How to Build Balloon-Powered LEGO Cars

Design and build balloon-powered LEGO cars that will blast off with the help of the air from the balloons! There are unlimited ways to build the cars and your kids will love racing them to see which one will go farther.

Balloon-Powered LEGO Cars

We just moved for the 5th time in 6 years, so most of our items are all in cardboard boxes.

I had strategically put some of my kids’ toys aside in a specially marked box. This box arguably was the most important box of all because it gave my kids something to play with right when we move into the new house.

And of course, I packed lots of LEGOs!

I am so glad I did that. You can do so much with LEGO blocks, including designing a balloon-powered LEGO car and a LEGO zip line for the minifigures!

This LEGO balloon car project is easy and simple, and it’s a fun time for the entire family! Even preschoolers can design and build their own LEGO race cars and participate in the activity. My daughter also enjoyed being the referee and watched the finish line closely to see whose car was the fastest.

Ready to race your balloon cars? HERE … WE … GO!

How to Make LEGO Balloon-Powered Cars



1. Have your child create and build his/her own LEGO car.

2. Show your child how you can build a hole to stick the balloon through.

3. Blow up the balloon and hold the end shut while you place the cars on the ground.

Balloon-Powered LEGO Cars Blow Up

4. Let the LEGO cars go and see how far the car can travel!

Balloon-Powered LEGO Cars Start

5. Measure how far the car went and record the distance in the free balloon-powered LEGO cars worksheet under “Car 1”.

6. Blow up the balloon and see how far the car can travel this time.

7. Record the result under “Distance 2” in the worksheet.

8. Make the necessary improvements and repeat steps #4-#7 with “Car 2”.

9. Tweak your LEGO car one more time and repeat steps #4-#7 with “Car 3”.

10. Determine which car has the best design and why and record your observation and reflection on the free balloon-powered LEGO cars worksheet.

Balloon-Powered LEGO Cars Race

Balloon Car Design Tips

When I first tasked my son to design his own LEGO balloon-powered car, I thought I was going to build most of the car. Surprisingly, he told me that he got this and built the race car on his own. Mommy was proud.

His LEGO car had a simple design, but there is no need for more. In fact, if you build too fancy of a car, the weight of the LEGO bricks might impede the car from going far.

We tested our designs before racing our cars. My son’s LEGO car had no issues with the air from the balloon pushing it forward. My car, on the other hand, kept flipping over instead of staying upright on its wheels.

The reason that the balloon was able to propel my son’s car without any issues is that my son’s car was low, flat, and long. Meanwhile, my car was tall and short.

Think of a race car versus an SUV. So when we apply force to the car with the air from the balloon, the air knocked my car over instead of pushing it forward.

Another design issue we noticed was that if the hole where the balloon went was too big, the balloon would fall out or change directions. To make the car go straight, we made the hole smaller. Here is a picture of what we ended up with:

Balloon-Powered LEGO Cars Design

To summarize, here are some tips for building your balloon-powered car:

  • Make sure the base of the car is wide and long enough. A short, narrow car may not be able to handle the force applied on the car from the balloon.
  • Do not build the car too tall. A lower car means the center of gravity is lower to the ground, which means the car is less likely to flip when turning at high speeds.
  • The hole for the balloon should be as small as possible so the balloon doesn’t fly out when released.

If your LEGO balloon car is not working, be patient and try again! It may take a few tries. My first attempt certainly did not work!

I changed my car design to imitate my son’s LEGO car and we were ready to go.


The Science Behind Balloon-Powered LEGO Cars

While you can do this activity just for fun, there is an opportunity to teach your child the physics of force and motion!

Newton’s first law states that “every object will remain at rest or in uniform motion in a straight line unless compelled to change its state by the action of an external force.” 

Show your child how the LEGO car by itself will not do anything. It’s not until you release the air from the balloon and apply external force on the car that it starts to move. 

For elementary school kids, you can also start explaining the concept of friction to them. According to Newton’s first law, the balloon car should continue moving at a constant speed in a straight line. However, the force of friction between the wheels and the floor slows down the car and causes it to come to a stop.

Here are some experiments you can do with your child:

  • Blow up the balloon bigger. Does the car go faster? Farther?
  • Add some more LEGO bricks to the car. How does the extra weight impact how far the car can travel?
  • Try racing the cars on a different surface (i.e. carpet vs. wood floor). 
  • Place the balloon higher up or lower down on the LEGO car. How does the placement of the balloon impact how the car moves?

