Wattage × hours × rate — see your daily and monthly cost.
Air conditioner 1–3 kW · Water heater 2–3 kW · Fridge 100–200 W · TV 80–150 W · Laptop 50–100 W · LED bulb 5–15 W
Energy (kWh) = power (W) × hours ÷ 1000. Cost = kWh × your rate. Example: a 2,000 W heater used 3 h/day ≈ 6 kWh/day ≈ ¥100.80/month at ¥0.56/kWh.