In reply to mike123:
Assuming stove is in good working condition; no yellow flame, and well shielded from wind. Plus the water is not near freezing.
100-150ml per day; Careful, all needed water measured out. Two cups of hot drinks per day per person. Porridge breakfast, cuppa soup starter, quick cook pasta and simple sauce, with may be a quick fry of some onions or chorizo. Will still have a bit of fuel left over (more if the water is warm to start with). In summer I quite often just take a 300ml bottle for two, for a standard w/e i.e only one evening meal, but two breakfasts and have a bit of fuel left over.
200-250ml per day; Three cups per day per person, porridge breakfast left to soak post boiling water added ~ not simmered, cuppa soup, main includes some proper cooking needing boiling and then simmering for 5-10minutes, possibly second pan of water for pasta, possibly quick hot dessert, and a small flask.
300ml per day; as above but mugs rather than cups includes large 1 litre hot flask, possibly extra hot drink. Less need to be careful on measuring water quantities. I can normally just manage with a 550ml bottle in winter with water just above freezing for a standard w/e.
As soon as the stove is sub par, effected by wind, you boil too much water at each event, or there are ice crystals in the water the calculations become tight.
Post edited at 23:22