How many acres do you need per cow?

Short answer

About 2–2.6 acres per cow on good eastern pasture year-round — 30 or more on dry range. Your grass decides, not a rule of thumb

A 1,000-lb cow eats about 30 lb of forage dry matter a day, 10,950 lb a year. On average eastern pasture growing 3 tons an acre and grazed rotationally, where the cow gets about 70% of it, that is about 2.6 acres per cow for the whole year; at 4 tons, about 2 (Shelton, NRCS, in Ohio State's beef letter). Graze one pasture continuously and the cow only gets 30–50%, so you need nearly twice the land. On dry western range the same cow can need 30 acres for half a year. Most small farms graze part of the year and feed hay for the rest — the calculator splits it for you.

The arithmetic

Forage per day = body weight × 3% (dry matter). A 1,200-lb cow: 36 lb. Shelton calls 3% the safe average; NRCS's animal-unit figure is 26 lb for a 1,000-lb cow with calf.
Forage for the season = per day × grazing days. 36 lb × 200 days = 7,200 lb.
Usable forage per acre = pasture yield × the share the cow actually gets. 6,000 lb (3 tons) × 70% rotational = 4,200 lb; × 40% continuous = 2,400 lb.
Acres = season forage ÷ usable per acre. 7,200 ÷ 4,200 = 1.7 acres per cow rotational; 3.0 continuous. The other 165 days are hay: about 6,800 lb a cow from a feeder.

Why does one source say 2 acres per cow and another 30?

They are all right — about their own grass.

Victor Shelton (NRCS), Ohio State beef letter: 1,000-lb cow, year-round: about 2.6 acres at 3 tons/acre, about 2 acres at 4 tons, both at 70% grazing efficiency
University of Wyoming B-1320: A rangeland example of 0.2 AUM per acre: 50 cows for 6 months on 1,500 acres — 30 acres a cow for half a year
University of Maine: Good pasture grows about 275 lb per acre-inch; grazed from 8 inches to 3, that is about 45 cow-days per acre per pass
NRCS animal-unit table (via Oregon State, Arizona): Cow with calf, 1,000 lb = 1.0 AU at 26 lb/day; dry cow 0.92; bull 1.35; a 1,200-lb cow with calf is 1.2

Rainfall and soil set the yield, and the yield runs from a few hundred pounds an acre on dry range to 8,000 on good eastern pasture — more than a 10× spread before management even enters. Then grazing efficiency doubles or halves it again. A single "acres per cow" rule is wrong for almost everyone who uses it.

Find your yield (NRCS Web Soil Survey, or your county office), decide whether you graze rotationally, and do the division. If you can't find a yield, start from 3 tons and watch the grass.

What changes your number

Pasture yield. The biggest number on the page. Oregon State points to NRCS Web Soil Survey for the potential yield of your soil.
Rotational or continuous. Well-managed rotation gets about 70% of the grass into the cow; one pasture all season gets 30–50% (Shelton). Same land, nearly twice the cows.
Take half, leave half. The range rule of thumb: graze about half the forage and leave the rest to regrow (Wyoming).
Cow size. A 1,400-lb cow is 1.4 animal units, not 1 (Wyoming, NRCS). Modern cows are bigger than the 1,000-lb cow the old rules were written for.
Calves and bulls. A cow with calf is 1.0 AU, a dry cow 0.92, a yearling 0.6, a mature bull 1.35 (NRCS).
Grazing days. Every day not grazed is a day of hay. A 200-day season on 1.7 acres a cow still needs about 6,800 lb of hay for the other 165.

A number we won't give you

A per-state acres-per-cow table. Yields vary within a county as much as between states; we'd be printing someone else's grass. The calculator takes yours.

Acres per 1,200-lb cow — 200 grazing days

Pasture	Acres per cow	Cows per acre	Hay for the other 165 days
Dry rangeland, 1,500 lb/acre, take half–leave half	9.60 acres	0.1	6,831 lb
Average eastern pasture, 3 tons, continuous (40%)	3.00 acres	0.3	6,831 lb
Average eastern pasture, 3 tons, rotational (70%)	1.71 acres	0.6	6,831 lb
Good pasture, 4 tons, rotational (70%)	1.29 acres	0.8	6,831 lb

Intake 3% of body weight (Shelton). Yields and efficiencies from Wyoming (rangeland example) and Shelton (3 and 4 tons, 70% rotational, 30–50% continuous). Hay includes 15% feeder waste.

Animal units — what one cow's grass feeds instead

Animal	Animal units	Per cow-with-calf
Cow, 1,000 lb, with calf	1.00	1
Cow, 1,000 lb, dry	0.92	1.1
Bull, mature	1.35	0.7
Yearling	0.60	1.7
Horse, mature	1.25	0.8
Ewe, mature	0.20	5
Goat, mature	0.15	6–7

NRCS National Range and Pasture Handbook, as tabled by Oregon State EM 9552 and the University of Arizona. Scale cows by weight: 1,200 lb with calf = 1.2.

Run your own numbers

Five 1,200-lb cows on a 200-day grazing season — put in your head count, your grass and how you graze.

Your animals and your grass

SpeciesHeadAvg weight (lb)

Grazing days a yearThe rest of the year is hay.Pasture yield (tons dry matter / acre / yr)3 is Shelton’s average for good eastern pasture; dry range can be a few hundred pounds. NRCS Web Soil Survey has yours.How you graze

Intake is 3% of body weight in dry matter a day — the “safe average” in Shelton and Maine’s worksheets.

Pasture you need

8.6 acres

Acres per head: 1.71
Cattle per acre: 0.6
Forage per head per day: 36.0 lb
Hay for the rest of the year: 34,155 lb

Graze cattle on fewer acres than this and the difference comes out of the hay pile — or out of next year’s grass.

Pasture versus the hay pile

Every acre you don't have is hay you buy. At the cattle hay page's 30 lb a day, a 1,200-lb cow off pasture for 165 days needs about 6,800 lb — 3.4 tons — with feeder waste, roughly $410–510 at Cornell's round-bale prices of $120–150 a ton. Better grazing management that moves a cow from 40% to 70% efficiency is the cheapest pasture you'll ever add.

Then stop planning from averages

The calculator is the plan. In Homestead Paradise you record which paddock the animals are on and the app counts rest days for every paddock, the hay you buy for the off-season lands on the herd's feed cost per head, and the herd's weights and records sit beside it. 14-day free trial, no card.

Start your 14-day trial — no card

Keep planning

How many goats per acre?How many sheep per acre?How many laying hens do I need?How much coop space does a chicken need?How many meat chickens should I raise?How much hay do goats need for winter?

Sources

Every figure on this page comes from a land-grant university extension service, a government agriculture or energy agency, or a breed registry — never from another blog.