Guides

Each guide explains one decision and has the calculator for it built in.

• Heat pump vs gas furnace: which costs less to heatWhether a heat pump or a gas furnace is cheaper to run comes down to one comparison: the price of electricity against the price of gas. Enter your numbers below, then read how the comparison works.
• How much does it cost to run a mini splitThe cost comes from the power the unit draws and how long it runs. Enter the size and rating of your mini split below to see the cost per hour, per day and per month.
• What size air conditioner do I needFor a window or wall air conditioner, the size comes from the area of the room and a few adjustments. Enter the room below, then read how each step works and where the method stops.
• How much electricity does a central AC useThere is no single number: it depends on the size of the system, its rating and the hours it runs. Enter yours below, then see how each one changes the bill.
• Window AC vs central AC costA window unit is cheap to buy and cools one room. A central system costs more and cools the whole house. Enter both below to see the running cost and the payback.
• Tankless vs tank water heater costThe label efficiency is only part of it. What you pay in a year depends on how much hot water you use and what gas and electricity cost where you live. Compare two heaters below.
• How much does a space heater cost to runThe cost is the watts, times the hours it runs, times your price per kWh. Enter your heater below, then read how to lower it.
• Electric car vs gas car cost per mileCost per mile is the easiest way to compare them. Enter your car and your gasoline price below, then see how much the price of electricity in each state changes the answer.