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LiPo Battery Calculator

Calculate flight time, required C-rating, charge time, and safe voltage thresholds for RC drones and FPV aircraft.

Flight Time Calculator

Usable capacity
Voltage
Flight time (80% safe discharge)

Required C-Rating Calculator

Required C-rating
Max safe continuous amp draw
Safety status

Charge Time Calculator

Charge current
Charge time
Status

Cell Voltage Reference

These are the safe operating voltages for LiPo cells. Do not discharge below 3.0V per cell.

Cell countVoltageSafe minStorage
1S (1 cell)3.7V nominal
4.2V max		3.0V3.85V
2S (2 cells)7.4V nominal
8.4V max		6.0V7.7V
3S (3 cells)11.1V nominal
12.6V max		9.0V11.55V
4S (4 cells)14.8V nominal
16.8V max		12.0V15.4V
5S (5 cells)18.5V nominal
21.0V max		15.0V19.25V
6S (6 cells)22.2V nominal
25.2V max		18.0V23.1V

Safe minimum is 3.0V per cell at rest. Storage voltage extends battery life. Do not charge above the max voltage listed for your cells. Standard cells charge to 4.2V per cell. High voltage (HV) cells charge to 4.35V or 4.45V per cell and require a compatible charger.

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About LiPo battery calculations

Lithium polymer (LiPo) batteries power most RC drones and FPV aircraft. They are light and pack a lot of energy, but they require care. Calculating flight time, charge time, and safe discharge ensures your battery performs well and lasts.

Flight time depends on how much energy you can safely pull from the battery, divided by how much power your motors draw. The 80 percent rule is industry standard: only 80 percent of a LiPo's capacity should be discharged in flight to keep cells above 3.0 volts and preserve the battery for many charge cycles.

C-rating tells you how fast the battery can discharge. A 50C battery can discharge at 50 times its capacity. If you need more current than your battery can safely supply, it will overheat, swell, and potentially catch fire. This calculator warns you if your required C-rating exceeds the battery you have.

Charge time depends on how fast you charge. Charging at 1C (one times the capacity per hour) is the safe standard. Faster charging reduces battery life and increases heat. Always follow the battery's label for the maximum safe charge rate.

Cell voltage matters for safety and lifespan. Each LiPo cell is 3.7 volts nominal. At full charge it reaches 4.2 volts. The absolute minimum is 3.0 volts per cell. Exceeding these limits damages the battery and can cause thermal runaway.

LiPo safety essentials

Never discharge below 3.0 volts per cell. This is permanent damage territory. Many chargers have a storage mode that brings the pack to 3.7 to 3.85 volts per cell, which is the safe long-term storage voltage.

Charge at 1C if possible. Charging at 2C or faster is technically possible on quality batteries but shortens lifespan and generates heat. The battery label shows the maximum safe charge rate. Do not exceed it.

Do not use a battery that swells. If a battery puffs up during charge or discharge, stop using it immediately. Swelling is a sign the cell is damaged and at risk of venting or catching fire. Let it cool outdoors and dispose of it safely.

Use a quality charger. A charger that can balance-charge your battery keeps all cells at equal voltage, which extends lifespan and safety. Chargers also monitor temperature and can cut off charging if a cell gets too hot.

Store in a cool place. LiPo batteries degrade in heat. If you are not flying for weeks or months, bring the battery to 3.7 to 3.85 volts per cell and store it at room temperature or cooler. Check it every few weeks and recharge if the voltage drops below 3.6V per cell.

Common questions

How do you calculate LiPo battery flight time?

Flight time in minutes equals usable capacity in amp-hours divided by average current draw in amps, times 60. Usable capacity is 80 percent of rated capacity to keep the battery above 3.0 volts per cell. For example, a 5000 mAh (5 Ah) battery with 80 percent usable capacity is 4 Ah usable. At 20 amps average draw, that is 4 divided by 20 times 60 equals 12 minutes of flight.

What C-rating do I need for my LiPo battery?

Divide your average current draw in amps by your battery capacity in amp-hours. For example, if you draw 50 amps average from a 5 Ah battery, you need at least 50 divided by 5 equals 10C continuous rating. The battery manufacturer lists both continuous and burst ratings. Continuous rating is the safe limit for sustained flight. If your required C-rating exceeds the battery's continuous rating, the battery will overheat and risk damage or fire.

What is the safe minimum voltage for a LiPo battery?

The absolute minimum is 3.0 volts per cell at rest. However, practical flying usually stops around 3.2 to 3.5 volts per cell to preserve battery lifespan. Do not discharge LiPo cells below 3.0 volts per cell under any circumstances, as this causes permanent damage.

How long does it take to charge a LiPo battery safely?

At 1C charge rate, which is the safe standard, charging time in hours equals battery capacity in amp-hours divided by the charge current in amps. For example, a 5 Ah battery charged at 5 amps (1C) takes approximately 1 hour. Charging faster than 1C reduces battery life and increases heat and swelling risk. Always check the battery label for the manufacturer's recommended maximum charge rate.

What voltage should a LiPo battery be stored at?

Store LiPo batteries at 3.7 to 3.85 volts per cell, aiming for 3.85V if possible. This is approximately 40 to 60 percent state of charge and minimizes chemical degradation during long storage. Do not store fully charged or fully discharged.

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