# Drone Motor Calculator

Created by Krishna Nelaturu
Last updated: Sep 21, 2022

This drone motor calculator will help you choose the perfect motor for your drone. You've come to the right place if your drone design calculations are tedious. You will learn how to calculate the thrust for your drone and select the suitable motor for it in this article.

We also have another interesting tool called arrow speed calculator which helps to analyze the speed, and kinetic energy of arrows shot from a bow.

## Drone weight calculation

The first thing to consider while designing a drone is its weight. Understandably, you won't know the precise weight until you decide on the motors. But starting with a rough estimate of the drone's weight will make drone design calculation easier.

We can split the total weight of the drone into three main categories:

1. Drone weight includes the weight of the frame, motors, propellers, landing gear, etc.
2. Battery weight.
3. Equipment weight includes any additional equipment such as cameras and lights.

## Thrust to weight ratio

Similar to power-to-weight ratio, the thrust-to-weight ratio measures how much thrust is available per unit mass of the drone. This is a design decision that you have to make based on the drone application. For example, if you're only planning on capturing aerial photos or videos while gently flying and hovering your drone, you should choose a thrust-to-weight ratio of 2:1. Drone motors are rated for thrust in grams or ounces. It is the maximum weight the motor can lift off the ground.

The following table is a collection of typical thrust-to-weight ratios for different applications.

These values are just for suggestion.

Application

Thrust-to-weight

Aerial photography

2:1

First-person view videos (FPV)

4:1

Drone races

5:1

Extreme acrobatic flying

7:1

## Drone thrust calculation: drone thrust formula

The total thrust required to make the drone fly is given by:

thrust = thrust-to-weight-ratio × total drone weight

From this, we determine the thrust required from each motor using:

thrust per motor = thrust/number of motors

For example, let's say your quadcopter drone weighs 800 g in total, and you chose a thrust-to-weight ratio of 4:1. Using the drone thrust formula:

• thrust = (4/1) × 800 = 3200 g.
• thrust per motor = 3200 g/4 = 800 g.

So you need four motors of 800 g thrust capacity.

## Selecting the right motor

Selecting a suitable motor after calculations is a game of balancing the weight and thrust requirements. Consider the following case:

Say you found an 800 g thrust motor that weighs 65 g each. However, say you initially estimated only 50 g per motor. Now, there is a 15 g excess per motor, or 60 g excess for four motors. Factoring this into our thrust calculator, you see that a total weight of 860 g requires 860 g of thrust from each motor. This makes the motor unsuitable for your design.

So you browse further for a lighter motor that can deliver 800 g thrust, and you get lucky! You find a motor of 830 g thrust weighing 50 g which gives your drone an excess 120 g thrust while keeping it light!

## Using this drone motor calculator

Our drone motor calculator is straightforward to use:

1. Enter the weight of your drone body, battery, and equipment. Alternatively, provide the drone's total weight.
2. Enter the thrust-to-weight ratio that you've chosen.
3. Input the number of motors used for propulsion. The drone motor calculator will perform the thrust calculations for your drone and display the answer immediately.

For your next challenge, try your hand at designing a rocket! Our rocket thrust calculator will come in handy.

Krishna Nelaturu
Weight
Drone weight
lb
Battery weight
lb
Equipment weight
lb
Total weight
lb
Thrust
Thrust-to-weight ratio
:1
Number of motors
Total thrust
lb
Thrust per motor
lb
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