 4–5 days. Grid-backup systems typically need only 1–2 days.

Does this account for inverter efficiency?

No. Real systems lose 5–15% to inverter inefficiency. To compensate, multiply your daily consumption by 1.1 to 1.2 before entering it here.

Battery Storage Sizing Calculator

Name: Battery Storage Sizing Calculator
Availability: InStock
Author: Nham Vu

Enter your daily energy use, autonomy days, depth of discharge, and system voltage to get the required battery bank size in kWh and Ah.

System Parameters

Daily Energy Consumption

Sum of all appliance watt-hours per day.

Days of Autonomy

Days the battery must supply power without recharging.

Depth of Discharge (DoD) 80%

10% Lead-acid: 50% | Lithium: 80–90% 100%

System Voltage

Quick Presets

Enter your system parameters and click Calculate.

Summary

Enter your daily energy use, autonomy days, depth of discharge, and system voltage to get the required battery bank size in kWh and Ah.

How it works

Enter your total daily energy consumption in watt-hours (Wh) or kilowatt-hours (kWh).
Set the number of autonomy days — how many days the battery must supply power without charging.
Enter the usable depth of discharge (DoD) as a percentage. Lead-acid batteries typically allow 50%; lithium batteries allow 80–90%.
Select your system voltage (12V, 24V, or 48V) to get the capacity in ampere-hours (Ah).
The calculator divides total energy demand by DoD to find gross capacity, then converts to Ah using system voltage.

Use cases

Size a battery bank for a solar cabin or tiny house running 2–5 days without sun.
Verify whether an existing battery bank meets autonomy requirements before installation.
Compare 12V, 24V, and 48V bank configurations to choose the most practical wiring.
Plan a grid-tied backup battery to ride out 1–2 day outages.
Spec a marine or RV battery system for a weekend without shore power.

Frequently Asked Questions

Last updated: 2026-07-04 · Reviewed by Nham Vu