Sheep behind a post-and-wire fence on a farm near Hunterville under a blue sky
Handy tools

Stock units (SU) calculator

One stock unit is roughly what a 55 kg ewe rearing a single lamb eats in a year. Enter your mob numbers to see total SU, SU per hectare and how much feed the farm needs.

Hunterville, Rangitīkei · Photo: AnnWoolliams, CC BY-SA 4.0

Type the number of head in each class. The SU per head boxes start at a typical New Zealand guide value - change them to suit your stock.

Sheep hipi1,921 SU
Breeding ewes45–65 kg, 90–130% lambing · guide 0.85–1.25 SU
Hoggets30–50 kg, slow to fast growth · guide 0.7–1.2 SU
Ramsabout 75 kg
Beef cattle kau1,120 SU
Beef breeding cows400–500 kg, rearing a calf · guide 4.4–6.3 SU
Weaners (R1)135–270 kg
Heifers, steers, bulls (R2)200–500 kg, slow to fast growth · guide 3.7–4.7 SU
Mature bulls, heavy steersabout 600 kg
Dairy cattle kau miraka0 SU
Dairy cows (milking)350–450 kg, 140–200 kg milkfat · guide 6.1–8 SU
Dairy yearlingsJersey to Friesian, 180–430 kg · guide 3.5–4.5 SU
Dairy calvesJersey to Friesian, 25–225 kg · guide 2–2.5 SU
Deer tia0 SU
Red deer hindsmature, about 100 kg · guide 1.8–1.9 SU
Red deer stagsmature, about 185 kg · guide 2.1–2.2 SU
Young deer (6–15 months)red deer, 50–80 kg
Goats nanekoti0 SU
Dairy goat does45–60 kg, milking · guide 1.5–2 SU
Angora or cashmere goats25–50 kg · guide 0.5–1 SU

Your farm - optional, for per-hectare figures and the feed check

Grazed area only - leave out bush, tracks, yards and waterways.

550 kg is the usual figure; some advisers use 520.

From your own records or your farm adviser. Leave empty to skip the feed check.

Share of the grass grown that stock actually eat.

Your farm in stock units

3,041stock units
6.8SU per hectare
1,673t DM a year needed
  • Sheep 63%
  • Beef cattle 37%
Head of stock
2,194
Sheep : cattle (by SU)
63 : 37
Feed demand per hectare
3,717 kg DM
Link to this tally

How we work it out

  • Stock units: head × SU per head for each class, added up. One SU is about the yearly feed of a 55 kg ewe rearing a single lamb.
  • Stocking rate: total SU ÷ effective hectares. Sheep : cattle compares sheep SU with beef and dairy SU.
  • Feed check: demand = SU × kg DM per SU. Pasture eaten = hectares × pasture grown × utilisation. The gap is the yearly feed balance.

A guide only. SU per head figures are typical New Zealand guide values and vary with liveweight, lambing or calving percentage, milk production and growth rate - your farm adviser, vet or the benchmarking data for your farm class will give a closer number. Feed demand is spread unevenly through the year, so a farm can balance over a year and still be short in winter or a dry summer. Nothing you type is sent anywhere; Save my farm keeps one tally in this browser only, so you can come back to it. Words like DM, effective area and SU are in the farm words glossary; regional farm types are in the farming regions guide. Planning for summer? The stock water calculator adds up the litres your stock drink on a hot day, and the lambing percentage calculator tracks your ewes from scanning to weaning.

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