XP Calcs
Boss and skilling pet ledger

OSRS Pet Chance Calculator

Choose a boss or skilling-pet source, enter completed eligible rolls, and calculate the cumulative pet chance. The base-rate table keeps every denominator and level adjustment visible.

Choose a pet source

Chance of Vorki

63.22%

Effective rate: 1 / 3,000

About 2,080 kills

to pass a 50% cumulative chance.

Pet base-rate ledger

One row equals one eligible reward roll. Level-adjusted rows subtract 25 per skill level from the listed base denominator.

PetSourceTypeBase rate
VorkiVorkathBoss1 / 3,000
Pet krakenKrakenBoss1 / 3,000
Abyssal orphanAbyssal SireBoss1 / 2,560
PhoenixWintertodt supply crateSkilling1 / 5,000
Tiny temporTempoross reward permitSkilling1 / 8,000
HerbiHerbiboar harvestSkilling1 / 6,500
RockyArdougne knight pickpocketSkilling1 / 257,211 − 25 × level
BeaverRedwood logSkilling1 / 72,321 − 25 × level

How it works

The pet chance calculator uses the complement of repeated failure. Boss entries have a fixed probability on each eligible kill or reward roll. Rocky from an Ardougne knight pickpocket and Beaver from a redwood log use the published skilling-pet form: subtract 25 times the relevant skill level from the source’s base denominator before compounding attempts. Supply crates, reward permits and Herbiboar harvests count as rolls, not full games or catches. The table deliberately avoids pets whose exact chance needs extra inputs such as contribution points. Duplicate pets are possible, but the output asks only whether at least one pet arrived. A dry streak never improves the next independent roll unless a specific source has an explicit protection mechanic, which none of the listed rows use.

d=base−(skill level×25)(when applicable)P(pet by n rolls)=1−(1−1d)n\begin{aligned} d &= \text{base} - (\text{skill level} \times 25) \quad \text{(when applicable)} \\ P(\text{pet by } n \text{ rolls}) &= 1 - \left( 1 - \frac{1}{d} \right)^n \end{aligned}
Inputs are kept at full precision. Discrete counts round up when a partial action cannot complete the goal; probabilities and rates keep their fractional meaning.

Worked example

Vorki has a listed 1 in 3,000 eligible-kill rate. Across 3,000 independent Vorkath kills, the chance of at least one Vorki is about 63.22%, while the chance of receiving none is about 36.78%. The cumulative chance passes 50% at 2,080 kills.

Interpreting the result

Start by checking that each field describes the same scenario as the result: levels are visible base levels, bonuses are entered separately, costs are per unit, and a one-in-X rate means one divided by X on each eligible roll. The calculator updates immediately and writes the complete input state into the address bar. “Copy link” preserves those assumptions; “Copy result” copies a short summary rather than the entire method.

Do not treat a rounded count as an hourly rate. A required-action total says how many successful units complete the target under the entered reward. Banking, movement, failed attempts, animation timing, missed ticks and setup changes affect elapsed time. When time matters, measure a representative session with the same method and divide the required count by the observed successful actions per hour.

Economic outputs are arithmetic scenarios rather than live market quotations. Check current item values before buying supplies, include any outputs that can be sold, and consider limits or low-volume price movement. Probability outputs describe repeated independent trials; they do not promise that a result arrives at the displayed attempt count. The visible formula is the authority for what this page includes.

Read this as a planning estimate. Game updates, equipment effects, failures, travel, downtime and live prices can move a real session away from the mathematical result. Check the inputs against the account and use the output as a reproducible baseline.

Questions about OSRS Pet Chance Calculator

What is my OSRS pet chance at the listed drop rate?
Select the exact source and enter eligible kills or actions. The result compounds every independent roll rather than multiplying the rate by attempts.
Why is the chance near 63% at the drop-rate denominator?
Repeating a 1/d chance d times leaves about a 36.8% chance of no success, so the complementary chance is about 63.2%, not 100%.
Does skill level change every skilling pet rate?
No. Only rows marked with the level adjustment use base denominator minus 25 times skill level. Other listed reward rolls use their fixed denominator.
Do unsuccessful kills make the next pet roll more likely?
No. The listed sources use independent rolls, so previous failures do not change the next eligible roll.

Sources

Mechanics and fixed tables were reviewed in 2026. Price-like inputs are user-controlled or approximate rather than live quotes. Source links name the public reference used for the page; the visible formula states the exact implementation.

  1. Old School RuneScape Wiki — Pet — Boss and activity pet source rates, reviewed 2026.
  2. Old School RuneScape Wiki — Skilling pets — Level-adjusted base-chance formula and source tables, reviewed 2026.
  3. Bernoulli distribution complement — Independent-trial cumulative probability.

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