Rex says
Everyday utility math — the kind you'd otherwise pull up four browser tabs for. I keep it to one clean answer.
Try a scenario
Click to load — tweak from there.Inputs
Result
Paddocks needed
13
Acres per paddock
9.2
Full rotation cycle length
39
Stock density during grazing
32.5
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How to use this
- 1Enter total grazing acres.
- 2Enter target rest period (days).
- 3Enter grazing period per paddock (days).
- 4Enter head in the rotation.
- 5Read your paddocks needed on the right — it updates as you type.
- 6Hit Share to keep the scenario or send it to someone.
About this calculator
Rotational grazing works because rest periods let grass rebuild root reserves and leaf area after defoliation, but too few paddocks force you back onto grass before it's recovered, defeating the purpose. This calculator takes your target rest period (which should track regrowth speed — faster in spring, slower in summer heat or drought) and your grazing period per paddock to compute how many paddocks a rotation needs, then converts that into total acres per paddock given herd size and stocking density. Most well-designed rotational systems need at least 8-12 paddocks to hit meaningful rest periods without grazing periods that are so long they allow regrazing of the same regrowth.
Worked example
Using the values the calculator loads with:
Inputs
- Total grazing acres: 120
- Target rest period: 35 days
- Grazing period per paddock: 3 days
- Head in the rotation: 100
Results
- Paddocks needed: 13
- Acres per paddock: 9.2
- Full rotation cycle length: 39
- Stock density during grazing: 32.5
What each field means
Inputs
- Total grazing acres
- The total grazing acres used in the calculation. Starts at 120 so you have a working example on load.
- Target rest period (days)
- The target rest period used in the calculation, measured in days. Starts at 35 days so you have a working example on load. Accepted range: 10–90 days.
- Grazing period per paddock (days)
- The grazing period per paddock used in the calculation, measured in days. Starts at 3 days so you have a working example on load. Accepted range: 1–14 days.
- Head in the rotation
- The head in the rotation used in the calculation. Starts at 100 so you have a working example on load.
Results
- Paddocks needed
- Returned as a whole number and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Acres per paddock
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Full rotation cycle length
- Returned as a whole number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Stock density during grazing
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
How long should rest periods be?
Spring flush regrowth can support 18-25 day rests, while summer slump and drought conditions often need 45-60+ days for the same recovery. Watching the grass, specifically new leaf regrowth reaching the 3-leaf stage, is more reliable than a fixed calendar number.
Why not just use fewer, bigger paddocks?
Fewer paddocks force either shorter rest (grass doesn't fully recover) or longer grazing periods per paddock (cattle regraze the same regrowth, which is the most damaging pattern for plant vigor). More paddocks let you keep grazing periods short while still hitting the target rest.
What's a practical minimum number of paddocks to start with?
Most graziers see meaningful improvement moving from continuous grazing to just 4-6 paddocks, but 8-12+ is where you start reliably matching rest periods to actual regrowth rates across a full season without constant fence-moving fatigue.
Does stock density during grazing matter beyond paddock count?
Yes — higher stock density for a shorter time improves grazing distribution and manure spread compared to low density for a long time, even at the same total animal-days per acre. This is the core lever in high-intensity, short-duration systems like mob grazing.
Accuracy and limitations
- Estimates assume standard, average conditions — local rules, pricing, and materials vary.
- Results are rounded for readability; add a buffer before ordering, booking, or committing.
- Double-check anything with a real cost attached against a local quote.
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Hay Bale Cost Per Ton Calculator
Compare round and square bale pricing on an apples-to-apples ton basis.
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Pasture Rest & Rotation Planner. Retrieved from https://www.revenuelab.fyi/toolbox/pasture-rest-rotation
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/pasture-rest-rotation" target="_blank" rel="noopener">Pasture Rest & Rotation Planner — RevenueLab</a> (2026).</p>
Source: [Pasture Rest & Rotation Planner — RevenueLab](https://www.revenuelab.fyi/toolbox/pasture-rest-rotation) (2026).