Emergency Preparedness Calculators

Water, food, power, heat and pack weight. 9 calculators for household preparedness. Off-grid living sits under Homesteading.

Water storage comes first for a plain reason: three weeks without food is survivable, three days without water is not, and less than that in heat or while working. The base figure is one gallon per person per day for drinking and minimal hygiene, rising to 1.6 gallons in hot conditions indoors and 2.1 in extreme heat or hard labour. Children and nursing mothers add half again. Pets are the easiest thing to forget, and a large dog wants around 1.5 litres a day.

Generator fuel works from actual load rather than rated capacity, which is where published runtimes come apart. Makers quote at 50% load. A 3,500 watt petrol generator running 1,750 watts burns roughly 0.58 litres an hour, so a 15 litre tank gives about 26 hours of running. Push it near capacity and that figure falls away quickly.

Petrol keeps 6 to 12 months treated, diesel 12 to 24. Rotate it on a date, not on a feeling.