Cattle Weight Calculator: Estimate Live Weight from Body Measurements

Weighing cattle accurately requires a weighbridge or crush-mounted load cells — equipment that many smallholders and smaller farms do not have. The Cattle Weight Calculator provides a reliable weight estimate using a simple tape measure and the widely used girth-length formula, giving you a good approximation for dosing, marketing decisions, and growth monitoring.

The calculator uses the metric form of the Schaeffer girth-length formula: weight (kg) = (girth cm² × length cm) ÷ 11,900. This is adapted from the imperial formula commonly used in North America and validated against UK breed weight data. Heart girth is measured around the chest just behind the front legs; body length is measured from the point of the shoulder to the pin bone.

A five-tier weight classification is returned alongside the estimate: Calf (under 200 kg), Store (200–350 kg), Growing (350–500 kg), Finishing (500–650 kg), and Heavy/Mature (over 650 kg). Out-of-range measurements are flagged with a warning to prompt a re-measure.

The Schaeffer formula has been in widespread use since the 1970s and is referenced in veterinary dosing guides as an acceptable method of weight estimation when scales are unavailable. Accuracy is typically within 5–10% of true weight for well-conditioned cattle of standard breeds; accuracy may be lower for very lean or very fat animals and for breeds with unusual conformation such as double-muscled Belgian Blues.

Measure the heart girth with a soft tape measure, drawing the tape snugly around the chest just behind the front legs, and record the measurement in centimetres. Measure body length from the point of the shoulder to the pin bone along the topline. Enter both measurements into the calculator. The estimated weight and classification will appear immediately.

For dosing purposes, it is advisable to round up to the nearest 50 kg and confirm with your vet. Never underdose based on an estimated weight alone.