Hay Moisture Calculator
Convert as-fed hay to dry matter at any moisture, and see what the water in a load is costing you.
Your numbers
1,100 lb as fed at 15% moisture (85% dry matter)
935 lb dry matter
- Water in this hay
- 165 lb
- As-fed lb to deliver the target DM
- 35.3 lb
- Price per ton of dry matter
- $165
- You are paying about $21 a ton for water — competing hay at 12% moisture is the same value at $145 a ton.
- At 15% this hay is within the 18% safe baling moisture for this package and should cure in the stack without heating.
- Cattle eat to a dry matter requirement, so wetter hay means more pounds fed per head per day for the same nutrition.
Show the math
- Dry matter percentage100% − 15% moisture = 85% dry matter
- Dry matter in the hay1,100 lb × 85% = 935 lb DM
- Water carried1,100 − 935 = 165 lb of water
- As-fed needed for the ration30.0 lb DM ÷ 85% = 35.3 lb as fed
- Price on a dry matter basis$140/ton ÷ 85% = $165/ton DM
- Equivalent price at 12% moisture$165 × 88% = $145/ton
Assumptions this calculator used
Nothing here is hidden. Change any figure you have better local data for.
Small squares 20%, round bales 18%, large squares 16%. Source: University of Wisconsin Extension, Team Forage hay drying and storage.
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How to calculate hay moisture
Every forage number worth using — intake, TDN, crude protein, price comparison — is on a dry matter basis, and every load of hay is sold as fed. The conversion is one multiplication in each direction, and skipping it is the single most common way producers overpay for hay.
Dry matter % = 100 − moisture %
lb DM = as-fed lb × dry matter %
as-fed lb = lb DM ÷ dry matter %
$/ton DM = $/ton as fed ÷ dry matter %
Worked example
A 1,100 lb bale at 15% moisture is 85% dry matter, so it holds 935 lb of dry matter and 165 lb of water. To deliver a cow 30 lb of dry matter you must feed 35.3 lb of this hay. At $140 a ton, the dry matter in it costs $165 a ton — meaning a load at 12% moisture would have to be priced at $145 a ton to be the same value.
Common mistakes
- Confusing moisture with dry matter. 18% moisture is 82% dry matter; entering 18% as dry matter turns a bale of hay into a bucket of water.
- Comparing baleage to hay as fed. Half of baleage is water. It must be compared on dry matter, always.
- Trusting one probe reading. Probe several bales at several depths, and core-sample for anything that matters financially.
- Baling just over the safe line. Two extra points of moisture in a big square bale is how stacks heat, mold, and occasionally burn.
As-fed to dry matter conversion at each moisture level
Per 1,000 lb of as-fed hay, plus the as-fed pounds needed to deliver 30 lb of dry matter to a cow, and the equivalent value of hay priced at $140 a ton at 12% moisture.
| Moisture | Dry matter | lb DM per 1,000 lb | lb as fed for 30 lb DM | Equal value vs $140 hay at 12% |
|---|---|---|---|---|
| 8% | 92% | 920 lb | 32.6 lb | $146 |
| 10% | 90% | 900 lb | 33.3 lb | $143 |
| 12% | 88% | 880 lb | 34.1 lb | $140 |
| 15% | 85% | 850 lb | 35.3 lb | $135 |
| 18% | 82% | 820 lb | 36.6 lb | $130 |
| 20% | 80% | 800 lb | 37.5 lb | $127 |
| 25% | 75% | 750 lb | 40.0 lb | $119 |
| 40% (wrapped) | 60% | 600 lb | 50.0 lb | $95 |
| 50% (baleage) | 50% | 500 lb | 60.0 lb | $80 |
| 60% (baleage) | 40% | 400 lb | 75.0 lb | $64 |
Calculators to run next
- Hay Storage Loss CalculatorUse when weighing a shed, tarp or gravel pad against bales sitting on dirt.
- Winter Hay CalculatorStart here when you need to size the stack for the winter before you buy.
- Round Bale Weight CalculatorUse when you are guessing at bale weight and every other hay number depends on it.
- Hay Bale CalculatorUse to convert between tons quoted by a seller and bales you actually load.
- Hay Cost Per Ton CalculatorUse to compare two loads priced per bale, or hay quoted at different moistures.
- Hay Waste CalculatorUse when deciding whether a cone ring or cradle feeder pays for itself.
Guides that use this calculator
- Pricing Hay by the Ton Instead of by the BaleTwo loads at the same price per bale can differ 40 percent on cost per ton of dry matter. Here is the conversion.
Questions ranchers ask
What moisture should hay be baled at?
Small square bales are safe at 18 to 20% moisture, round bales at 15 to 18%, and large squares at 12 to 16% because the denser and larger the package, the less heat it can shed. Baleage is the opposite end — wrapped at 45 to 60% moisture and fermented rather than dried.
How do I convert as-fed hay to a dry matter basis?
Multiply the as-fed weight by the dry matter percentage. A 1,100 lb bale at 85% dry matter contains 935 lb of dry matter. To go the other way, divide: 30 lb of dry matter at 85% requires 35 lb of as-fed hay.
Why does hay moisture matter when buying hay?
Because you pay for the water. A ton of hay at 78% dry matter carries 440 lb of water; the same ton at 88% carries 240 lb. At $140 a ton, that extra 200 lb of water costs you $14 per ton and brings a mold risk with it.
At what moisture will hay heat or catch fire?
Bales above about 20% moisture support microbial activity that generates heat. Internal temperatures over 150 °F cause caramelization and protein damage; above 175 °F the stack is a fire risk and should be monitored with a probe thermometer, and above 190 °F you should call the fire department before moving anything.
How accurate are hay moisture probes?
Handheld probes are useful for relative readings and for deciding whether to keep baling, but they read the surface of a windrow or the outside of a bale and can be several points off. For a purchase decision or a ration, send a core sample to a forage lab for oven dry matter.
How do I take a proper hay sample?
Use a core probe on 15 to 20 bales from the same lot, sampling the round end of round bales and the small end of squares, going in 12 to 18 inches. Combine the cores in a sealed bag and send them in the same day. Grab samples pulled by hand are not worth the postage.
Does a preservative let me bale wetter hay?
Buffered propionic acid products allow baling at roughly 20 to 25% for round bales and up to about 30% for small squares when applied at the label rate, and they suppress mold rather than dry the hay. They add cost per ton and do not rescue hay that is genuinely soaked.
How does moisture change what I feed?
Cattle eat to fill a dry matter requirement. If your hay goes from 88% to 80% dry matter you have to feed roughly 10% more pounds to deliver the same nutrition, which changes both the bale count for the winter and the price you should be willing to pay per ton.
Buy documented pounds, not appearances
A wet bale and a dry bale look identical on a trailer, and one of them is a third water. The same logic runs through the cattle trade — which is why every Agrilot lot carries actual weights, verified seller records and an independent condition report rather than a flattering photograph.