How Big is your Child’s Bladder?

optimism-619018_1920 PixabayAs the founder of Brolly Sheets – I talk to hundreds of parents every year about bed wetting and potty training.  Our Brolly Sheets themselves hold 2 litres of wee – but I am often asked if this is enough.  (Stop and think how much 2 litres is – it is a lot!)

2 litre absorbency is plenty for children and for adults.  The reason our Brolly Sheets are so absorbent is that we also sell them for adults.  In our early days of testing – we use to wee in a jug and measure (what you do when you start a business!!) but I have since found out that math can solve this for us.

Interestingly, some of the most easy to understand information about how a normal bladder works came from the Multiple Sclerosis Trust.  This is not necessarily a site you would have visited but it’s a great explanation.

Basically a normal adult bladder hold 300-500mls of fluid (that’s about half a pint to a pint) and we typically empty our bladders between 6 and 8 times a day.

Children are of course smaller and with all their activity they can sweat out quite a lot of fluid in a day – so for them the normal range for bladder emptying is between 4 and 8 times a day.

And one of the most interesting discoveries we found is that there is actually a formula for calculating your child’s approximate bladder capacity!  Here it is…

Age of child x 30 + 30 = average bladder capacity in mls

For example, for a 6 year old child you calculate it as follows:

6 x 30 + 30 = 210 mls

Calculation sourced from

Of course, this figure is an average so if your child is substantially smaller or bigger than other children their age, their bladder capacity’s likely to different too. Either way, it’s reassuring to know that our Brolly Sheets hold up to 2 litres so they’ll never let you down.

We know as a parent of a child who wets the bed it can be really hard to get some straight forward facts.  We hope this helps.  If you do notice unusual bladder capacity in your child, it’s easy to have a chat with your family doctor. But for most of you, now you know what “normal” is, you can at least put that nagging worry to rest.

Sleep easy,


Want to find out more about what a Brolly Sheet is?


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