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How to Estimate Hay Yield in Bales
Manesh Jayawardhana
CIO & Co-founder
Eight and a half hectares at four tonnes a hectare is thirty-four tonnes. How many bales that is depends on a figure that varies by a third between machines and settings.
Tonnage is arithmetic. Bale count is a property of your baler, and the only reliable way to know it is to weigh some.
Yield per hectare is the estimate’s weakest input
Everything downstream depends on it, and it varies with sward composition, fertility, rainfall, cut number and season.
First cut typically yields substantially more than later cuts. A well-managed ryegrass ley outyields old permanent pasture by a wide margin. A dry season can halve a cut.
Regional averages are a starting point and your own field history is far better. Three years of records for the same field, same cut, gives an estimate worth planning against. A published average gives you an order of magnitude.
Where there is no history, the honest approach is a range rather than a figure, and planning storage and transport against the upper end.
Bale weight varies more than people expect
The conversion from tonnes to bales is where estimates go wrong, because bale weight is not a constant.
It varies with:
Format. A small square bale and a 5 ft round bale differ by more than an order of magnitude.
Density setting. The same baler on the same crop produces noticeably different weights depending on how hard it is set.
Crop type and moisture. Denser, damper material makes heavier bales.
Chamber wear, which changes achievable density over a machine’s life.
| Format | Typical weight |
|---|---|
| Small square | 15-25 kg |
| Large square (120×70) | 300-500 kg |
| Round 4 ft | 250-350 kg |
| Round 5 ft | 400-600 kg |
Those ranges are wide because they have to be. Weighing five bales from your own machine on your own crop replaces the whole table with a number you can rely on.
Moisture affects weight and safety
Hay is baled at a target moisture, and both ends of the range cause problems.
Too wet — above roughly 20% for most bale formats, and lower for large dense bales — and the hay heats as microbial activity continues. That degrades the feed, can produce mould, and in the worst case causes spontaneous combustion in stacked bales. Barn fires from hay baled too damp are a recurring and serious event.
Too dry and leaf shatter increases, particularly in legumes, where the leaf carries most of the feed value. Baling bone-dry hay loses quality in the field.
Moisture also inflates weight. Hay sold by weight at 25% moisture contains less dry matter than the same weight at 15%, which matters commercially as well as agronomically.
Monitoring stack temperature in the weeks after baling is standard practice for anything baled at the wet end, and it is worth doing rather than assuming.
Plan storage from the upper estimate
An estimate produces a range. Storage and transport should be planned against the top of it.
Running out of shed space with bales still in the field means either leaving them out, which costs quality, or arranging storage at short notice, which costs money.
Having spare space costs nothing. That asymmetry means the planning figure should be the optimistic yield, even though the budgeting figure should be the conservative one.
Common mistakes to avoid
- Using a published bale weight rather than weighing your own.
- Estimating from a regional yield average when field history exists.
- Baling above the moisture target to beat the weather.
- Stacking damp bales tightly, which concentrates the heating risk.
- Planning storage from the mid-range estimate.
How to do it with Hay Bale Yield Estimator
The Hay Bale Yield Estimator converts area to tonnage to bales.
- Enter field area and a yield per hectare from your own records where possible.
- Choose the bale format.
- Adjust the bale weight to what your machine actually produces.
- Plan storage against the upper end of the range.
Your national agricultural advisory service publishes forage guidance. Other farm tools are in the tools directory.
Frequently asked questions
Why does moisture matter?
Because it affects weight and safety. Hay baled above roughly 20% moisture heats as it ferments, spoiling the crop and, in stacked bales, occasionally causing fires. Wet weight also means less dry matter per tonne sold.
How much does a bale weigh?
It varies widely with format, density setting, crop and moisture — a 5 ft round bale might be 400 to 600 kg. Weighing a few of your own is worth more than any published figure.
How accurate is a yield estimate?
Only as good as the yield per hectare assumption, which varies with sward, season and cut number. Your own field history beats a regional average substantially.
Final thought
Weigh five bales and write the number down. It converts every future tonnage estimate into a bale count you can trust, and it takes one afternoon.