Livestock weight from heart girth calculator
About how much does my animal weigh, from a tape measure?
Showing for United States
Estimated live weight
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This is an estimate from two tape measurements, not a weighing. The extension sources give no error figure; they call it fairly accurate, and not highly accurate for pregnant animals or animals of unusual build. A scale is the only exact way.
Do not use this weight to dose medicine; weigh the animal or ask your vet.
Stand the animal square on level ground. Measure the heart girth just behind the front legs and shoulders, with the tape snug and flat. Measure the body length from the point of the shoulder to the pin bone; for a pig, from between the ears along the back to the base of the tail.
Measure in inches if you weigh in pounds, or in centimeters if you weigh in kilograms.
Enter your numbers to see the result.
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1. Copy this address
2. Add it to your AI app
Claude (claude.ai and the Claude desktop app)
- Open Customize, then Connectors.
- Press + Add, then Add custom connector.
- Name it TallyTill calculators, paste the address and press Continue.
- Under Authentication choose No sign in, then press Add.
- In a new chat, press + at the bottom left, choose Connectors and switch TallyTill calculators on.
On Claude's free plan you can add one custom connector.
ChatGPT
- In Settings, turn on Developer mode. OpenAI moves this switch from time to time; it is usually with the settings for apps and connectors.
- Add a new connector (ChatGPT may call it an app), paste the address and choose No authentication.
- In a new chat, choose TallyTill from the tools menu, or type @ and pick it.
Not every ChatGPT plan lets you add your own connector. If you cannot find the option, your plan may not include it.
Using another AI app? Look in its settings for MCP, add the address as a remote server, and choose no sign-in.
3. Ask your question
Say "use TallyTill", so the AI uses the calculator instead of doing the sum itself. For example:
"Use TallyTill: About how much does my animal weigh, from a tape measure?"
What you will see
- The calculator opens in the chat with the numbers you gave already filled in. Change any number and the answer updates.
- If a number is missing, the box is highlighted, or the AI asks you for it in plain words.
- The answer links back to this page, so you can check the working.
- The first time, your AI app asks if it may use TallyTill. Choose Allow.
The calculators take numbers only. They never ask for your name, your email or a password.
How this is worked out
The estimate is the heart girth times the heart girth times the body length, in inches, divided by 300 for cattle, sheep and goats, or by 400 for pigs, which gives pounds. For a pig whose figure comes out under 150 pounds, 7 pounds are added. If you weigh in kilograms, measure in centimeters: each length is converted to inches exactly (2.54 cm to the inch) and the pounds to kilograms exactly (0.45359237 kg to the pound). The answer is rounded to a whole pound or kilogram. This is the method published by Oregon State University Extension and University of Arizona Cooperative Extension.
A worked example
Example numbers only; use your own. Oregon State University Extension's example beef cow has a heart girth of 70 inches and a body length of 78 inches: 70 × 70 × 78 ÷ 300 = 1,274 lb. Its example pig, 45 inches around and 54 inches long, is 45 × 45 × 54 ÷ 400 = 273 lb. A smaller pig, 35 inches around and 36 inches long, works out at 110.25 lb, under 150, so 7 lb are added: 117 lb.
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