Cattle Weight Calculator — Heart Girth Tape & Schaeffer Formula
Estimate a cow, steer or heifer’s live weight without a scale from heart girth and body length with the Schaeffer formula — in kg or lb, with a likely range and a weight-by-girth table.
How it works
US: weight (lb) = heart girth² (in) × body length (in) ÷ 300 · Metric: weight (kg) = heart girth² (cm) × body length (cm) ÷ 10,838 (the same formula converted to centimetres and kilograms).
The Schaeffer formula treats the body as a cylinder: heart girth squared times body length is proportional to volume, and the divisor turns that volume into weight. Field studies comparing it with scale weights find it usually lands within about 5–10% for adult beef and dairy cattle — accurate enough for dosing dewormers, planning feed and judging growth, though very fat, thin, pregnant or young animals stray further. Measure twice and average, with the animal standing square on level ground.
Worked example
A steer with a heart girth of 180 cm and a body length of 150 cm: 180² × 150 = 4,860,000; ÷ 10,838 = 448.4 kg (about 988.6 lb). Allowing ±7%, the true weight is most likely between 417 and 480 kg.
Sources: Ozkaya & Bozkurt — Use of Schaeffer’s formula for the prediction of body weight of slaughtering cattle · Wangchuk et al. (2018) — Comparison and reliability of techniques to estimate live cattle body weight, J. Applied Animal Research
Frequently asked questions
Where exactly do I measure heart girth?
Pass the tape around the chest immediately behind the front legs and the shoulder blades, snug but not tight, with the animal standing square and its head up. Read it when the animal has breathed out.
How do I measure body length?
From the point of the shoulder (the front of the shoulder joint) along the side to the pin bone (the bony point beside the tail head). Use a straight line, not one that follows the curve of the belly.
How accurate is a weight tape?
Studies of the Schaeffer formula report typical errors of 5–10% against a scale. It is less reliable for calves, very fat or very thin cattle, and late-pregnant cows, so use a scale for sales or precise drug dosing when one is available.
Can I use only heart girth?
Commercial weight tapes convert girth alone using breed-average body shape, which is quicker but less accurate. Adding body length, as this formula does, accounts for long and short animals of the same girth.
Does this work for horses or pigs?
No — the divisor is fitted to cattle. Horses and pigs have their own girth-and-length formulas; use the horse or pig weight calculators instead.
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This calculator is for educational purposes. Double-check important results before acting on them.