XP Calcs
Task odds and assignment planner

OSRS Slayer Task Calculator

Choose a master and level, lock blocked tasks, then inspect probability and expected assignments for any selected task in live URL state.

Target task odds
Metal dragons
1-in-X
23

Expected assignments before this task: 23.36

Chance in 100 assignments: 98.74%

Set Slayer filters

Target-task outputs

4.2813%

Expected kills per assignment: 40.0

Expected kills in 100 assignments: 171.25

Chance within 100 assignments: 98.74%

Eligible task table

Probabilities are normalised after level and block filters.

TaskWeightProbability1-in-XExpected killsExpected kills / 100 tasks
Metal dragons144.281%23.3640.0171.25
Abyssal demons123.670%27.25165.0605.50
Boss123.670%27.2519.069.72
Dark beasts113.364%29.7315.050.46
Araxytes103.058%32.7070.0214.07
Hellhounds103.058%32.70165.0504.59
Lizardmen103.058%32.70170.0519.88
TzHaar103.058%32.70164.5503.06
Black dragons92.752%36.3315.041.28
Cave kraken92.752%36.33110.0302.75
Dagannoth92.752%36.33165.0454.13
Greater demons92.752%36.33165.0454.13
Kalphite92.752%36.33165.0454.13
Nechryael92.752%36.33165.0454.13
Smoke devils92.752%36.33165.0454.13
Aviansie82.446%40.88160.0391.44
Black demons82.446%40.88165.0403.67
Bloodveld82.446%40.88165.0403.67
Drakes82.446%40.8880.0195.72
Gargoyles82.446%40.88165.0403.67
Red dragons82.446%40.8847.5116.21
Suqahs82.446%40.8875.0183.49
Vampyres82.446%40.88155.0379.20
Warped creatures82.446%40.88165.0403.67
Wyrms82.446%40.88130.0318.04
Aberrant spectres72.141%46.71165.0353.21
Basilisks72.141%46.71165.0353.21
Fire giants72.141%46.71165.0353.21
Fossil Island wyverns72.141%46.7135.074.92
Gryphons72.141%46.71155.0331.80
Skeletal wyverns72.141%46.7130.064.22
Spiritual creatures72.141%46.71165.0353.21
Trolls61.835%54.50165.0302.75
Ankou51.529%65.4065.099.39
Aquanites51.529%65.4040.061.16
Dust devils51.529%65.40165.0252.29
Frost dragons51.529%65.4095.0145.26
Blue dragons41.223%81.75140.0171.25
Cave horrors41.223%81.75165.0201.83
Elves41.223%81.75140.0171.25
Kurask41.223%81.75165.0201.83
Mutated zygomites20.612%163.5025.015.29
Waterfiends20.612%163.50165.0100.92

How it works

Slayer task assignment is weighted random among the active pool. This page loads the public master table and applies your level and block filters before renormalising the remaining weights.

The first output is the selected task row: probability, expected number of assignments to see the task, and chance of being assigned at least once over N attempts.

Blocks are capped at six entries to match standard game behavior. A locked task is removed from the weighted pool before normalisation, then probabilities are recomputed on the remaining set.

Expected kills per assignment uses midpoint quantity in each row. Midpoint expectation helps compare short and long tasks by workload; this page also shows expected kills per 100 assignments as an extra throughput view.

Master data is snapshot-based and includes combat and Slayer requirements plus quantity ranges by task. Your level input gates out ineligible tasks first, then blocks remove entries by name, then renormalisation happens.

The sticky panel mirrors a stable 99-tick style ledger and keeps the most relevant one-in value visible while the full table below updates for all rows.

Use this page to estimate route variance before logging in: low-probability one-of tasks can take long enough that many sessions pass without seeing them.

The source data is intentionally tied to a reviewed date so differences can be checked against current wiki snapshots before you assume an assignment is impossible.

expected kills per assignment=taskmin⁡+taskmax⁡2p(task)=weighttotal eligible weightexpected assignments=1pchance in n assignments=1−(1−p)n\begin{aligned} \text{expected kills per assignment} &= \frac{\text{task}_{\min} + \text{task}_{\max}}{2} \\ p(\text{task}) &= \frac{\text{weight}}{\text{total eligible weight}} \\ \text{expected assignments} &= \frac{1}{p} \\ \text{chance in } n \text{ assignments} &= 1 - (1 - p)^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

For an eligible pool at 99 Slayer with Duradel and no blocks, if a task has 5% probability, expected assignments is 20 and chance inside 100 assignments is 99.4% approximately.

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 Slayer Task Calculator

Do blocked tasks renormalise odds?
Yes. Blocked tasks are removed first, then all probabilities are renormalised over the remaining weight pool.
Why does my task chance change with level?
Tasks above your Slayer level are removed by gate, which changes the denominator in probability calculations.
Is the one-in value a guarantee?
No. One-in-X describes expectation over many sessions, not a guaranteed number of assignments.
Can blocking all tasks break the tool?
If no tasks remain, the table is empty and the target row reports no eligible assignment.
Where do quantities come from?
Rows use midpoint from the task minimum and maximum quantity in the source table used by this build.
Can this account for quests and unlocks?
The table includes task names and base level gating. Unlock and location constraints are documented in page notes for awareness.

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 — Slayer master — Master pools, level gates, and task examples, reviewed 2026-09-05.
  2. Old School RuneScape Wiki — Duradel — Duradel task tables for source review, reviewed 2026-09-05.
  3. Old School RuneScape Wiki — Konar quo Maten — Konar pool for location and task weighting checks, reviewed 2026-09-05.
  4. Old School RuneScape Wiki — Nieve — Nieve pool for weighted task assignment checks, reviewed 2026-09-05.

Related calculators

Dry calculatorApply the same chance model language to independent reward checks.High alch calculatorSwitch from task economy to alchemy planning with the same URL state discipline.XP calculatorUse this for level targets while planning assignment-heavy sessions.Combat path calculatorPair with combat build planning if your rotation is combat-gated.

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