Turning the bale is worth less than people expect, and sometimes worth nothing
Take a 36 by 24 ft bay with six inches left at each wall, so the stack sits on 35 by 23 feet. Small squares at 3 ft long, 18 inches wide and 15 inches high go in eleven along the length and fifteen across, which is 165 to a layer, leaving 2 ft over lengthwise and 6 inches across. Turn every bale ninety degrees and you fit twenty-three along the length and seven across, which is 161. The first way wins by four bales a layer.
Four bales in 165 is under three percent, and across twelve layers it is 48 bales out of 1,980. That is worth knowing and it is not worth reorganising a stacking crew over. What decides it is not the bale and not the bay, it is which leftover strip ends up wider — 2 ft and 6 in one way, 6 in and 2 ft the other, which is why the two came out so close here. Take two feet off the bay width, to 36 by 22, and it flips: lengthwise drops to 154 a layer while turned stays at 161.
The calculator prints both orientations and the leftover in each direction so the comparison is visible rather than asserted. It does not recommend one, because for any given bay the winner depends on numbers you entered and there is no general rule to state.
Pounds per square foot is height times density, and that is the whole formula
The 1,980 bales above at 55 lb each weigh 108,900 lb sitting on 805 square feet, which is 135.3 lb per square foot. Each layer contributes 11.27 lb per square foot, so the loading scales straight with the stack height.
For bulk material the arithmetic is even shorter: pounds per square foot equals the depth in feet times the density in pounds per cubic foot. Sixteen feet of something at 11 lb per cubic foot is 176 lb per square foot, and it does not matter what the material is or how big the bay is. That is why the page reports the figure per foot of depth as well as the total.
| Stack height | Layers of 15 in bales | Bales in a 35 x 23 ft bay | Floor loading |
|---|---|---|---|
| 5 ft | 4 | 660 | 45.1 lb/sq ft |
| 10 ft | 8 | 1,320 | 90.2 lb/sq ft |
| 16 ft | 12 | 1,980 | 135.3 lb/sq ft |
| 24 ft | 19 | 3,135 | 214.2 lb/sq ft |
What the page will not do is tell you whether any of those numbers is acceptable. If you enter the floor capacity figure you were given, it appears alongside as your own number, labelled as reported, and the calculator works out the layer count at which the arithmetic reaches it. That is division, not a verdict. Whether a slab on grade, a gravel pad or a suspended mow floor can carry a given loading is a question for whoever designed it, and the three cases are not remotely alike.
Weigh the bales, because the number on the invoice is not it
Small square bale weight ranges enormously with crop, moisture and how hard the baler was set — the same machine on the same field turns out bales that differ by a third across a season. Round bales vary less in dimension and more in density, because the core is packed differently from the outside. Every tonnage figure on this page is your bale weight multiplied by a count, so an error in the weight is an error of the same percentage in the tons and in the floor loading.
The cheapest fix is a bathroom scale and five bales off the top of the load. If you are buying by the ton, this is worth doing anyway. For the other direction of the question — how many bales a given number of animals will eat over a given number of days, and the stack that quantity makes — the hay and feed storage calculator starts from the ration instead of from the building.
A rectangle is optimistic
The calculator fills the bay as a solid rectangle to the height you set. Real stacks are not rectangles. They step back as they rise so they do not topple, they lose the top courses where a gable roof slopes in over the walls, they leave an aisle wherever the loader has to reach, and the bottom course usually sits on pallets or on a layer that is written off to floor damp. Every one of those makes the real capacity lower than the figure here, and none of them are modelled.
Treat the output as the ceiling and take a working figure below it. The manure storage pad calculator handles the opposite case — a free pile with a repose angle rather than material between walls — and the material storage space calculator does sheet goods and board stock in a shop. The building the bay sits in is laid out by the post-frame bay layout calculator.
Questions people ask
Does the calculator say whether my floor can take the load?
No, deliberately and permanently. It reports pounds per square foot, which is weight divided by footprint, and if you enter the floor capacity figure you were given it restates that beside it as your own number. It does not compare them and it does not draw a conclusion. Floor capacity is not one number: a slab on compacted grade, a slab over poor fill, a gravel pad and a timber mow floor behave in completely different ways under the same loading, and point loads from a loader wheel matter more than the spread load from the stack. That question belongs to the engineer or the slab designer, and no arrangement of these figures replaces one.
Which way round should I stack the bales?
Whichever the calculator shows fits more, for the bay you actually measured — and be prepared for the answer to be that it barely matters. On the default numbers one orientation gains four bales a layer out of 165, under three percent. The winner is decided by which leftover strip comes out wider, so it flips with small changes in bay size and it cannot be predicted from the bale dimensions alone. Handling usually decides it in practice: bales stack more stably with the strings running a particular way, and that consideration outweighs three percent of capacity.
Why does the answer come out lower than my barn actually holds?
Usually because the usable height field is being read as the eave height. The stack cannot go to the eave on a sidewall and it certainly cannot go to the eave under a sloping roof, so the figure to enter is the height you will actually stack to, less any headroom you want kept clear. The other common cause is the reverse — the calculator reading higher than reality, because it fills the bay as a solid rectangle with no step-back, no aisle and no allowance for the roof slope cutting into the top courses. Treat the number as the ceiling.
What does bulk mode do differently?
It drops the bale geometry entirely and fills the bay level to the height you set at whatever density you enter, which is the right model for material held between walls — grain, chips, sand, compost in a bunker. Pounds per square foot in that case is just depth times density, so sixteen feet at 11 lb per cubic foot is 176 lb per square foot regardless of the bay size. It is the wrong model for a free-standing pile, which takes a repose angle and comes out as a prism capped by cones rather than a box; the manure storage pad calculator on this site handles that shape.
Should I subtract anything for pallets or dunnage under the stack?
The calculator does not, so subtract it from the usable height yourself. Four inches of pallet under a stack costs you nothing at all if the layer count does not change and costs you a whole layer if it does, which is exactly the kind of threshold that is easier to see by trying two numbers than by reasoning about. The wall clearance field works the same way: six inches at each wall costs a foot of length and a foot of width, which on the default bay is the difference between eleven bales along the length and twelve.