Depends on the horse. I would have said 3 acres for a horse and companion but D could manage with much less as she is on restricted grazing for 8 months of the year anyway. Think about how much space you would like to see two horses stood in and then double it so that you can rotate your fields.
BHS say that to keep a horse out 24/7 all year round without needing to feed extra hay you need 1.5 acres for the first horse and 1 acre per horse after that.
But it can be done on far less if you bring horses in at night in winter, restrict access in wet weather (ie don't turn out at all), feed hay in winter, have a 'trash paddock' sectioned off for winter etc.
When I kept my horse in a inner city farm, we had two fields, one of just under an acre and the other about half an acre. We kept 3 horses and one pony plus a couple of sheep on this much land by careful grazing management and feeding extra hay in winter.
I have two horses at the moment on two fields totalling approx two acres...before that I had one horse on almost 6 acres...what i did, was kept the horse on two fields, and let local farmer have rest, he then kept my two fields in good shape, ie sprayed weeds etc...i also used electric fencing and strip grazed field, and poo picked every two days. My farmer also slurried fields in order, meant I always had good grass..topping grass is also good idea, as horses are extremely picky. Most farmers are very happy to help you keep your grass in good order...as weeds are very quick to spread to adjoining fields..also there is nothing better than a couple of drying-off cows to clean up your fields. They leave them in a lovely healthy state. One thing I always do, is when I worm my gee gees, is keep them in for a couple of days, better worms in stable than on grass. Good luck
I keep two horses (one good doer and one older needing more nosh). I have them on a piece of land that is about 1500 sq m (hang on I'll find a conversion chart, ah about 1/3 of an acre). This is divided in half and is pretty ropey grass. So, they spend the night in the stable, have a hard feed and plenty of hay for breakfast, then they go out in their paddock for the day. At about 2pm they get another pile of hay and then at 8pm it's back in for another hard feed and hay for the night.
Now, this is not ideal but is luxury compared to what they had before. They have room to run about and be silly but they have to work very hard for their grass and I have to feed hay and feed 365 days a year. I also have to poo pick religiously.
It depends on the land! What sort of soil, how it drains, quality of pasture etc. I've struggled with 5 on 15 acres on horrible wet clay soil, and managed 3 easily living out 24/7 on 3 acres. There can be no hard and fast rule on this one, whatever the BHS say.
I see many horses kept in paddocks of an acre, or less, all year round. Generally two or three horses.
They have sheds/barns, and feeders full of hay through out the year. Whilst this may not be what is generally recommended none look anything less than healthy and content with their lot.
Depending on your soil, it can be done, just don't expect what grass that grows to support anything less than a pony without supplemental feeding.
i have 3 horses.16.1,15hh and a minature on 2 acres.they come in at night all year and have hay when needed and i use one paddock to trash over winter,then allow to recover and strip graze in summer so they have nice grass all year.its doable but pooh picking and field maintenance is important.my girls look fab on it.
I have 3 horses on 2 acres, 1 on just less than 1 acre, 1 + foal on half an acre. None are dying of starvation, all are quite happy.
All are fed hay most of the year because my land is better served growing hay to feed them than putting them out on it to founder and still have to buy hay for the 7 grassless months of the year I get.
Each to their own. It suits me to keep my horses like this at this moment in time, and three years ago it would have horrified me, it doesn't now. In the UK it was different they'd be up to their knees in a rice paddy in winter and NEED about 2 acres per horse to have any chance of having a tiny patch of unpoached land.