This has been posted before but it may be helpful to repeat for this season.
MEASURING REMAINING FUEL IN CANISTERS:
1. AT HOME> Float FULL canister in water & mark the waterline on canister. (Be sure to tilt the canister when putting it in the water to evacuate all air from the concave bottom.)
2. ON THE TRAIL> Repeat the procedure in #1 and mark the canister. Doing this daily will let you know if you need to ration fuel use toward the end of the trip.

