The largest size insulated food jar from Lunchbots has had a design overhaul to match the design of the two smaller food jars. These food jars were the first in our store to have a completely stainless steel interior. Klean Kanteen also used to do it a long time ago, but  they changed the design and now there's plastic on the inside of the lid. Thermos have always had plastic on the inside of the lids of their insulated food jar. We expect more brands will follow suit, like Avanti have done, but Lunchbots were the first.

Which size should I choose?

Now that they're all the same design, the first thing you need to understand about anything that's vacuum insulated is that is works better when it's completely full.  Work out how much you want to put it and buy to that. If you buy a 470ml food jar and only half fill it, your insulation time will be reduced. You would be better off with the 235ml.

Are little hands going to have to open it? Then choose either the 235ml or the 350ml as they share the smaller diameter.

Compare the sizes

  • 235ml (8oz) - 8.95cm in diameter x 10.8cm tall and is represented by the PINK flask in the photos below
  • 350ml (12oz) - 8.95cm in diameter x 12.7cm tall and is represented by the GREEN flask in the photos below
  • 470ml (16oz) - 11.43cm in diameter x 11.43cm tall and is represented by the BLUE flask in the photos below

How long do they insulate for?

All three sizes are rated to insulated hot food up to 5 hours and cold food for up to 10 hours.

How do I get the best insulation out of these insulated food jars?

To get the best hot insulation out of any insulated container, pre-heat it with boiling water for 5 minutes and then tip it out and add your hot food. If you put hot food in a cold container, the temperature drops a little instantly. If you fill the container, you'll get better insulation. At the end of your insulation period, the food should still be a minimum of 50% of its original temperature, so it will be warm, but not as hot as when it went in.

If you don't pre-heat or if you don't fill it, or you put food in that isn't pretty much being held together by liquid, your insulation period will not be as long. It is important to remember that the lids are not insulated. Whether you're talking about one of these or a thermos flask, the lids are never insulated.  You can give yourself a little boost in colder climates by putting your food jar in an insulated lunch bag to keep the external temperature at bay a little. In summer, you can use it with an ice pack and your regular lunch box.