Calculate the ideal paddock size for rotational grazing based on herd size, forage yield, rest period, and utilization rate. Free paddock planner.
The Rotational Grazing Paddock Size Calculator determines the optimal acreage for each paddock in a rotationally grazed system. Proper paddock sizing ensures animals have adequate forage during each grazing period while allowing sufficient rest for pasture recovery between grazings.
The calculation balances herd forage demand (head × daily intake × grazing period days) against available forage per acre adjusted for utilization rate. The key insight is that each paddock must supply enough forage for the herd during the entire grazing bout on that paddock, and the total number of paddocks must allow adequate rest before re-grazing.
Well-designed rotational grazing systems improve pasture productivity by 25-50% compared to continuous grazing. They allow range managers to control utilization, promote root recovery, distribute manure more evenly, and manage weed pressure. This calculator helps you plan the paddock infrastructure — number and size of paddocks — that makes these benefits achievable. Whether you are a beginner or experienced professional, this free online tool provides instant, reliable results without manual computation.
Properly sized paddocks are the foundation of any rotational grazing system. Paddocks that are too large lead to over-utilization in preferred areas and under-utilization elsewhere. Paddocks that are too small don’t provide enough forage for the herd, requiring premature moves. This calculator optimizes your layout for animal performance and pasture health.
Paddock size (ac) = (Head AU × DMI/day × Grazing days) / (Forage/ac × Utilization%) Total paddocks = (Rest days / Grazing days) + 1 Where: Head AU = Total animal units in the herd DMI/day = Daily dry-matter intake per AU Grazing days = Days on each paddock before moving Forage/ac = Standing forage in lbs DM per acre Utilization% = Target harvest fraction Rest days = Days of rest between grazings
Result: 3.9 acres per paddock, 11 paddocks needed
Forage demand per paddock = 50 × 26 × 3 = 3,900 lbs DM. Usable forage per acre = 2,000 × 0.50 = 1,000 lbs. Paddock size = 3,900 / 1,000 = 3.9 acres. Total paddocks = (30 / 3) + 1 = 11.
Correctly sized paddocks ensure uniform utilization — animals harvest available forage evenly rather than overgrazing favorites and ignoring less palatable species. This promotes diverse, healthy plant communities and more productive pastures over time.
Before subdividing, map your pasture and plan water access, lanes, and handling facilities. Every paddock needs water within a reasonable walking distance. Lanes connecting paddocks to water and corrals should be wide enough for easy livestock movement and equipment access.
The calculator provides a starting point, but real-world grazing management is adaptive. Monitor forage conditions, animal performance, and weather forecasts. Be prepared to lengthen or shorten grazing periods, combine or split paddocks, and adjust stocking rate as conditions dictate. Flexibility is the hallmark of successful grazing management.
Rest periods of 25-45 days are typical for cool-season grasses during the growing season. Warm-season grasses may need 30-60 days. During drought or dormancy, extend rest periods further or defer grazing entirely.
Shorter is generally better for forage recovery. High-performance rotational systems use 1-3 day grazing periods. Longer periods (5-7 days) are acceptable for lower-intensity rotational grazing systems.
With temporary electric fencing, you can adjust paddock size in real-time. During flush spring growth, you may graze larger areas or skip paddocks. During slow growth, reduce paddock size to maintain grazing pressure and prevent waste.
For rotational grazing, 40-60% utilization is typical. Higher utilization is acceptable because the rest period allows full recovery. On native rangeland under rotation, stay closer to 40%. On improved pastures, 50-60% is achievable.
A combination works best. Permanent perimeter fencing and permanent lanes for water and handling, with temporary electric cross-fencing for paddock divisions. This minimizes cost while maximizing flexibility.
Mob grazing uses very high stock density (50,000+ lbs/ac) for very short periods (hours to 1 day) with long rest periods (60-90 days). It requires many more paddocks and more frequent moves but can dramatically improve soil health.