In short
- A hay storage space calculator for a horse barn turns herd size, months stored and bale size into bales, tons and square feet of floor.
- Extension guidance: horses eat about 2% of body weight in hay a day, and 2 to 2.5% with free access.
- University of Missouri Extension allows 250 cubic feet per ton of small square bales when sizing a hay barn.
- Enter your own bale weight and size: bales vary a lot, and so does the floor they need.
On this page
This hay storage space calculator for a horse barn answers a question that comes before the slab is poured: how many square feet of floor do you need to hold a season of hay? It uses extension feeding and storage figures plus your own bale numbers. It is a planning estimate, not a quote.
En español: Calculadora de espacio para almacenar heno en un establo
| Your numbers | Result |
|---|
What this leaves out
- Aisles, doors, a loading area and room to turn a tractor or cart.
- Roof height, stack stability and how hay is rotated, oldest first.
- Fire separation from the stalls and local code requirements.
- Pasture, price and the extra hay a bad growing year may force you to buy.
A planning estimate, not a quote. Independent local builders can give a written quote through the form on this page.
How the math works
- Hay fed per day.
Horses x average weight x the share of body weight. Four 1,000 lb horses at 2% eat 80 lb a day.
- Hay to buy.
Hay per day x days stored, then divided by (1 minus the waste share) so the waste is bought too. Six months at 80 lb a day and 5% waste is about 15,158 lb, or 7.6 tons.
- Bales.
Hay to buy divided by one bale's weight, rounded up. At 50 lb that is 304 bales.
- Floor, from your bale size.
Bales divided by stack height gives the number of stacks. Each stack covers length x width. At 36 x 18 inches, 4 high, that is 76 stacks of 4.5 sq ft, or 342 sq ft.
- Floor, from the extension rule.
Tons x 250 cubic feet, divided by your stack height in feet. It allows for loose stacking and air gaps. Here it gives about 407 sq ft. The result shows both as a range.
How much space a ton of hay takes
These are the extension figures behind the calculator, and the rule of thumb for round bales if you buy those.
| Source figure | Bale type | Space |
|---|---|---|
| University of Missouri Extension | Small square | 250 cu ft per ton |
| University of Missouri Extension | Large round | 310 cu ft per ton |
| Extension horse facilities page | Baled hay | 250 cu ft per ton |
Check your own bales. The extension figure is a rule of thumb. Your result also shows the floor your actual bale size needs. If the two ranges differ a lot, weigh and measure a few bales before anyone draws a hay room.
Where should the hay go?
Many safety sources advise keeping bulk hay out of the stall building where practical, because hay is a fire load. A separate hay shed or a fire-separated room is common, and local code decides what applies to your barn. Read our guides to stall size and barn layout and horse barn fire safety in Marion County before you place the hay room.
University of Missouri Extension also advises ridge and eave ventilation in a hay barn to remove moisture given off by the hay, and a minimum 16 ft of eave height clearance for hay barns. See barn design for the Florida climate for how humidity changes the plan.
Questions to ask a builder about hay storage
- Where is the hay room, and how is it separated from the stalls?
- What clear height will the room have under the trusses?
- Can a truck or trailer unload hay close to the door?
- How does the floor stay dry in Florida rain and humidity?
- Can the hay area be enlarged later if the herd grows?
What the estimate leaves out
- Waste by storage method. Penn State Extension reports storage losses of 2 to 40% depending on how bales are stored. The waste input above covers feeding waste only.
- Different hay. Round bales, large squares and cubes need other numbers. Enter your own bale size, or use the 310 cubic feet per ton figure for rounds.
- Buying in loads. Many buyers fill the room once or twice a year, so check the first number against the amount you can store at one time.
For the other side of the feed room, the horse manure storage bin size calculator sizes the manure bin.
To compare hay with grazing, use our hay calculator for horses and the pasture acreage calculator. When you are ready to plan the building, use the form on this page to ask independent local barn builders for a written quote, and read how to choose a horse barn builder first.
Sources
- Using hay in horse diets, University of Minnesota Extension: 1% minimum, about 2%, 2 to 2.5% with free access.
- Buying winter hay for horses, Penn State Extension: waste by feeder type for small square bales, storage losses of 2 to 40%.
- Sizing and siting hay barns, University of Missouri Extension: 250 cubic feet per ton of small square bales, 310 for large round, 16 ft eave clearance, ridge and eave ventilation, stacking usually 3 to 4 high.
- How much storage area is required for hay?, Extension Horses (eXtension): about 250 cubic feet per ton of baled hay.
Frequently asked questions
How much space does a ton of hay take?
University of Missouri Extension says to allow 250 cubic feet of storage per ton of small square bales and 310 cubic feet per ton of large round bales, which are less dense. Another extension horse-facilities page also gives about 250 cubic feet per ton of baled hay. Your own bales may be denser or looser, so the calculator also works from the size you enter.
How much hay does a horse eat in a day?
University of Minnesota Extension says horses need at least 1% of body weight in roughage daily, most should eat about 2% in hay, and horses with free access will willingly eat 2 to 2.5%. For a 1,000 lb horse, about 2% is 20 lb a day before waste.
How high can hay bales be stacked?
University of Missouri Extension says to stack as many bales as the equipment and bales will safely allow, usually 3 to 4 high. The real limit depends on the bale type, how stable the stack is, your equipment and the clear height under the roof, so ask your builder what height the hay room will have.
Should hay be stored inside the horse barn?
Many safety sources advise keeping bulk hay out of the stall building where practical, because hay is a fire load. A separate hay shed or a fire-separated room is common. Confirm what applies to your barn with Marion County and your builder.