OSRS CoX Calculator
Your purple chance in the Chambers of Xeric at your points and your team's, the raids a twisted bow takes, how dry you are and what a raid is worth.
Both totals show in the raid's points box. A solo raid with no deaths is about 30,000 points, a solo Challenge Mode about 62,000.
Your chance of each unique
The team's points roll for a unique, and each one goes to a player drawn in proportion to points.
| Unique | A raid | On average | Half get it by | Sells for | Adds to a raid |
|---|
How long until it drops
Every points total, side by side
Your own points down the side, with the team scoring the same share of the total.
| Your points | Team points | Your purple | 1 in | Twisted bow, 1 in | A raid is worth |
|---|
The unique rolls
Every 570,000 of the team's points is one roll at 65.7%, and the rest is one more, up to six.
| Roll | Team points | Hits | Yours |
|---|
The other rewards
Rolled for you alone.
The common loot
| Item | A roll | You get | Sells for |
|---|
How lucky you have been
Use the points the raid shows you. The team's points decide the chance of a unique, and your share of them decides who gets it. A death costs a player 40% of their points. Loot is priced at what it sells for right now, after the 2% tax. A player given a unique gets no common loot, and a raid's worth counts that. The Olmlet, the colour kit, metamorphic dust, the dark relic and clue scrolls cannot be sold, so they are counted and never priced. Figures checked against the OSRS Wiki on 19 October 2026.
How the purple chance works
Everything a team does in the Chambers earns points: damage, cooking food that others eat, potions, the puzzle rooms. When the Great Olm dies the game rolls for a unique on the team's total: 1% for every 8,676 points, so 30,000 points is 3.46% and 1 raid in 28.9. The chance stops at 65.7%, which takes 570,000 points; anything past that rolls for a second unique on the same terms, and so on up to six. A team of 855,000 points has a 65.7% roll and a 32.85% roll.
Each unique goes to one player, drawn by points, so your chance is the team's times your share. Scaling a raid with more players raises the team's total, while your share of it shrinks.
Which unique you get
Once a unique is rolled, the item is drawn by weight. In normal mode the weights add to 60 and in Challenge Mode to 56, because Challenge Mode has fewer prayer scrolls. A twisted bow is 1 purple in 30 in normal mode and 1 in 28 in Challenge Mode.
| Unique | Weight | Normal, 1 purple in | CM weight | Challenge Mode, 1 in |
|---|---|---|---|---|
| Dexterous prayer scroll | 14 | 4.29 | 12 | 4.67 |
| Arcane prayer scroll | 14 | 4.29 | 12 | 4.67 |
| Twisted buckler | 4 | 15 | 4 | 14 |
| Dragon hunter crossbow | 4 | 15 | 4 | 14 |
| Dinh's bulwark | 3 | 20 | 3 | 18.67 |
| Ancestral hat | 4 | 15 | 4 | 14 |
| Ancestral robe top | 4 | 15 | 4 | 14 |
| Ancestral robe bottom | 4 | 15 | 4 | 14 |
| Dragon claws | 3 | 20 | 3 | 18.67 |
| Elder maul | 2 | 30 | 2 | 28 |
| Kodai insignia | 2 | 30 | 2 | 28 |
| Twisted bow | 2 | 30 | 2 | 28 |
What the common loot is
A player with no unique makes two rolls on the common table, and the two are never the same item. Each roll is 1 in 33 for most entries: runes, arrows, ores, gems, planks, dynamite and the rest. A herb's slot drops the herb two times in three and its seed one time in three. How much you get is your points over a number fixed for that item, so a death room or a slow raid shows up in the loot as well as in the purple chance. Common loot stops growing at 131,071 of your points.
Challenge Mode
Challenge Mode has every room and tougher monsters, so a raid takes longer and earns far more points. Finished inside the time limit for the team size, it adds 5,000 points for each player to the team's total and rolls for a twisted ancestral colour kit (1 in 75) and metamorphic dust (1 in 400) on top of everything else.
| Players | Time limit |
|---|---|
| 1 | 1 hour 10 minutes |
| 2 | 1 hour 5 minutes |
| 3 | 50 minutes |
| 4 | 45 minutes |
| 5 to 10 | 42 minutes |
| 11 to 15 | 45 minutes |
| 16 to 23 | 1 hour |
| 24 or more | 1 hour 20 minutes |
CoX questions
Points per raid or points per hour? Per hour, for drops over time: a quicker raid with fewer points can still give more purples an hour. The stats above take your minutes a raid, and the side by side table shows how the chance moves with points.
Do deaths matter? A death takes 40% of that player's points. A player who dies with almost no points costs the team 5% of its total instead.
How long does a twisted bow take? Pick it as the drop you are after and the page gives the raids and hours for half, three quarters, nine in ten and 99 in 100 players.
What about the other raids? The ToA calculator does the same for the Tombs of Amascut, and the dry calculator covers every other boss.
Update history
Every change to this calculator
- Calculator added