For those wondering about "how much fuel do I need", I'll give you my last trip's stats. I use a PocketRocket2, and a 220gr Coleman canister (I believe these are 70% butane/30% propane, but I'm having trouble confirming that). The temps were generally 40-50F while I was using the stove. My elevation was all less than 1000' MSL. I heated water to not quite boiling for 8 dinners (8-16oz each), 9 breakfasts (6-12oz each), 3 desserts (4-6oz each), and approximately 136 oz for coffee/hot chocolate. I used 113 gr of fuel.
And, as always, keep in mind that YMMV.
that's REALLY pretty good.
however which size can exactly you used (large or small) can be sometimes confusing, but I'm assuming the large can.
I only say this because small can weighs right around 200gr +/-, but the fuel content is only 100gr, whereas the larger can has 220grams of fuel, but that's not the total weight of can+fuel.
The fact that you used 113gr of fuel, tells me the larger can (since the small can only has 100gr of fuel)
Anyhoo...That's pretty outstanding you only used a little more than half a can, WOW! Terrific management.
I'd caveat this anyway, I don't think folks should assume they can run out and get 10-15 days off 1 large can.
but good job anyway
@Philreedshikes Yes, the canister is the one that contains 220gr of fuel. To be honest, where I live it is next to impossible to buy the smaller ones, I've probably seen the bigger (440 gr?) ones as much as I have the smaller ones. And, also unfortunately, about the only place near me that carries them is the big w-mart, and they only carry Coleman, and only in the 220gr size. So I always take that size canister, although I may take one that's half full or whatever I need, and I have an adapter to transfer partial cans. Keep in mind that I never "boil" water, just get it close to boiling.
@Philreedshikes It was actually 10 days, I just skipped a couple of meals. It was the River To River Trail in Shawnee Nat'l Forest in southern Illinois. 157 official miles, my iphone said I walked 173 miles and climbed 414 floors.
Thanks for reporting your stats! I agree with @Philreedshikes, you did a great job managing your fuel. As I read these posts I realize that one of the biggest examples of 'packing your fears' for me is fuel. I always take a full fuel canister on my trips, sometimes as a backup to a partial canister, but always a full one...even on a simple overnight trip. You're giving me the courage to cut down on those unnecessary things!
@REI-JohnJ I took a full one on this trip, figuring it would be close to empty when I got back. I was surprised to only use half of it. I usually take 50% more than I think I'll need, but I really missed my guess on this one. If it had been a few degrees cooler or more windy then I probably would have been closer, wind in particular seems to be hard on fuel usage.
MSR claims 1oz/28g of fuel will boil 2 liters of water for the PR2 although they don't give an altitude for that figure. In theory you will use less fuel to boil at altitude since the boiling point is lower but you may use more fuel if you need to "cook" (ie simmer) since the lower boiling temp means things take longer to cook.
But based on MSR's number you can boil 2(227/28) ~ 16 liters of water with 227g of MSR fuel. If each drink or freeze dried meal takes 333ml (11floz) average of water that is (16000/333) ~ 48 drinks/meals. If you have, say, 4 a day then that's theoretically (48/4) ~ 12 days from an MSR 227g can using the PR2.
The stove you use, how you use it and how windy and cold it is where you use the stove will change the numbers.
Note: The brand/fuel mix you use may make some difference by I suspect not that much based on the testing I have found...at least until you get down to around freezing where some mixes will work and other won't without some warming of the can. A trick is to warm the canister with your body (eg keep it in your sleeping bag) to get it going and then place the canister in a dish of liquid (warm not hot) water while running the stove. Pure Butane boils at ~ 0C/32F and the best IsoButane/Propane mixes can apparently get you down to ~ -7C/20F. You have to move to an inverted canister stove to go lower (apparently ~ -18C/0F) and move to a different type of stove to go lower than that (eg: white gas) .