Winter Hay Calculator
Work out the tons and bales your herd needs for the whole feeding period, waste and reserve included.
Your numbers
Hay to buy or bale for 50 head over 120 days
145 tons of hay
- Bales needed
- 264 bales
- Bales per head
- 5.3 bales
- Fed per head per day
- 42 lb as fed
- Waste alone accounts for about 18.9 tons — roughly 34 bales that never reach a cow's rumen.
- Weigh three or four bales before you trust this number. A 200 lb error in assumed bale weight moves a 50-cow winter by 10 or more bales.
Show the math
- Dry matter intake1,300 lb × 2.3% (last trimester) × 1.05 cold = 31.4 lb DM/day
- Converted to as-fed hay31.4 ÷ 88% dry matter = 35.7 lb/day
- Grossed up for waste35.7 ÷ (1 − 15%) = 42.0 lb offered/day
- Whole herd, whole period42.0 × 50 head × 120 days × 1.15 reserve = 289,606 lb
- In tons and bales289,606 ÷ 2,000 = 144.8 tons; ÷ 1,100 lb/bale = 263 bales
Assumptions this calculator used
Nothing here is hidden. Change any figure you have better local data for.
Extra intake for days below the cow's lower critical temperature. Source: NRC Nutrient Requirements of Beef Cattle — cold stress adjustment.
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How to calculate winter hay
Hay budgeting starts with the cow, not the bale. Take her dry matter intake as a percentage of body weight, convert that to as-fed pounds at the moisture of your hay, gross it up for what the feeder throws on the ground, then multiply out by head and days and add a reserve.
lb DM/day = cow weight × intake %
lb as fed/day = lb DM ÷ hay dry matter %
lb offered/day = lb as fed ÷ (1 − waste %)
Total = lb offered × head × days × (1 + reserve %)
Worked example
A 1,300 lb cow in her last trimester eats 2.3% of body weight, or 30 lb of dry matter a day. At 88% dry matter that is 34 lb of hay. Feeding in an open ring at 15% waste means putting out 40 lb a day. Fifty cows for 120 days is 240,000 lb, and a 15% reserve takes it to about 138 tons — roughly 251 bales at 1,100 lb.
Common mistakes
- Trusting the bale spec sheet. A 5x6 bale of loose grass hay can weigh 850 lb and a tight 5x5 alfalfa bale 1,200 lb. Weigh, don't assume.
- Leaving waste out. The cow eats what she eats; the difference between a cone ring and hay rolled out on frozen ground is 20 percentage points of your stack.
- Budgeting an average winter. Two ice storms and a late spring is the winter that empties the barn.
- One number for the whole herd. Bulls, bred heifers and lactating cows have genuinely different intakes — run each group.
Hay required per head per day by cow weight and production stage
Pounds of as-fed hay at 88% dry matter, before feeding waste. Add your waste percentage on top of these figures to get what you actually have to put out.
| Cow weight | Dry, mid-gestation | Last trimester | Lactating | Bred heifer |
|---|---|---|---|---|
| 1,000 lb | 23 lb | 26 lb | 30 lb | 28 lb |
| 1,100 lb | 25 lb | 29 lb | 33 lb | 31 lb |
| 1,200 lb | 27 lb | 31 lb | 35 lb | 34 lb |
| 1,300 lb | 30 lb | 34 lb | 38 lb | 37 lb |
| 1,400 lb | 32 lb | 37 lb | 41 lb | 40 lb |
| 1,500 lb | 34 lb | 39 lb | 44 lb | 43 lb |
| 1,600 lb | 36 lb | 42 lb | 47 lb | 45 lb |
Calculators to run next
- 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.
- Hay Moisture CalculatorUse before comparing prices — wet hay carries tons of water priced as forage.
- Hay Storage Loss CalculatorUse when weighing a shed, tarp or gravel pad against bales sitting on dirt.
Guides that use this calculator
- Body Condition Scoring Beef Cows and Why BCS 5 PaysWhat each score looks like by hand and eye, and why a cow calving at BCS 4 costs you a breeding season.
- Budgeting a Winter Hay Supply Before the First FrostBales per cow per day, waste by feeding method, and how much of the stack a February cold snap really takes.
Questions ranchers ask
How many bales of hay does one cow need for winter?
A 1,300 lb spring-calving cow eating 2.4% of her body weight in dry matter needs about 31 lb DM a day, which is roughly 35 lb of 88% dry matter hay. Over a 120-day feeding period with 15% waste that is about 4,800 lb, or five to six 1,000 lb round bales per cow. Bale weight drives that number more than anything else, so weigh a bale before you plan on it.
How long is a typical hay feeding period?
It runs from 60 days on the Gulf Coast and in the Southwest to 180 days or more in the Northern Plains. Most of the Midwest and Upper South budgets 120 to 150 days. Add two to three weeks of reserve on top for an ice storm or a late spring — running out in March is what forces people to buy hay at the worst price of the year.
Does a cow eat more hay in late gestation?
Yes. Dry matter intake climbs from about 2.0% of body weight for a dry mid-gestation cow to roughly 2.3-2.4% in the last trimester and 2.6-2.7% once she is lactating. Because that increase lands in the coldest months, hay demand and cold stress peak together.
How much extra hay does cold weather add?
Below a cow's lower critical temperature — around 32 °F with a dry winter coat, closer to 59 °F if she is wet — maintenance energy rises roughly 1% per degree of cold. A week of 0 °F weather can lift intake needs 20-30%. Budget an allowance for it rather than assuming an average winter.
Should I plan hay on an as-fed or dry matter basis?
Do the animal math on dry matter, then convert to as-fed at the moisture of the hay you actually own. Hay at 88% dry matter and hay at 78% dry matter feed very differently per bale even at the same bale weight, and the wetter bale is also the one more likely to heat and mold.
How much hay should I keep as a reserve?
Most extension budgets suggest 15 to 25% above the calculated need — call it two to four extra weeks. That covers a storm, a late green-up, and the bales at the bottom of an outside stack that end up too rotten to feed.
Can I stretch hay with supplement or stockpiled forage?
Yes, and it is usually cheaper than buying hay in February. Stockpiled fescue grazed through December and January can remove 45 to 60 days from the hay budget. Limit-feeding a high-energy byproduct like corn gluten feed or soyhulls with restricted hay access also works, but it needs bunk space for every cow at once.
Do bulls and replacement heifers change the total?
They do. Run them as separate groups: a mature bull at 1,900 lb eats about 40 lb of hay a day, and bred heifers need higher-quality hay because they are still growing while carrying a calf. Feeding one average ration to the whole herd overfeeds the cows and underfeeds the heifers.
Winter feed cost is the number that decides which cows stay
If a cow costs six bales to winter, she has to wean a calf worth more than that plus everything else she consumes. Agrilot lists registered Angus females with documented calving intervals and weaning weights, so you can see what a replacement is likely to pay back before you bid.