How the Herb Run Profit Calculator works
Harvest lives, the chance-to-save formula with every boost, the disease model and the money, with a worked example at level 99.
1. Chance to save a harvest life
pSave = (1 + floor(CTS′low × (99 − F) / 98 + CTS′high × (F − 1) / 98 + 0.5)) / 256
F is your Farming level (1–99). CTS_low is the herb's constant at level 1 and CTS_high = 80 for every herb, so at 99 all herbs yield the same. item is 0.10 for magic secateurs, 0.05 for the Farming or Max cape, 0.15 for both. diary is +10 / +17 / +25 at Catherby for the medium / hard / elite Kandarin diary and +10 at Hosidius and the Farming Guild for the hard Kourend & Kebos diary. Boosts are applied in the order item → diary → attas to both constants before the level interpolation.
2. Expected herbs from a living patch
Each pick either uses a life or not, so the number of herbs is negative-binomial with the lives as the number of failures; the mean is lives ÷ (1 − pSave). The minimum harvest is the number of lives.
3. Disease and death
survive = (1 − perCycle)³ 1 for disease-free patches
That gives 27, 14, 6 and 3 chances in 128 per growth cycle; with iasor 6, 3, 2 and 1. Herbs can be diseased at the end of three of their four cycles, and an untreated diseased herb dies. Troll Stronghold, Weiss and Harmony Island patches are immune; Hosidius becomes immune with the easy Kourend & Kebos diary, Civitas illa Fortis at Colosseum champion rank.
4. Money and XP per run
revenue = herbsRun × (grimyPrice − tax) tax = floor(0.02 × price), 0 under 50 gp, optional
cost = patches × (seedPrice + compostPrice × bucket) bucket = 0.5 with the bottomless compost bucket
profit = revenue − cost
xp = patches × plantXp + herbsRun × herbXp
Seeds and compost are priced at the Grand Exchange instant-buy price, grimy herbs at the instant-sell price. Dead patches still pay for the seed and compost. Cleaning XP, teleport costs and the time of the run are not included.
Worked example
Level 99, ultracompost, magic secateurs, no cape, no diaries: CTS′ = floor(80 × 1.1) = 88 → pSave = (1 + 88) / 256 = 34.77%. Expected herbs from a living patch = 6 / (1 − 0.3477) = 9.20. Survival with ultracompost = (125 / 128)³ = 93.1%, so an ordinary patch gives 8.56 herbs on average and a disease-free patch 9.20. Nine patches (three of them disease-free) ≈ 79.0 herbs per run.
Constants used
| Herb | Level | Plant XP | XP per herb | CTS at 1 | CTS at 99 |
|---|---|---|---|---|---|
| Guam | 9 | 11 | 12.5 | 25 | 80 |
| Marrentill | 14 | 13.5 | 15 | 28 | 80 |
| Tarromin | 19 | 16 | 18 | 31 | 80 |
| Harralander | 26 | 21.5 | 24 | 36 | 80 |
| Ranarr | 32 | 27 | 30.5 | 39 | 80 |
| Toadflax | 38 | 34 | 38.5 | 43 | 80 |
| Irit | 44 | 43 | 48.5 | 46 | 80 |
| Avantoe | 50 | 54.5 | 61.5 | 50 | 80 |
| Kwuarm | 56 | 69 | 78 | 54 | 80 |
| Snapdragon | 62 | 87.5 | 98.5 | 57 | 80 |
| Huasca Level-1 chance-to-save constant not published; 59 is interpolated between snapdragon and cadantine. Exact at level 99. | 65 | 86.5 | 110 | 59 | 80 |
| Cadantine | 67 | 106.5 | 120 | 60 | 80 |
| Lantadyme | 73 | 134.5 | 151.5 | 64 | 80 |
| Dwarf weed | 79 | 170.5 | 192 | 67 | 80 |
| Torstol | 85 | 199.5 | 224.5 | 71 | 80 |
| Compost | Lives | Disease / cycle | Survive 3 cycles |
|---|---|---|---|
| No compost | 3 | 27/128 | 49.1% |
| Compost | 4 | 14/128 | 70.6% |
| Supercompost | 5 | 6/128 | 86.6% |
| Ultracompost | 6 | 3/128 | 93.1% |
Patches: Ardougne, Catherby, Falador, Farming Guild, Hosidius, Port Phasmatys, Troll Stronghold, Weiss, Harmony Island, Civitas illa Fortis.
Sources
- Chance-to-save formula, boost order and lives per compost: OSRS Wiki, Farming → Variable crop yield (Mod Ash and Mod Kieren statements cited there). Checked 12 November 2026.
- Disease per cycle and the three at-risk cycles: OSRS Wiki, Disease (Farming).
- Levels and XP: in-game values as listed for each herb seed. Prices: prices.runescape.wiki real-time API.
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