Best way to farm Giant bat wing

Items per hour = kills per hour × average items per kill.

Average items per kill adds up every drop line as the wiki shows it (rarity × average quantity × rolls), so a guaranteed drop plus a rarer bonus drop both count. Drop rates and quantities come from the OSRS Wiki's drop tables; rates marked ~ are approximate on the wiki. "via" means the item comes inside another drop, like red spiders' eggs in Sarachnis's giant egg sac.

Kill times are estimates, worked out the same way for every monster from its hitpoints and defence. Add your RuneScape name in Preferences and they're worked out from your own combat levels instead. We can't see your gear or include boss mechanics, so expect individual times to be off; what matters is how the monsters compare. You can type your own time for any monster: it's remembered on this device for every page (↺ goes back to the default), and shared anonymously to help improve the estimates (privacy).

Achievement diaries that improve a drop rate or quantity can be ticked in Preferences.