How many helium-filled balloons do we need to lift a house like in Up?

combien de ballons remplis d'hélium faut-il pour soulever ta maison


If you have ever seen the movie Up, you probably ask yourself a very good question: how many balloons are needed to make a house fly in real life? In that animated film, Carl Fredricksen, 78 years old, is a balloon seller, and his craziest dream is to fly towards wild places in South America. He achieved his dream by tying many helium-filled balloons to his house to fly them over there. But how many balloons did he actually use?

What is helium?

un bouquet de ballons remplis d'helium

Helium is a gas. It is an element from the periodic table, and its symbol is He. Helium is the second most abundant gas in space after hydrogen (Symbol = H). It was discovered in 1869 by Jules Janssen, a French astronomer who was looking at the sun’s radiations during a total eclipse. However, it was isolated on Earth for the first time in 1895. Helium is a transparent and odourless gas that is not toxic. If you breathe it, that element can raise the pitch of your voice for a few minutes. However, you should not try that because you could suffer from a headache or feel dizzy.

An airship

It is a big balloon kept buoyant by a body of gas lighter than the air.

L'helium - gaz inerte

Helium is not only used to change your voice pitch. We also use it to blow balloons or airships. If we use helium to blow balloons, it is because that gas is lighter than the air around us. That means that helium balloons can float in the atmosphere! At a fair or in an amusement park, Mickey balloons, for example, fly thanks to helium.

un bouquet de ballons remplis d'helium

How do balloons filled with helium float in the air ?

That’s right, helium balloons float in the atmosphere! It is not as magical as you could think. Think of an empty plastic bottle with its cap on. You tie it with a piece of string, just like for a balloon. If you dive inside a pool with the bottle, it will immediately go back to the surface. If that bottle wants to rise, it is because the air inside it is lighter than the water around it. The same principle applies to helium balloons. Helium is lighter than our atmosphere (made of 80% of nitrogen, N2, and 20% of dioxygen, O2). Just like the bottle in the pool, the balloon will go as high as it can. If you let the balloon go, nothing will hold it down anymore, and it will rise until it explodes. The helium that was inside the balloon will keep going up until it reaches outer space!

ballons de fêtes remplis d'helium sur curiokids
promenades avec des ballons remplis d'helium
un bouquet de ballons remplis d'helium

Make your house fly

It is time we answer the initial question: how many balloons do we need to lift a house? The calculation is not that difficult. Just keep in mind that one litre of helium can lift one gram. That means if one litre of helium is in a balloon, it can lift one gram. Let’s say we use balloons having a diameter of 30 centimetres. Each one could contain 14 litres of helium. Each balloon could thus lift 14 grams.

Counting frame

a counting frame is a tool you can use to help calculate values. It can help you turn centimetres in metres and kilograms in grams.

So, let’s say a house weighs 70 tonnes (it heavier than five elephants together!). If you have already learnt how to use a counting frame, you will know that 70 tonnes = 70,000,000 grams (70 million grams). Since a balloon can lift 14 grams, you need to divide 70,000,000 by 14.

70 000 000 : 14 = 5 000 000

The result is 5,000,000 (5 million) balloons. You will thus need 5 million balloons to lift a house of 70 tonnes. Isn’t that a lot?

Now that you hold the key to the solution, you can have fun finding out how many balloons you need to lift anything! For example, we would need 124,447 balloons to lift Flash McQueen, the main character in Cars. If you weigh 40 kg., you would need at least 2,858 balloons! So, next time you want to travel like Carl Fredricksen, think twice… It is probably not the best means of transport, even if it could be a dream come true!

le dodo dans là-haut

Did you know?

Can helium also lift humans?

The fireproof balloon

ligne de flocons de neige graphic

An experiment proposed bu curiokids