Plan Your LiPo Pack — Voltage, Runtime & Discharge

A free browser-based LiPo battery calculator for drone pilots, RC enthusiasts and robot builders. Enter capacity, cell count and C-rating to instantly see pack voltage (empty, nominal, fully charged), energy in Wh, maximum continuous discharge current and estimated flight or drive runtime. Supports current or power load input.

How to Use the LiPo Battery Calculator

Enter capacity and cell count

Type the battery capacity in mAh and select the number of cells (S). The pack voltage band appears immediately.

Add the continuous C-rating

Enter the continuous C-rating from your battery label. The calculator shows the maximum safe discharge current (mAh ÷ 1000 × C).

Enter your load for runtime

Type either the load current in amps or the total power draw in watts. Runtime is calculated at 80% usable capacity.

Check the warning banner

If your load exceeds the max continuous discharge, a red warning appears. Choose a higher C-rating battery or reduce the load.

Find runtime, discharge current and pack voltage for any LiPo configuration instantly

Capacity

mAh

Cell Count (S)

Continuous C-Rating

Load (optional — for runtime)

Runtime uses 80% usable capacity — fully draining a LiPo shortens its lifespan.

Charger Current

Charge Rate

Charge rate sets charger current as a multiple of capacity (e.g. 1C). Editing one updates the other.

Quick Presets

Features

Pack voltage in three states: cutoff (3.2V/cell), nominal (3.7V/cell) and fully charged (4.2V/cell) Energy (Wh) and max continuous discharge current from capacity and C-rating Runtime in minutes and h:mm format using the safe 80% usable capacity rule Over-discharge warning when load current exceeds the battery's continuous rating Three built-in presets: FPV drone, RC car, small robot Load can be entered as amps or watts — automatically converted via nominal voltage

FAQ

What does the S number mean?

S stands for series. Each LiPo cell has a nominal voltage of 3.7 V. A 4S pack has four cells in series, giving 4 × 3.7 = 14.8 V nominal voltage.

How is max discharge current calculated?

Max continuous discharge (A) = capacity (Ah) × C-rating. A 5000 mAh 25C pack can deliver 5 Ah × 25 = 125 A continuously.

Why does runtime use 80% capacity?

Discharging a LiPo below ~3.2 V per cell permanently damages cells and reduces lifespan. The 80% rule is the standard safety buffer for RC and drone use.

Can I enter watts instead of amps?

Yes. Toggle to Watts and enter total power draw. The tool divides watts by nominal voltage to derive load current, then calculates runtime normally.

What is the cutoff voltage?

The cutoff (or low-voltage disconnect) voltage is 3.2 V per cell — the safe minimum before the pack is considered empty. Flying or driving below this risks permanent cell damage.

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Published 18 May 2026 Updated 21 May 2026