Rested experience in classic WoW is a pool that doubles kill experience until spent; it is 5% of a level per 8 hours logged out in an inn, up to 150%.
rested: kill experience is doubled until the rested pool is spent (quests are not doubled)
the pool grows at 5% of a level per 8 hours logged out in an inn or a capital city, up to 150% of a level
logged out anywhere else: a quarter of that rate
logged in and resting in an inn: the same rate as logged out there
Log out in an inn and come back a day later with 15% of a level in the pool; a full pool of a level and a half takes ten days. The pool is spent as you kill, two experience for one.
| Logged out in an inn for 24 hours | 3 × 5% = 15% of a level rested |
| Logged out in the field for 24 hours | 15% / 4 = 3.75% of a level |
| A level that needs 40,000 XP, with 15% rested | a 6,000-XP pool: the first 6,000 XP of kill experience count as 12,000 |
Last checked: unverified against Forever. These are the long-established values of the classic ruleset (the 1.x game of 2005-2006); World of Warcraft Forever is in beta and may differ. When you test this one in Forever, post your numbers in Theorycraft.