If you want to know roughly how heavy one kilogram is, have a look in the kitchen cupboard at home and see if you can find a one-kilogram bag of sugar or flour. It will be marked 1 Kg like this. That’s the standard abbreviation for kilogram. You might be able to find a one-kilogram box of breakfast cereal. It will be quite a lot bigger than the bags of sugar or flour, and much bigger than a liter of water. That’s because cereal has quite a small mass for the space it takes up. It takes a lot of cereal to fill a one-kilogram box.

You can try some experiments at home if you like, to help you estimate mass. Hold a one-kilogram item in one hand like the flour or sugar, and then pick up some other items without looking for the weight on the packet and see if they seem heavier, lighter, or similar in weight then check the packet to see how accurate your guess was.