Cattle per Acre Calculator, Formula, Calculation & Example

Cattle per Acre Calculator

This calculator will tell you how many cattle per acre can graze . Continue reading to learn more about Animal Unit Month and how different pasture conditions affect how many cows per acre may be suitable.

You might also like to ask this question in a different way How many spaces does a cow require? This is the place to find the answer!

The animal unit — How many acres does a cow require?

The Animal Unit (AU), a universal measurement that allows you to estimate the number of cattle you can graze on an acre, is called the Universal Measure. A 1000-lb cow and a calf up to six months old is one AU.

A cow typically consumes 75-80% of its weight each month in forage. A calf does not need grass to graze, but it still consumes cow milk. This results in a higher forage intake by the mother.

Another standard measure is AUM, which is the monthly forage requirement for 1_. Natural Resources Conservation Service. NRCS. 1 AUM equals 915 lb.

We need to calculate the yield of pasture forage in order to determine how many acres a cow requires. These numbers can range from 0.25 to 7.75 AUM/ac. These numbers can be affected by many factors:

  • Pasture condition
  • Precipitation zone;
  • Type of forage;
  • Grazing strategy (e.g., rotational grazing).

We focus on the first two factors in our cattle per acre calculator. To see an estimate of the forage production, please refer to the Alberta Forage Manual table.

see the estimated values of forage production:

Annual precipitation zones Pasture condition class (yield in AUM/ac)
Excellent Good Fair Poor
250-350 mm 0.75 0.50 0.40 0.25
350-450 mm 1.25 0.80 0.60 0.40
450-550 mm 2.00 1.40 1.10 0.70
550-650 mm 3.30 2.20 1.60 1.10
Irrigation 7.50 5.00 3.75 2.50

What amount of land does a cow require?

A typical 1000-lb cow and a calf (1Animal Unit) need 0.27 acres (0.11ha) of grass in good condition and applied irrigation. 8 acres (3.2ha) is needed for pasture in poor conditions and low precipitation. A 1300lb cow and a calf (1 AU) require 0.34 to 10.3 ac, 0.14 or 4.2 ha land.

Do you want to know how much it will cost for cattle fencing? The livestock fence cost calculation will help you budget for your cattle fencing.

Calculator for how many cattle you can use per acre

Let’s look at the steps together to see how our cattle per acre calculator works.

  1. Select the type of cattle that you would like to graze. You can choose the Custom option if you know the mean animal unit for the herd and enter your own value.
  2. Enter the area total of the pasture. If you only know the dimensions for the field, check our area calculator.
  3. You can choose to use the annual rainfall or pasture conditions if you don’t have an idea of the forage yield. You can enter the value if you know the number.
  4. That’s all! In the result section, you can view the cumulative forage production of pastures, the total cattle and the maximum number of cows per acre that can be grazed on the field.
  5. You can adjust other parameters, such as the utilization rate, to suit your needs. If you have a good idea of the forage yield and would like to change the lb - AUM conversion rate — default is 915lb/AUM.

To keep your cattle business running smoothly, you might also be interested to check the cow mortality rate calculator and cow gestation . For a refresher in math, please visit our How to Do Ratios article.

What number of acres are needed for a cow? A sample computation

Let’s look at an example to show you how to calculate how much land a cow requires.

Let’s say we need to determine the number of cows that will fit in an 800c pasture in a good condition. For the calves and cows, we want to maintain a herd that has an average weight of 1300lb . The average annual precipitation is 550 up to 625. 50% is the utilization rate.

  1. Good pasture conditions and the precipitation zone ensure an average forage yield of 2.0 AUM/ac, or 2000 Lb/ac.
  2. The total field production is 2000 Lb/ac * 50% = 1,000 Lb/ac.
  3. 800 acres pasture can be used to collect 1000 pounds/ac * 800 acres = 800,000 lb forage. You can also write it 800, / = 874.
  4. 1.3 is an animal equivalent to our cows, so the total cattle count is 874/1.3 = 673.
  5. We can also estimate the number of cattle per acre (assuming a pair calf and cow as one unit). 673/800 = 0.84 cattle/ac.
  6. You can also ask this question in reverse . How many acres do you require for each cow ? Find the multiplicative inverted of the previous number 1/ 0.84 = 1.19 ac for each cow.

Tame pasture condition classes explanations

You can find out more about the different types of pasture conditions by checking out the Alberta Forage Manual.

Category Excellent Good Fair Poor
Potential yield of the area 75-100% 60-75% 50-60% 33-50%
Production from desirable, adapted grass and legumes 95% 90% 60% Less than 50%
Production from weeds or undesirable plants Less than 5% Less than 10% 20% or more 50% or more
Fertility program Average to above average Average Below average or non-existent No fertility program


Remember that the rough estimates of the cattle per acre calculator and the table’s values are only estimates . The actual yield of a pasture will vary depending on the type of grass and legume used. Forage production can change throughout the year.

What is the maximum number of cows I can have on an acre with rotational grazing

should be capable of keeping between 0.55 and 1.11 cows/acre on an average pasture. Rotational grazing can increase the cows per acre by up to 30%, compared to traditional grazing. Rotational grazing requires at most two paddocks, and is usually more costly.


Leave a Comment