FlipFuel® allows you to transfer fuel from one canister to another. Consolidate partially empty canisters into one full one for longer trips, or portion off only the fuel you need into a smaller canister for shorter trips.
An efficient stove like the only uses about 1/4 ounce (7 grams) of fuel per 2-cup boil. There is no point of carrying significantly more fuel than you need for your trip!
Weigh your canisters when you first buy them and write the full-weight on the can. Then you can calculate the weight of the canister itself and know how much fuel is remaining.
Before transferring fuel, place the receiving canister in a freezer for several minutes to shrink the contents, and place the giving canister in the sun to expand the contents.