Livestock Stocking Rate Calculator
Work out how many animals your pasture can carry for the season from acres, forage per acre, utilization, and animal size, or how long your herd's grass will last.
Free · no account · works on mobile · embeddable
Best for graziers and small farms sizing a herd or flock to their pasture. Updated .
Your pasture
The animals
What the pasture can carry
Usable forage = acres × lb per acre × utilization %. One animal unit eats 26 lb of forage a day (a 1,000 lb cow with calf). Head supported = usable forage ÷ (days × lb per head per day). Forage growth is the weak link: this is a season-planning estimate, not a substitute for walking the pasture and adjusting.
About the livestock stocking rate calculator
"How many cows per acre" has no single answer, because it depends on how much grass the acre grows and how much of it you let the animals eat. This calculator makes the arithmetic honest. Enter grazeable acres, the forage each acre grows over the season, the share you will let the animals harvest, and the size and type of animal, and it returns animal units, the head your pasture can carry for the season, acres per head, and how many grazing days your current herd would get.
The forage figure is the input that matters most and the one nobody can look up for you, so treat the default as a placeholder and replace it with a clipping, your NRCS or extension office's estimate for your soils and rainfall, or last year's hay-equivalent yield.
Animal units and the 26 lb day
Extension uses the animal unit (AU) to compare animals of different sizes: one AU is a 1,000 lb cow, with or without a calf, allotted 26 lb of dry forage per day (20 lb for the cow, 6 for the calf). An animal unit month (AUM) is 26 lb × 30.4 days, about 790 lb. The calculator converts your animal to AUs from its daily forage demand: weight × demand percent ÷ 26. A 1,200 lb cow with calf at 2.6% needs 31.2 lb a day and counts as 1.2 AU; a 150 lb doe at 3% is 4.5 lb a day and 0.17 AU.
Forage, utilization, and the two questions
Usable forage is acres × lb per acre × utilization. Utilization is the share of the grown forage the animals actually eat; the rest is left standing or lost to regrowth, trampling, insects, and wildlife. Take half, leave half describes what is removed, not what is eaten: 50% is the removal guideline; on rangeland Oklahoma State counts only 25% as actually eaten, which is the figure to enter here. On rotationally grazed improved pasture 50% consumed is a common planning figure, and it is the calculator's default because the default forage figure describes improved pasture.
With usable forage in hand the calculator answers two questions. Head supported for the season is usable forage ÷ (grazing days × lb per head per day), rounded down. Grazing days for your herd is usable forage ÷ (head × lb per head per day), which tells you whether the herd you already have runs out of grass before the season ends.
What it does not know
Forage growth is seasonal, so a 180-day figure hides a spring flush and a summer slump. Rotational grazing raises utilization safely; continuous grazing lowers it. Drought can halve production in a single year. Use the result to set a starting stocking rate, then walk the pasture, measure residual height, and adjust. It is a planning estimate, not a grazing plan or an NRCS determination.
Worked example: 20 acres of improved pasture
Twenty grazeable acres growing 3,000 lb of forage per acre over the season at 50% utilization give 30,000 lb of usable forage, which is 1,154 animal unit days or 37.9 AUMs. A 1,200 lb cow with calf at 2.6% of body weight needs 31.2 lb a day and counts as 1.2 animal units. Over a 180-day season the pasture supports 6.4 animal units, which is 5.3 pairs, so 5 cow-calf pairs, at 3.7 acres per pair. A herd of 8 pairs (9.6 AU) would eat 250 lb a day and run out after about 120 grazing days, roughly 60 days short of the season.
Sources
- North Dakota State University Extension, Animal unit equivalent for beef cattle based on metabolic weight. A 1,000 lb cow with or without a calf is 1.00 animal unit with a daily dry matter allocation of 26 lb of forage; an AUM is that allowance for one month. Accessed Sep 4, 2026.
- Oklahoma State University Extension, Stocking rate: the key to successful livestock production (PSS-2871). Defines the animal unit day as a 1,000 lb cow with calf eating 26 lb of dry forage and uses 25% harvest efficiency on native rangeland. Accessed Sep 4, 2026.
This calculator gives planning estimates from the numbers you enter. It is not accounting, tax, veterinary, or legal advice. Replace the defaults with your own farm records whenever you have them.
Frequently asked questions
How many cows can I run per acre?
It depends on forage growth. At 3,000 lb per acre and 50% utilization a 1,200 lb pair needs about 3.7 acres for a 180-day season; at 6,000 lb per acre on well-managed humid pasture it is under 2 acres, and on arid rangeland it can be 20 or more. Enter your own forage figure.
What is an animal unit?
One 1,000 lb cow, dry or with a calf up to about six months, eating 26 lb of dry forage a day. Larger or smaller animals are counted as fractions or multiples: a 1,200 lb pair is about 1.2 AU, a 150 lb goat about 0.17 AU, so roughly six does equal one animal unit.
How many goats or sheep per acre?
Use the same forage math with a 3% of body weight demand. On pasture growing 3,000 lb per acre at 50% utilization, 150 lb does need about 0.5 acre each for 180 days, so roughly 2 does per acre; 175 lb ewes need slightly more. Browse-heavy land and parasite management change the answer.
What utilization rate should I use?
Enter the share actually eaten. On rotationally grazed improved pasture 50% consumed is a common planning figure. On native rangeland Oklahoma State counts only 25% as eaten even though take half, leave half removes 50%, because trampling, insects, and weathering take the rest. Lower utilization means fewer head but healthier pasture next year.
How do I find out how much forage my pasture grows?
Ask your county extension or NRCS office for production estimates for your soil map units, clip and weigh a few square-foot samples through the season, or use last year's hay yield from similar ground as a proxy. A grazing stick gives a quick field estimate in pounds per acre-inch.
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