Hay bale calculator
Enter how many animals you feed, their average weight and daily intake, the length of the feeding season and the weight of your bales. The calculator gives the bales and the total hay to put up. Intake, dry matter and waste are rules of thumb you can change to fit your animals and your hay.
Runs in your browser: nothing you enter is sent anywhere.
How to use it
- Enter the number of animals and their average weight.
- Set the daily dry matter intake (a common rule of thumb is 2–2.5% of body weight) and the feeding period.
- Enter the dry matter share of your hay, the waste allowance and the bale weight, then read the bales needed.
How it works
- dry matter per animal a day = weight × intake %;
- hay as fed = dry matter ÷ dry matter share of the hay;
- hay for the season = hay per animal × animals × days × (1 + waste %);
- bales = hay for the season ÷ bale weight, rounded up.
Example
10 cows of 1,200 lb, 2.5% intake, 150 days, hay at 88% dry matter, 15% waste, 1,000 lb round bales:
- 1,200 × 0.025 = 30 lb of dry matter; ÷ 0.88 = 34.1 lb of hay per cow a day;
- the herd eats 340.9 lb a day; × 150 days × 1.15 = 58,807 lb, or 29.4 short tons;
- 58,807 ÷ 1,000 = 58.8, so put up 59 bales.
Tips and common mistakes
- Plan for a longer winter than average; a late spring can add weeks of feeding.
- Pregnant and nursing animals eat more than dry ones, and young stock eat more per pound of body weight.
- Get the hay tested if you can: its quality changes how much animals eat as well as how well they do.
Frequently asked questions
How many round bales does a cow eat in winter?
With the defaults, a 1,200 lb cow eating 2.5% of its weight in dry matter needs about 34 lb of hay a day. Over 150 days with 15% waste that is about 5,900 lb, or roughly six 1,000 lb bales per cow. Your own numbers will differ.
How much does a bale of hay weigh?
It varies a lot with size, density and moisture. Small square bales are often 40–70 lb, round bales several hundred pounds to over 1,000 lb. Weigh a few of your own bales if you can.
Why is dry matter in the calculation?
Intake guidelines are given in dry matter, but hay still holds some water. Dividing by the dry matter share (often around 85–90% for dry baled hay) converts dry matter to hay as fed.
How much waste should I allow?
It depends on how you feed. Hay fed on the ground or in open rings loses more than hay in a covered feeder. The 15% default is only a starting point; set it from your own experience.