Free RC Calculators
Work out your RC car's top speed, your LiPo's run time and charge time, your gas and oil mix, or the real size of a scale model.
Every calculator runs in your browser, needs no sign-up and shows the formula it uses, so you can check the result yourself.
Speed and gearing
- RC car speed calculator: enter the motor kV, the number of LiPo cells, the pinion, the spur gear and the wheel diameter to get the theoretical top speed and the final drive ratio.
LiPo batteries
- RC battery run time calculator: how many minutes your battery will last based on its capacity and the model’s average current draw.
- LiPo charge time calculator: how long a battery takes to charge and what current equals 1C.
- LiPo voltage calculator: nominal, fully charged, storage and minimum voltage by cell count, plus state of charge from a measured voltage.
Gas engines
- Gas oil mix calculator: how much two-stroke oil you need to hit the ratio your 1/5 scale engine calls for.
Scale
- RC scale converter: convert real-world measurements to scale (1/5, 1/8, 1/10…) and back.
If you want to understand the concepts behind them in depth, check out our RC electronics section and the guide to RC car scales.
Guides on this topic
- RC Car Speed CalculatorEnter the motor kV, battery cells, pinion, spur gear and tire size to see your RC car's theoretical top speed.
- RC Battery Run Time CalculatorWork out how many minutes your RC model's battery lasts from its capacity in mAh and its average current draw.
- LiPo Charge Time CalculatorHow long your LiPo battery takes to charge, based on its capacity, the charger current and the charge left in it.
- LiPo Voltage Calculator by Cell CountNominal, maximum, storage and minimum voltage of your LiPo by cell count, and what state it's in based on the voltage you measure.
- Gas-Oil Mix Calculator for 2-Stroke RC EnginesHow much 2-stroke oil to add to the gas for your 1/5 scale RC car, based on the ratio your engine calls for.
- RC Scale ConverterConvert real-world sizes to the scale of your RC model (1/5, 1/8, 1/10…) and work out the equivalent real size of a model.
Frequently asked questions
Are the calculators free?
Yes. They run in your browser, with no sign-up, and the numbers you enter aren't sent anywhere.
How accurate are the results?
The formulas are exact for the numbers you enter, but a real RC car loses performance to weight, air drag, temperature and battery condition. Treat the results as well-grounded estimates, not measurements.
Can I use them for planes, boats or drones?
The LiPo battery calculators (run time, charging and voltage) work for any electric model. The speed calculator is designed for cars, and the mix calculator is for two-stroke gas engines.
Related guides
RC cars
RC LiPo Batteries: How to Choose, Charge and Care for Them
What the cell count (S), mAh and C rating on a LiPo battery mean, how to choose one for your RC car, plane or boat, and how to charge it, store it and tell when it's damaged.
4 min read
Free tool
Gas-Oil Mix Calculator for 2-Stroke RC Engines
How much 2-stroke oil to add to the gas for your 1/5 scale RC car, based on the ratio your engine calls for.
Free calculator