Rows of hay bales stacked under a barn roof, out of the weather

How much hay do I need for winter?

Bymuntaseer

For one 1,100 lb horse through a 150-day winter averaging 20 °F overnight: about 5,444 lb (2,469 kg), or 109 bales of 50 lb small squares.

Then buy more than that. Not as a safety margin — because a stack of hay does not weigh in January what it weighed in September, and almost nobody counts that.

How much hay do I need for winter, by number of horses

A 150-day winter averaging 20 °F overnight, 1,100 lb horses at maintenance, 50 lb small square bales
Hay for the season Bales Per month
One horse 5,444 lb (2,469 kg) 109 bales 22 bales
Two horses 10,887 lb (4,938 kg) 218 bales 44 bales
Three horses 16,331 lb (7,408 kg) 327 bales 65 bales

Two things set these figures more than anything else. The first is bale weight: everything scales directly off it, and bales sold as fifty-pounders run 40 to 80 lb. The second is how cold it actually gets where you are, which is covered in full in how much hay a horse eats in the winter.

The part everyone forgets: what the stack loses

Hay keeps respiring after it is baled. Microbes work, moisture moves, and dry matter leaves as carbon dioxide, water and heat. How much leaves depends almost entirely on where you put it.

Dry matter lost in storage, and what that does to the 109 bales one horse needs for the season
Stored DM lost, up to 9 months Bales to actually buy
Enclosed barn 0–2% 109–112
Under a roof, open sided 2–5% 112–115
On pallets, covered 2–4% 112–114
On the ground, covered 5–10% 115–122
On pallets, uncovered 3–15% 113–129
On the ground, uncovered 5–20% 115–137

Read the last two rows against the first. The same winter’s hay is 112 bales in a barn and up to 137 bales if it sits on bare ground under the sky. Pallets and a tarp are the cheapest hay you will ever buy.

Quality drifts as well as quantity. Crude protein falls about a quarter of a percentage point a month in storage, and fibre climbs — so hay that was adequate in October is a slightly poorer feed by March, at exactly the point in the year the horse needs it most.

How much hay does a horse eat a year?

With no grazing at all, 9,392 lb (4,260 kg) — 188 bales. That is the number for a horse in a dry lot year round.

Most horses do not live like that. If yours grazes through the summer, hay is a winter and shoulder-season cost, and the useful figure is the one at the top of this page rather than the annual one. The annual number is mainly useful for budgeting, and for realising how large a line item hay is.

Buying: when, and how much at once

Hay is cheapest out of the field and dearest in late winter, which is exactly when people who under-bought go looking for it. Buying the season in one go is nearly always the better trade — provided the storage is there.

  1. Weigh a bale from the load before you agree a price. You are buying weight, not bales, and the difference between a 40 lb and a 60 lb bale at the same price per bale is a third of your money.
  2. Buy by the short ton where you can. It removes the bale-weight problem entirely.
  3. Add the storage loss on top using the table above, not a round guess.
  4. Then add a fortnight. Winters run long, and running out in February means buying at February’s price from a position of weakness.

How much hay to store for winter, and how to store it

In order of what actually matters:

  • Off the ground. Pallets, gravel, anything that breaks the wicking path and lets air move underneath. This is the single biggest lever in the table.
  • Under cover. A roof beats a tarp, a tarp beats nothing.
  • Air around it. Stacked tight against a wall in a damp barn is how good hay goes musty.
  • Cured properly before it is stacked. Hay is about 90% dry matter when it is right. Baled wetter than that, it will heat.

Hay that heats: the risk nobody mentions

A stack of damp hay generates its own heat, and it does not stop on its own. This is a genuine cause of barn fires, and it is seasonal — it happens in the weeks after hay comes in.

What the temperature in a hay stack means — Mississippi State’s monitoring guidance
Stack temperature What to do
Below 130 °F Monitor temperatures in the hay stack twice a day.
130–150 °F Temperature may fluctuate. Check temperature every few hours.
150–175 °F Temperature will most likely increase; move hay out of the barn to provide air circulation and cooling. Monitor temperature every 2 hours.
Above 175 °F Fire is imminent or present. Contact the fire department immediately. Do not attempt to put out any fire or move the hay.

Most of the change happens in the first twelve days after stacking, so that is when to pay attention. A long probe thermometer costs very little against a barn.

The short version

Work out the season’s weight, convert it to bales at your bale weight, add the storage loss for how you will actually store it, and buy it in autumn. For one horse and a 150-day winter that is 109 bales fed, and 122 bought if it is going on the ground under a tarp.

Mild weather, for comparison, is only 25.7 lb (11.7 kg) a day against 36.3 lb (16.5 kg) in the cold. The winter is not a small adjustment to the year — it is most of the hay bill.

Common questions about buying and storing winter hay

How many bales of hay per horse per month?

About 16 bales of 50 lb small squares in mild weather, and closer to 22 a month through a cold winter. Both figures move directly with bale weight, so weigh one of yours before ordering.

Is it cheaper to buy hay for the whole winter at once?

Usually, yes — hay bought in autumn out of the field is close to its cheapest, and hay bought in February is bought from someone who knows you have run out. The catch is that the saving is only real if you can store it properly. Bought cheap and stacked on bare ground uncovered, you can lose 5–20% of the dry matter and hand the saving back.

How long can hay be stored?

Well over a year if it is dry, off the ground and under cover — a barn holds losses to 2–5% even at 12 to 18 months. Left outside on the ground, the same period runs 20–35%. Quality falls too: crude protein drops by about a quarter of a percentage point a month.

How much hay do I need for winter for 2 horses?

10,887 lb (4,938 kg) across a 150-day winter at 20 °F — 218 bales. Two horses is not quite double one, because bale counts round up, and it is worth buying to the round number above rather than below.

Can stored hay catch fire?

Yes, and it is the reason hay must be properly cured before it is stacked. Hay baled damp heats as microbes work, and above 175 °F Mississippi State’s guidance is to call the fire department rather than move the bales. Monitor a new stack for the first few weeks — most of the change happens in the first twelve days.

Related calculators and guides

Where these figures come from

Every figure on this page is published and cited. Where sources disagree we take the more conservative one and say so. Our full approach is set out in how we source our numbers.