EV Battery Pack Sizing Calculator

Formula

• Pack energy (Wh) = range × Wh/km
• Cell count = ceil(pack energy / cell Wh)
• Cell Wh = voltage × Ah
• Thermal load ≈ I_max × V_pack × 10% loss

About this calculator

Part of our EV & Renewable Calculators collection. Battery sizing, solar panel tilt, wind turbine performance, and EV drivetrain estimates.

How it works

Required pack energy equals target range times vehicle efficiency. Cell count comes from total energy divided by single-cell energy. Pack voltage and thermal load give a first-pass electrical and cooling estimate. Confirm with your BMS and cell datasheet limits.

Enter your values in the inputs above and click CALCULATE. Results appear on the right without a page reload. No login and no server upload.

Worked example

300 km range, 180 Wh/km, 3.7 V 2.5 Ah cells, 3C discharge.

1. Pack energy = 300 × 180 = 54 000 Wh = 54 kWh
2. Cell energy = 3.7 × 2.5 = 9.25 Wh
3. Cells needed = ceil(54 000 / 9.25) = 5838

Result: 54 kWh pack, 5838 cells required.

When to use

• First-pass EV pack sizing from range target
• Estimating cell count for module layout
• Rough thermal load for cooling concept

Limitations

• Pack voltage estimate is simplified; use your series/parallel layout
• Does not include BMS overhead, aux loads, or temperature derating
• Cell count blocks assume 100-cell grouping for planning only

FAQ

What Wh/km should I use?

Compact EVs often use 150–200 Wh/km. Larger vehicles or cold climates may need 200–250 Wh/km.

Is pack voltage accurate?

Pack voltage is a rough estimate from total energy and cell Ah. Size series groups from your target system voltage (400 V, 800 V, etc.).