Pig Weight Calculator — Estimate a Hog’s Weight with a Tape
Estimate a pig or hog’s live weight without a scale from heart girth and body length (girth² × length ÷ 400) in kg or lb, plus the likely carcass weight and a weight-by-girth table.
How it works
US: weight (lb) = heart girth² (in) × length (in) ÷ 400 · Metric: weight (kg) = heart girth² (m) × length (m) × 69.3 · Carcass ≈ 74% of live weight.
The tape method from the Old Farmer’s Almanac, widely repeated by pig extension and industry sources, multiplies heart girth squared by body length (base of the ears to the base of the tail) and divides by 400 for pounds; the metric version multiplies metres by 69.3 for kilograms. It works best on finishing pigs between about 30 and 150 kg; very young piglets and fat sows are estimated less reliably. A typical market hog dresses out at around 72–75% of its live weight as a hot carcass.
Worked example
A pig with a 100 cm heart girth and 100 cm body length: 1.00² × 1.00 × 69.3 = 69.3 kg (152.8 lb). Its likely range is 64–74 kg and its hot carcass would weigh about 51.3 kg.
Sources: The Pig Site — Weighing a pig without a scale (girth² × length ÷ 400; metric × 69.3)
Frequently asked questions
How do I measure a pig for the formula?
Heart girth goes around the chest right behind the front legs. Length runs along the middle of the back from the point between the ears to the base of the tail. Measure with the pig standing, head level, using a soft tape.
How accurate is weighing a pig with a tape?
For finishing pigs the formula is usually within about 5–7% of scale weight. Accuracy falls for piglets, heavily pregnant sows and pigs that are very fat or thin.
What is the carcass weight of a pig?
The hot carcass (after bleeding, scalding and evisceration, head on) is typically 72–75% of live weight; this calculator uses 74%. Cut and trimmed retail meat is much less — roughly 50–60% of live weight.
At what weight is a pig ready for slaughter?
Most commercial pigs are marketed at about 110–130 kg (240–290 lb) live weight, although local markets and breeds vary. Use the pig days-to-market calculator to plan when they will get there.
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This calculator is for educational purposes. Double-check important results before acting on them.