How to Make an Anemometer

Meteorologists have a lot of tools they use to monitor and predict the weather to keep the public informed on what to expect when they walk out the door. An anemometer is one of those tools. It is used to measure the wind speed. As the wind blows, the anemometer rotates and since it is rotating at the same speed as the wind, this gives a very direct and simple measurement of how fast the wind is blowing. This is a fun project for any kid or adult who is interested in weather and wants to explore how this planet works a little more.


–         4 small paper cups

–         4 plastic straws

–         1 new pencil with eraser

–         1 straight pin

–         Tape

–         Scissors

–         Stapler


1. An anemometer has 4 cups that catch the wind, similar to a horizontal windmill. The cup will catch the wind and cause it to spin, the most spins that you count per minute the faster the wind is moving. First, you need to arrange the 4 drinking straws into a cross pattern and tape them together in the center. This will provide the axle for the anemometer.

2. Staple one side of the paper cups to the end of each straw, one cup per straw. The open end of the cups should all face in the same direction or the anemometer will not work properly.

3. Push the straight pin through the center of the straws in the middle of the cross. Push the pin into the eraser of the pencil. This will secure the structure together and will allow it to spin.

4. Mark one of the cups so that it is distinct from the other three. Something like a symbol with a colored marker on the side of the cup will work just perfectly. This cup will be used to count the number of rotations. When that cup makes one full circle, which will count as one rotation.

5. Test the anemometer by putting it in front of a fan or blowing lightly to be sure that it spins easily and is not impeded by anything.

Using the Anemometer

In order to accurately determine the speed of the wind, you will need to count how many rotations the anemometer makes in one minute. Ten rotations is equal to around one mile per hour. This is not an exact measurement and if you want to be more precise; you should compare your home-made anemometer to a professional one to compare your readings. Once you have measured the amount of rotations per minute, then this can be extrapolated into how many miles per hour the wind is moving. This can be transferred to the Beaufort Wind Scale to determine the force of that wind. For example, less than 5 miles per hour is considered a calm day for wind while over 62 miles per hour is officially a gale force wind.

Wind speed is not only important for making decisions about the day-to-day weather but also for wind energy. In a world that is constantly looking for more sustainable ways to get energy, wind energy is one of the more promising areas. In order for a wind turbine to work, it needs a constant speed of wind in order to generate energy. This is why meteorologists are needed to determine the areas that get that constant wind speed to build the expensive wind farms.