Suppose a meter or manufacturer document gives 0.12 kWh for one complete use. There is one device, one use per day, a 30-day period, and a flat rate of 0.22 in the selected currency per kWh. Known-energy mode skips the power-and-time estimate and starts from that cycle value.
Multiply measured energy by frequency
Energy per day is 0.12 × 1 = 0.12 kWh. For 30 days, 0.12 × 30 = 3.6 kWh. At 0.22 per kWh, the 30-day cost is 3.6 × 0.22 = 0.792 in the selected currency. The currency code labels the result; it does not convert exchange rates.
Treat the annual number as a baseline
At the same daily frequency, 365 days gives 43.8 kWh and 9.636 in the selected currency. This is useful for comparing devices or habits under one consistent assumption. If frequency, measured cycle energy, or tariff changes by season, calculate separate periods instead of treating one annual projection as a bill forecast.