Recommend a large (>25 litres) Children's Backpack/Rucksack for my 12 year old to use as school bag

[BuzzLife]

it's for a girl but she's more likely to go for a boys than an overly girly one.
It needs to be >25 litres as she wants to fit her pe kit in the bag as well.
It's a bit painful searching in Amazon as you can't filter by capacity, most bags don't even include capacity in description, just the dimensions.
I have discovered that if you put the dimensions in Google it will give you the capacity, ie 30cm 16cm 42cm returns 20.16 litres. Also works for inches.
Thanks

I would say at age 12 your dd will need something significantly larger than 25 litres - probably look at about 40 litres or so.

Jansport backpacks are very good quality, DD2 who is now 14 has been using hers for school everyday since age 7 and it comes on holidays with us too. Wide variety of styles and colours available in sport shops and school uniform suppliers. Used by both boys and girls so she should have no trouble choosing one to suit. The "Galaxy" and "Scattered Stars" prints may appeal to her. DH has my old one now, it's on the go for more than 25 years!

DD1 has a SportHouse bag which is similar in quality to Jansport. It's on the go for 3.5 years now.

DS (15) has this bag from Amazon. It's big enough for everything he needs and looks great, really comfy straps too.

Also, just be wary of using dimension to calculate capacity, the dimensions shown will be the measurements on the bag at the maximum height, width, depth of the bag but vey few backpacks would be the same size all over in the way that a suitcase would. So your bottle holder pocket and carrying handle may add 3 inches that exists only on the outside of the bag.

Got DS1's from Mountain Warehouse in the sale.