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About the OSRS Prayer Calculator
Work out how many bones or ashes you need for a Prayer goal, what they cost and how long it takes. Methods include burying, the gilded altar, the Chaos Altar, the Ectofuntus, the libation bowl and the Arceuus offering spells.
How to use the OSRS Prayer Calculator
- Enter your current Prayer level or exact XP, and a target. The milestone buttons jump to Piety, Rigour, Augury and 99.
- Pick a bone or ash.
- Pick a method. Only methods that fit that bone or ash are shown.
- Read the count, the approximate cost and time. For the Chaos Altar the worst case with no saved bones is shown too.
How the numbers are worked out
- A gilded altar with both burners lit gives 3.5× bury XP: 252 for a dragon bone.
- The Chaos Altar also gives 3.5× per offering, and each offering has a 50% chance not to use the bone. On average each bone used is worth 7× (504 for a dragon bone). The count shown is that average.
- The Ectofuntus gives 4×. Sinister and Demonic Offering give 3×. The libation bowl gives 5 or 6 XP per blessed bone shard.
- Cost is bones at GE prices plus fees: 50 coins per bone to un-note at the Elder Chaos druid and 10 coins at Virilis for the libation bowl.
- Time uses the wiki's rates, such as 2,550 bones offered an hour at a gilded altar and about 2,000 offerings an hour at the Chaos Altar when you suicide for each inventory.
Frequently asked questions
How many dragon bones for 99 Prayer?
From level 1, 51,724 dragon bones at a gilded altar (252 XP each). At the Chaos Altar the average is 25,862, because half the offerings keep the bone.
Is the Chaos Altar faster than a gilded altar?
It depends on how you bring the bones. If you die for each new inventory, no: the wiki puts the Chaos Altar at about 500k XP an hour with dragon bones, against about 643k at a gilded altar. With noted bones it reaches about 860k an hour, but you can lose them to player killers. Either way the Chaos Altar uses about half the bones for the same XP.
Why does the Chaos Altar show a worst case?
The 50% save is an average. With bad luck you use more bones, and the worst case assumes no offering is saved.
Does the cost include un-noting fees?
Yes. The Chaos Altar adds 50 coins per bone for the Elder Chaos druid, and the libation bowl adds 10 coins per bone for Virilis, plus the wine and splinters it uses.
What level do I need for Piety, Rigour and Augury?
Piety needs 70 Prayer, Rigour 74 and Augury 77. The milestone buttons set those targets for you.
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