Water Heater Efficiency CalculatorBy Admin / November 13, 2025 Water Heater Efficiency Calculator Enter any 3 values to calculate the missing variable Mass of the Water Kilograms (kg) Grams (g) Pounds (lb) Change in Temperature Celsius (°C) Kelvin (K) Fahrenheit (°F) Total Energy Input into Water Heater Joules (J) Kilojoules (kJ) Calories (cal) BTU Efficiency (%) Calculate Reset