Choosing motors and propellers for a multirotor starts with thrust. To hover, the motors together must lift the whole drone; to climb, turn and fight wind they need a reserve. Builders express that reserve as the thrust-to-weight ratio: at 2:1 the motors can produce twice the drone’s weight, so it hovers at about half throttle.
A ratio of 2:1 is the minimum for a stable, controllable aircraft such as a camera or mapping drone. Around 3:1 gives a lively all-rounder, 4:1–5:1 suits FPV freestyle and racing, and acrobatic racers reach 7:1 or more. Too low a ratio leaves no headroom for gusts or for the battery’s voltage dropping late in a flight; too high a ratio wastes weight and makes the drone twitchy at low throttle.
Motor makers publish thrust tables – grams of thrust at full throttle for a given propeller and battery voltage. Pick a motor and propeller combination whose maximum thrust meets or exceeds the per-motor figure here. Remember that the motors themselves add weight: if you change to heavier motors, add their weight and check again.
How to use the Drone Motor Calculator
- Weight input
- Frame, motors, propellers and electronics
- Battery
- Payload (camera, gimbal, other equipment)
- Total (all-up) weight
- Thrust-to-weight ratio — 2:1 gentle flying, 3:1 all-round, 4–5:1 FPV, 7:1 and up for acrobatics.
- Number of motors
Results update as you type, every field has its own unit menu, and everything is calculated in your browser.
How it works
Enter the weight of the frame and electronics, the battery and the payload (or the total), choose the thrust-to-weight ratio and the number of motors. The calculator adds the weights, multiplies by the ratio and divides by the motor count.
Worked example
A quadcopter has a 500 g frame with motors and electronics, a 150 g battery and a 50 g camera: 700 g in total. At a 3:1 ratio the motors must produce 2,100 g together, or 525 g per motor. If heavier motors add 15 g in total, the weight becomes 715 g and each motor needs 715 × 3 ÷ 4 = 536 g.
Recommended ratios
| Use | Thrust-to-weight | Hover throttle |
|---|---|---|
| Camera, mapping, heavy lift | 2:1 | ≈ 50% |
| All-round hobby | 3:1 | ≈ 33% |
| FPV freestyle | 4:1–5:1 | 20–25% |
| Racing, acrobatics | 7:1 and up | < 15% |
Inputs explained
| Field | What to enter |
|---|---|
| Weight input | Choose one: Add up the parts, I know the total weight |
| Frame, motors, propellers and electronics | Units: g, kg, oz, lb |
| Battery | Units: g, kg, oz, lb |
| Payload (camera, gimbal, other equipment) | Units: g, kg, oz, lb |
| Total (all-up) weight | Units: g, kg, oz, lb |
| Thrust-to-weight ratio | In : 1. 2:1 gentle flying, 3:1 all-round, 4–5:1 FPV, 7:1 and up for acrobatics. |
| Number of motors | Choose one: 3 – tricopter, 4 – quadcopter, 6 – hexacopter, 8 – octocopter |
What each result means
- Total thrust needed = [All-up weight]×[Thrust-to-weight ratio]
- Thrust needed per motor = [Total thrust needed]÷[Number of motors]
- Thrust per motor to hover = [All-up weight]÷[Number of motors]
- Approximate hover throttle = 100÷[Thrust-to-weight ratio]
Formula
Total thrust = all-up weight × thrust-to-weight ratio · thrust per motor = total thrust ÷ number of motors · hover throttle ≈ 1 ÷ ratio
Worked example
Inputs — Weight input: Add up the parts; Frame, motors, propellers and electronics: 500 g; Battery: 150 g; Payload (camera, gimbal, other equipment): 50 g; Thrust-to-weight ratio: 3 : 1; Number of motors: 4 – quadcopter.
Results — All-up weight = 700 g; Total thrust needed = 2,100 g; Thrust needed per motor = 525 g; Thrust per motor to hover = 175 g; Approximate hover throttle = 33.3 %; Suitable for = Agile all-round flying (3:1).
Key terms
- Thrust-to-weight ratio
- Maximum total thrust divided by the drone's weight.
- All-up weight
- Total flying weight including battery and payload.
- Hover throttle
- Throttle setting at which thrust equals weight.
- Thrust table
- Manufacturer data of thrust, current and power for a motor and propeller.
Frequently asked questions
What thrust-to-weight ratio does a drone need?
At least 2:1; 3:1 for agile flying, 4:1–5:1 for FPV freestyle and racing.
How much thrust does each motor need?
Total weight × ratio ÷ motors – a 700 g quad at 3:1 needs 525 g per motor.
Why is a ratio of 1:1 not enough?
The drone could only just hover at full throttle, leaving nothing for control, climbing or wind.
How do I read a motor thrust table?
Find the row for your propeller and battery voltage; the full-throttle thrust in grams must exceed the per-motor value.
Does adding motors increase efficiency?
Not necessarily – more motors add redundancy (hexa/octo) but also weight; larger propellers on fewer motors are usually more efficient.
How does hover throttle relate to the ratio?
Roughly hover throttle ≈ 1 ÷ ratio, so 2:1 hovers near 50% and 4:1 near 25%.