Pasture Forage Mass Calculator — Clipping Frame Method & Grazing Days
Estimate pasture forage dry matter per hectare or acre from clipped quadrat samples, the usable forage in a paddock and how many days it will feed your herd.
How it works
Fresh forage (kg/ha) = grams per frame ÷ 1,000 ÷ frame area (m²) × 10,000 · Dry matter (kg DM/ha) = fresh × DM% · Usable forage = DM/ha × utilisation × area · Grazing days = usable forage ÷ (animals × body weight × intake %)
Clipping a known area is the reference method for measuring pasture: throw a frame at random in at least 10 representative spots, cut the forage inside at grazing height, weigh it and average. Scaling grams per frame to a hectare gives green forage; multiplying by dry-matter content converts it into the dry matter animals actually live on. Allowing only about half to be eaten and dividing by the herd’s daily intake (roughly 2.5% of body weight for cattle) turns the measurement into a grazing plan.
Worked example
With a 0.25 m² frame averaging 500 g of fresh grass: 0.5 kg ÷ 0.25 m² × 10,000 = 20,000 kg/ha of green forage; at 20% dry matter that is 4,000 kg DM/ha. On a 2 ha paddock with 50% utilisation, 4,000 kg DM is usable. Twenty 400 kg cattle eating 2.5% of body weight need 200 kg DM/day, so the paddock lasts 20.0 days.
Sources: Alabama Cooperative Extension — Measuring forage mass to adjust stocking rate · NC State Extension — Quantifying pasture productivity
Frequently asked questions
How many samples should I clip?
At least 10 per paddock, more in uneven pastures. Throw the frame without looking so you do not favour good or bad patches, and clip at the height the animals will graze down to (usually 5–10 cm above the ground).
How do I measure dry matter at home?
Weigh about 100 g of fresh forage, dry it in a microwave in short bursts (with a cup of water inside) or in an oven at 60–100 °C until the weight stops dropping, then divide dry weight by fresh weight.
Why use only 50% of the forage?
Grazing below that leaves too little leaf for regrowth, weakens the roots and invites weeds. Rotational systems often take 50–60%, continuous grazing 30–40%.
How much do cattle eat per day?
Beef cattle eat about 2–2.5% of body weight as dry matter, lactating dairy cows 3–4%. Sheep and goats eat around 3–4%.
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This calculator is for educational purposes. Double-check important results before acting on them.