This calculator was originally written for cloth nappy (diaper) users, in the UK. The values it works out will work for any washing machine user, though, working in any decimalised currency, assuming an inflation profile similar to the UK when assessing wear & tear costs. Your electricity or gas metres may not measure in relevant units, however; there are some notes below to help resolve that.
Not everyone uses fabric conditioner, sterilising powder, etc. Set these values to zero
A 30 degree C wash uses about 40% less energy (according to most Internet sources) than a 40 degree C wash (your washing machine manual may only tell you about energy usage for 40 degree washes). For instance, our machine uses 0.65 kWh for a 40 deg. wash, so about 0.39 kWh for a 30 deg. wash. Otherwise, where nappies are washed at 60 deg. C, the costs calculator assumes that a 60 deg. wash uses 266% more energy than a 30 deg. wash, or 160% more than a 40 deg. wash
That said, pence cost per unit (kWh) of electricity is about 10p in the UK (2010 price), but likely to rise fast. Going from 40 degrees to 30 degrees therefore saves a mere 2.6 pence in energy costs, for most people.
The best detergent price I can get is about 10pence/wash (year = 2010).
You need to enter zeros for stuff that doesn't apply (like if you never use fabric conditioner).
The nappy questions are asking how often you need to wash nappies for each child -- so even if you have 2 children at once in nappies, you need to guestimate how often you would run the washing machine if only one was in cloth nappies.
Also assumed that each child in cloth for 2.5 yrs of their life. There is no facility to include tumble drying in this calculator, but you can easily figure it out by inputting the energy values as for a washing machine, and setting other variables (eg, for detergent) to zero.
Costs are in today's money (eg, year 2001).