Looking to plan a late summer 5 day ish trip and trying to work out how much meths to carry. Cooking roughly -

Breakfast - porridge and decent cup of tea
Dinner - 500ml ish of water to rehydrate something

maybe the odd cuppa here and there

About 400ml ... I'm working on 80ml a day which should be ample.

Depends how much your stove uses to boil 500ml of water (indoor tests very misleading). For me, that would be 20+20+20+ spare 20-40mls depending on extra drinks, per day.

I'd probably stash 2x 250ml bottles within my framebag for such a trip.

500ml should be plenty. You'll tend to find eating rehydrated meals gets a bit tiresome at times so you'll make the most of any cafe stops.This which will cut down on the amount of cooking you may end up doing so you'll end up using less than you thought

Cheers. I was looking at them trangia bottles which shoould be tough enough to fit in a monkii cage rather than have to pack away. I could get a 500, or a 300 (and maybe stash an emergency 100 in a small bottle)

Cafe's only tend to yeild chips and coffee for me rather than meals

I like to carry 2 bottles on multiday rides in case of leaks, spills, etc

I'd carry 500ml for five days but my stove burns really hot and I tend to stop in idyllic places and celebrate the scenery with a cup of tea.