Final Thoughts on the Balloon LEGO Car Activity

If your kid is not into LEGO yet, this is a great activity to get him/her interested. You can do this over and over again with different car designs. Let your kid’s imagination run wild when building the cars and take lots of pictures to document his/her creativity. You can even try different types of balloons!

This balloon-powered LEGO car activity is also awesome for playdates. I bet the kids would have a blast racing their cars with their friends!

This balloon-powered LEGO car activity is part of the 30-day LEGO STEM challenge. Download the free LEGO challenge calendar for a month of LEGO STEM fun.

YOU MAY ALSO LIKE: Free Printable 30-Day LEGO STEM Challenge Calendar

Want this activity in an easy-to-print file? I have compiled 5 super fun LEGO STEM activities for kids in a printable PDF.

Each activity includes a list of supplies, step-by-step directions, an explanation of the science behind the activity, and different extensions based on the science concepts.

The ebook includes:

  • Balloon-Powered LEGO Cars
  • LEGO Zip Line
  • Penny LEGO Boat Challenge
  • LEGO Volcano
  • LEGO Plinko Board

Balloon-Powered LEGO Cars Pin

45 thoughts on “How to Build Balloon-Powered LEGO Cars”

  1. Fun idea, thanks for sharing. Any chance you can include a picture of the “hole” for the balloon- without a balloon in it? How large is it? We can’t see it in the pictures 😉

    1. Hi Shana,
      I am working on creating cards (kind of like recipe cards) so you can print all the materials and instructions without the ads. Meanwhile, I will email you a copy! Look for me in your inbox 🙂

      1. Betty,
        If possible I would love a copy of the instructions without the ads. I am a Kinderbridge teacher next week our theme is transportation. I would love to send this activity to my parents.

          1. I also would love this activity without the ads. I would like to share with my first graders. Thanks!

  2. I love this idea. My son and family are moving from another state and will be staying with us a few weeks. I’d love to print this. Is there a way to print it without all the ads.
    Thank you for sharing this idea.

        1. Hi! I made it so you can print now without ads. Scroll to almost the bottom of the post before the comment box – Let me know if you can’t find it!

          1. Hi Susan! Sorry I used to have a plug-in that allowed me to let people print but that kept giving me errors and Google was not happy with it. I decided to combine 5 of the LEGO activities into one eBook. I would love to give it to you for free, but it cost money to have an online store and it’s expensive to maintain a blog. I would love your support so I can continue to help parents/grandparents and educators with educational and fun activities!

      1. I would love to get these Lego car ideas for when my grandsons visit or to be able to share with them during this isolation. Is there anyway you could get them to me as well since I See youve Ben able to do for others? Thank you in advance

        1. Hi Elain! I am sorry I used to send the printout manually but it got really tedious and I can’t continue doing it individually. I tried to use a plug-in so that everyone can print but that was giving me errors on my website. So I ended up combining 5 of the LEGO activities into an eBook and you can find the button to purchase it above. I would love to give it to you for free, but it cost money to have an online store and it’s expensive to maintain a blog. I would love your support so I can continue to help parents/grandparents and educators with educational and fun activities!

  3. This is a very good early STEM experience. The child can themselves produce a design and build, immediately test it, observe the result, and vary the build. Thank you for sharing!

  4. This is fun, but the lego that holds my son’s balloon keeps popping off and when it stays on, the car doesn’t move.

    1. Hi Kari,
      As I mentioned, my initial design didn’t work. Try making your LEGO car longer and light weight. It could be too heavy with too many LEGO bricks. You can hold the part where it holds the balloon in place with your hands and let go with you let go of the balloon, that might help it stay in place. Or you can put on a few more LEGOs to hold the balloon hole down. We had to play with the design to make it work and learned a lot while experimenting – part of the learning experience!

  5. I am a 76 year old kid. My plans now are to order some LEGOs and balloons from Amazon. We live in an RV and there is a long central hall that will be the perfect raceway! Ha Ha Ha

    1. Hi Emma,

      Please see the comment above – I am sorry to say I am no longer individually mailing the post. I have compiled this activity and other LEGO activities together in an easy-to-read ebook for you to use for your kids!

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top