ramblings of an electronic engineer.

7 Eleven BYO Cup Day 2012


Each year 7 Eleven has a special day where you can fill up a cup with slurpee mixture for $2.90 and this year that date is today. But before you go searching for the biggest vessel you can find here are some thing to note.

  • The cup must me water tight
  • The cup must be clean and safe to consume from.
  • The cup must be no larger then 23cm (width) x 26cm (height)

So currently I have three candidates for cup from myself, a 4 litre ice cream can, a celebrations (chocolate) box and a glass jar (complete with cork). By far the glass jar is my favourite choice (and it fits within the size restrictions, just) however measuring all sort of things around the house got be thinking. What is the maximum amount of slurpee you can get?

The Maths

Ok so first we need to calculate the amount of volume the ideal vessel can hold. The size dimensions are 23cm wide and 26cm high however we aren’t told if the width is the diameter of a circular base, width of a square base or the hypotenuse of a square base. From the promo video (above) we see that the hole each cup has to pass through is round so we will run with that.

max volume = pi*r^2*h

max volume = pi*0.115^2*0.26

max volume = 0.0108 cubic meters

Now we know that there are 1000 litres of water in a cubic meter so…

max litres = 1000*0.0108

max litres = 10.8 litres


So there you go, the maximum amount you can hope to get 10.8 litres of slurpee mixture which works out to be about 27c per litre. If you can get an optimum square container passed it work out to be about an extra 3 litres you can fit in but it’s up to each 7 Eleven employee to allow your container. So in light of that here are my three tips for BYO cup day.

Find the biggest cup you can, that fulfils the previous conditions.

It just makes sense, the lager the cup the more value for money you get. For my cups I’ve found, each only hold about 4 litres but that’s still not that bad. If you can’t find a cup I have a couple of friends that are going to try to use a family sized KFC bucket so you can give that a try.

Think about how your going to store it

Depending on how thirsty you are (and how many friends claim a share to your spoils) you should probably think about how you are going to store the remains of what you cannot finish. Here I’d recommend freezing it and cutting off pieces to either enjoy as an ice block or crush up with an smoothie maker or similar to try to make a slurpee consistency. What ever you do it’s doubtful you’ll get it to the same texture as you bought it for reason i’ve mentioned before.

Don’t worry if you miss out.

There will be plenty of other opportunities in the following years to get free slurpees and other promotions on 7/11 day, 7/11 $1 Day etc… Not convinced? I find it can be helpful to realise how fortunate we are in Australia. Many (>90%) of the word will never see/know what a slurpee is, so if you miss out on the opportunity to get one for better than normal value  no it’s not the end of the world.


4 thoughts on “7 Eleven BYO Cup Day 2012

  1. Share some with me? 😛

  2. Pingback: 7 Eleven Bottomless Cup Day 2013 | 19hertz

  3. Pingback: 100 Posts | 19hertz

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