Looked and looked, can't find the answer anywhere (maybe I'm blind):
How long does Alchemist's Fire burn for?
In the item description within the Adventuring Gear section of the rules, it says:
On a hit, the target takes 1d4 fire damage at the start of each of its turns. A creature can end this damage by using its action to make a DC 10 Dexterity check to extinguish the flames.
Yet no mention of the burn rate. One round after a hit? 2? A minute? Continuous until extinguished?