Estimate the cost per cup of your coffee maker.
Home brewed coffee costs almost nothing per cup, and the arithmetic shows why so clearly that it explains the entire coffee shop margin. At the widely used ratio of 15 g per 250 ml cup, a kilogram of beans yields about 67 cups, so even a twenty-four dollar specialty bag works out at thirty-six cents of coffee per cup. Electricity is smaller still: a drip machine uses roughly 80-120 Wh per brew cycle, under three cents. The dose is the lever that matters — moving from 15 g to 20 g per cup raises the coffee cost by a third, which is exactly the difference between a standard and a strong brew.
Brewed coffee cost per cup
Coffee cost per cup = cost per kg x grams per cup / 1000; energy cost per cup = brew Wh / 1000 x electricity rate; cost per cup = coffee + energy; cups per kilogram = 1000 / grams per cup
About 67 at a 15 g dose, or 50 at 20 g. If a bag is disappearing faster than that, your dose is heavier than you think — weigh it once and you will usually find it.
More than the brewing does. A warming plate draws 50-100 W continuously, so leaving it on for two hours can double the energy cost of the pot — and it ruins the coffee. A vacuum flask is better on both counts.
Because you are paying for rent, labour, milk and equipment, not coffee. The beans in a four dollar latte cost around thirty to fifty cents, which is the same figure this calculator produces.