Rabbit age/weight

Question
I have a 7mth old Black Otter Mini Rex rabbit named Bandit. We got him at ~10wks old from pet shop thinking he was a dwarf (and also a she, lol). He is already bigger and heavier than my 2yr old Netherland Dwarf rabbit named Dart. He was neutered at 4mths (when Vet informed us she was a he). Wondering how big he is likely to get? He is 2.5lbs atm. We will be upgrading his cage soon and want to make sure the next one will last him hopefully years.

I would appreciate any info you can provide on how old he will be when he stops growing and ideal weight for him to be then.

Answer
Hi Kevin

Sorry for the delay in reply.

From a pet shop he may well be a rex cross, or a Standard Rex who get around 2kg - 2.5kg (4lbs). I was trying to find a photo of the Standard/Mini Rex pair at the rescue I volunteer at, this was the best I could find as they don't hold still, the size ear difference is significant enough to show haha! Stilton, the standard Rex on the left, has a tear duct problem hence the wonky looking eye.
https://igcdn-photos-a-a.akamaihd.net/hphotos-ak-xfp1/t51.2885-15/10755733_734883849937624_1550226205_n.jpg

For final adult size don't rely on breed standard, especially for a pet shop bun as they are likely to have a cross in them. Decide healthy weight by body condition. You can work out if a bun is under or overweight by the handy guide here:
http://www.therabbithouse.com/diet/rabbit-weight.asp

For caging, I don't recommend rabbits are caged full stop really. It's an old fashioned idea. Really they need the same kind of housing and freedom as you would offer a house cat, but with plenty of bunny proofing! If you need to enclose them when you're not home to supervise, something like this is more up to date (Facebook image sorry!):
https://scontent-lhr.xx.fbcdn.net/hphotos-xaf1/v/t1.0-9/1505135_570120936406637_781571025_n.jpg?oh=10f7a6b1fd76010e27c50876dfd2de84&oe=55A21071
Or this:
http://www.manorpethousing.co.uk/images/imagegallery/original/94.jpg
Or just let them have a spare bedroom!
http://www.manorpethousing.co.uk/images/imagegallery/original/28.jpg

I hope I've helped!
Cat