Average Farm Cover (AFC) — What It Is and How to Calculate It
Average Farm Cover is the single most important metric in rotational grazing management. It tells you how much grass your farm is carrying in total — and whether that's enough, too much or too little relative to what your herd needs each day.
Quick answer
AFC = sum of (paddock cover × paddock area) ÷ total farm area (kg DM/ha). UK dairy systems target 2,000–2,500 kg DM/ha during the main season. Irish Teagasc systems target 900–1,100 kg DM/ha. Check AFC weekly and act before it moves too far above or below target.
How to Calculate Average Farm Cover
AFC is a weighted average — larger paddocks count for more than smaller ones. The formula is straightforward:
For example, a farm with four paddocks:
| Paddock | Cover (kg DM/ha) | Area (ha) | Cover × Area |
|---|---|---|---|
| Top Field | 2,800 | 2.5 | 7,000 |
| Long Meadow | 2,200 | 3 | 6,600 |
| Triangle | 1,900 | 1.5 | 2,850 |
| Home Field | 1,600 | 3 | 4,800 |
| Total / AFC | — | 10 ha | 2125 kg DM/ha |
AFC Calculator — Enter Your Paddock Covers
2,260 kg DM/ha
Over 10.0 ha total · AFC is within target range for the main grazing season (UK dairy/beef).
Seasonal AFC Targets
Target AFC varies through the season. In early spring, lower AFC is normal as the grazing year is just starting. In summer, AFC should be maintained in the target range. In autumn, you need to plan your closing date covers carefully to set up for next spring.
| Period | UK target (kg DM/ha) | ROI target (kg DM/ha) | Action |
|---|---|---|---|
| Early spring (Feb–Mar) | 1,600–1,800 | 700–800 | Build covers before turn-out; target higher AFC to buffer slow spring growth |
| Spring (Apr–May) | 2,000–2,300 | 900–1,100 | Close surplus paddocks for silage; rotation should be lengthening |
| Early summer (Jun–Jul) | 2,000–2,500 | 900–1,100 | Maintain AFC in target range; watch for summer flush creating surplus |
| Late summer (Aug–Sep) | 2,000–2,200 | 850–1,000 | Growth slows — reduce rotation length to maintain cover quality |
| Autumn (Oct–Nov) | 1,800–2,000 | 700–900 | Plan closing date covers; target 700–800 kg DM/ha for final grazing |
| Winter (Dec–Jan) | Housed | 200–400 | ROI: maintain residual cover during mild winters for early spring growth |
Using AFC to Calculate Days of Grass Ahead
Once you have your AFC, you can calculate how many days of grass you have ahead before paddocks need to be at their post-grazing target. This is the most actionable output from your wedge measurement:
Days ahead = (AFC − post-grazing target) × total area ÷ daily herd demand
Example: AFC 2,200, post-target 1,500, 40 ha, 100 cows × 13.5 kg DM/day = (2,200 − 1,500) × 40 ÷ 1,350 = 20.7 days ahead
If days ahead equals your target rotation length, you're in balance. If it's shorter, act to reduce demand or extend recovery. If it's longer, close paddocks for silage before quality declines.
Free tool
AgriOps Grass Wedge Planner
Enter your paddock covers once and let AgriOps calculate AFC, days ahead, rotation length and your full grass wedge chart automatically. Track every measurement with a date, method and notes.
Frequently Asked Questions
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