What does the C-rating mean?

The C-rating tells you the maximum safe continuous discharge rate. A 30C 5000mAh battery can deliver 30 x 5 = 150 amps continuously. Higher C-ratings mean the battery can deliver more current without overheating or puffing. Always choose a battery with a C-rating that exceeds your motor maximum draw.

How many cells (S) do I need?

The cell count determines voltage. 2S (7.4V) suits smaller models. 3S (11.1V) is the most common for general RC use. 4S (14.8V) and 6S (22.2V) are used for high-performance models. Match the cell count to your ESC and motor specifications.

Why do I only get 80% of the rated capacity?

Discharging a LiPo below 3.3V per cell damages it permanently. The usable capacity is about 80% of the rated capacity. Never run a LiPo flat — use a low-voltage alarm. For maximum lifespan, some pilots only use 70% of capacity.

How do I calculate run time?

Run time (mins) = (Usable capacity in Ah / Average current draw in A) x 60. For example, a 5000mAh battery at 80% usable (4000mAh) with 20A average draw gives 0.2 hours = 12 minutes. Actual run time varies with throttle usage.

ModelCalcs

Battery Calculator — RC Power Planning

Calculate battery capacity, C-rating, discharge rate and run time for your RC model.

Capacity (mAh)

Printed on the pack label, e.g. 2200, 3300 or 5000 mAh.

Cell Count (S)Cells in series (S). Pack voltage = cells × nominal cell voltage; match your ESC and motor voltage range.

Battery TypeCell chemistry — sets the nominal voltage per cell used for voltage and Wh.

C-Rating

Continuous discharge rating printed on the pack, e.g. 30C, 50C.

Average Current Draw (A)

Typical average during use

How We Calculate This

Calculates battery voltage, maximum current delivery and estimated run time from battery specifications.

Formula

Voltage = Cell count × Nominal cell voltage (set by chemistry: LiPo 3.7 V, LiHV 3.8 V, Li-ion 3.6 V, LiFe 3.2 V, NiMH 1.2 V per cell)
Max current = (Capacity mAh ÷ 1000) × C-rating
Watt-hours = (Capacity / 1000) × Voltage
Run time = (Capacity × usable% ÷ 100) ÷ (Avg current × 1000) × 60 mins (usable defaults to 80%)

Frequently Asked Questions

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Servo Torque Calculator

Determine the servo torque needed for your control surfaces or steering.

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Calculate wing loading to predict flight characteristics and stall speed.

Last updated: February 2026

All calculations are estimates. Always verify quantities before purchasing materials.