Work out roughly how many days your LPG will last based on real-world consumption rates for cooking, hot water and heating.
LPG has an energy content of roughly 26MJ per kg. These consumption profiles are typical real-world averages for a 2-adult caravan, but actual use varies with burner size, hot water system efficiency, climate and how careful you are - use this as a trip-planning guide, not an exact fuel gauge, and always carry a spare bottle. For your full daily power picture, see the Daily Power Usage Calculator.