Nope you get your stable (the yard has verying sized stables so you get on of the appropriate size) and your field (in a group or alone depending on your requirements).
I think the only time when ''size really matters'' with livery costs are if feed/ hay is included...
We used to do DIY with stable, year round turnout, haylage, and use of the schooling field, Xc and SJs. For big horses (16h+) we charged £30/wk, medium (14.2-16h) £25/wk, and ponies (up to 14.2) £20/wk. The small ponies went in a seperate block of smaller stables, and obviously the size of the horse influenced how much haylage they ate... Didn't seem right to charge a tiny pony the same as a hunter..
We usually charge one for all but a proposed new pony (small) is apparently getting preferential rates, although will still be taking up a space, just wondered if it was a usual thing, this is diy not including hay etc.just stable and grazing. On this thinking a v large horse could be charged extra ???
Stable Board - pay the same as a horse, as someone says they are still using a stable and I still have to provide bedding, cleaning, turn in, turn out blah, blah, blah, they are paying more for the service provided than fodder.
Pasture Board - sliding scale, dependent on size, how can I charge the same board for a 13h pony as I would for an 18h Belgian or Percheron? The Drafts would eat about the same amount of hay in a day as a pony does in three! (Which is why I avoid Drafts like the plague unless someone begs me on bended knee!)
At our yard, the rent includes stable, hay and bedding if on straw. Its the same rate for all. I have actually brought this up with the YO before as i pay the same as the 16.2s and i have a 11.2 sec a who has a tendancy towards laminitis so doesnt have much hay!! Which i find madness as i use a 1/3 of what they do!!! I use shavings for this reason as its cheaper for me than paying the monthly charge of straw as hes very clean and doesnt hardly use any bedding either!!
I do DIY livery: and because they're totally responsible for supplying all own feed etc, I charge all one price whatever the size. Stable is included, but sometimes people ask if its cheaper if horse lives out all the time. Answer is no!! Coz actually it costs me as YO more if horses are out 24/7 - if they're stomping around in the wet and chamming up the field I've got to pay for more maintenance, whereas if horses are in overnight during the winter months at least the field has more of a chance.
Keep it simple I say - all one price whether shetland or shire!
One price - Works for me as I have two 13.2hs (one still growing though) and by having a flat rate means I don't get stuffed into pokey little stables (not that we have any of those on the yard!!).
Anyway, my growing one eats as much as my OH's picky 17.1h....!!