Home energy & HVAC calculators
BTU, AC size, HVAC tonnage, electricity and heating costs, water and pool heaters. Every tool below is free, works instantly in your browser and explains the formula behind the result.
Heating, cooling and hot water make up most of a typical home energy bill. These calculators help you size air conditioners and water heaters, estimate HVAC tonnage, and work out what appliances, space heaters and pool heaters really cost to run. They use widely published rules of thumb and sizing charts, and explain where a professional load calculation is worth getting.
21 tools in this category
- BTU to kWConvert BTU per hour to kilowatts.
- BTU to TonsConvert BTU per hour to tons of refrigeration.
- Watts to BTUConvert watts to BTU per hour.
- Therms to kWhConvert US therms to kilowatt-hours.
- BTU CalculatorFind the right air conditioner size for a room.
- AC Size CalculatorEstimate the central air conditioner size for a whole home.
- HVAC Tonnage CalculatorWork out HVAC tonnage either from floor area (using square feet per ton for your climate) or by converting a known cooling load from BTU per hour to tons.
- Thermostat Energy Savings CalculatorSetting your thermostat back while you sleep or are away is one of the simplest ways to cut energy bills.
- Electricity Cost CalculatorFind out how much any appliance or device costs to run.
- Space Heater Cost CalculatorSee exactly what your electric space heater costs to run.
- Water Heater Size CalculatorSize a water heater by your busiest hour of hot water use.
- Pool Heater CalculatorEstimate how many BTUs it takes to warm your pool and how long your heater will need.
- Thermostat Setting GuideRecommended thermostat settings for comfort and lower energy bills, in winter and summer, while you are home, asleep or away.
- Ideal Room Temperature GuideWhat temperature should each room be? Recommended ranges for sleeping, babies, living areas, offices and older adults.
- Aquarium Temperature ChartKeep your fish healthy at the right water temperature.
- Reptile Tank Temperature ChartReptiles need a temperature gradient to regulate their body heat.
- Pet Temperature ChartPets run warmer than people.
- Washing Machine Temperature ChartLaundry labels give wash temperatures in °C.
- Ironing Temperature ChartSet your iron to the right temperature for each fabric to remove wrinkles without scorching or melting.
- Candle Wax Melting Temperature ChartMelting points and typical heating and pouring temperatures for common candle waxes.
- Compost Temperature GuideA healthy hot compost pile heats itself.
Popular conversions
- 5000 BTU/h to kW
- 6000 BTU/h to kW
- 8000 BTU/h to kW
- 10000 BTU/h to kW
- 12000 BTU/h to kW
- 18000 BTU/h to kW
- 24000 BTU/h to kW
- 36000 BTU/h to kW
- 60000 BTU/h to kW
- 100000 BTU/h to kW
- 6000 BTU/h to Tons
- 12000 BTU/h to Tons
- 18000 BTU/h to Tons
- 24000 BTU/h to Tons
- 30000 BTU/h to Tons
- 36000 BTU/h to Tons
- 42000 BTU/h to Tons
- 48000 BTU/h to Tons
- 60000 BTU/h to Tons
- 100 Watts to BTU/h
- 500 Watts to BTU/h
- 750 Watts to BTU/h
- 1000 Watts to BTU/h
- 1500 Watts to BTU/h
Other categories
- Temperature converters
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- Length & height converters
- Weight converters
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- Home improvement calculators
- Tech & auto temperature guides
- Size converters
- Everyday calculators