How it works
The tape method estimates weight from two measurements: heart girth (around the chest just behind the front legs) and body length. The formula is girth × girth × length, divided by a number that suits the species. For animals in normal condition it usually lands within 5–10% of scale weight.
How to use it
Have the animal stand square on level ground with its head up. Take the girth right after it breathes out. Measure twice and use the average.
Reference chart
| Animal | Formula (inches → lb) | Body length measured |
|---|---|---|
| Cattle | girth² × length ÷ 300 | shoulder point to pin bone |
| Goat / sheep | girth² × length ÷ 300 | shoulder point to pin bone |
| Pig | girth² × length ÷ 400 | between the ears to tail base |
| Horse | girth² × length ÷ 330 | shoulder point to point of buttock |
Frequently asked questions
How accurate is a weight tape?
Usually within 5–10% for adult animals in normal body condition. Very fat, thin, pregnant, young or unusually built animals can be further off.
Where do you measure heart girth?
Around the body just behind the front legs and elbows, over the top of the withers or shoulders. Keep the tape snug but not tight.
Can I use this for medicine doses?
Use a scale whenever a dose depends on weight. If you have to use a tape estimate, confirm the dose with your vet.
How do I weigh a goat without a scale?
Measure heart girth and length in inches and use girth × girth × length ÷ 300. Choose 'Goat' above and the calculator does it for you.
Figures are typical values from university extension and breed-association guidance. Estimates only. Individual animals vary — confirm pregnancy and health questions with your veterinarian. Last reviewed 2026-09-18.