Free HVAC Cost Calculator (+ Guide)

What is a HVAC cost calculator?

An HVAC cost calculator adds up every cost of a new heating and cooling system, from the contractor's quote to the thermostat and permits.

It shows the total with a contingency, the cost per square foot of home and what's left of your budget.

How it works

The cheapest of your quotes goes in the total, next to the costs it doesn't cover.

How to size a new system

The US Department of Energy's consumer guide is blunt about size.

• An oversized cooling system costs too much, gives poor comfort and can lead to mold and poor indoor air
• The rule of thumb of 1 ton of cooling per 400 to 500 sq ft ignores your climate and how efficient the house is
• Your contractor should use the Air Conditioning Contractors of America's Manual J to work out the right size
• A system more than 15 years old is worth replacing for the savings, and regular maintenance can cut heating and cooling costs by 10% or more

Ask every contractor for their Manual J numbers, so the quotes compare the same system.

Refrigerant and tax credits

The EPA requires technicians who service, repair or dispose of equipment that could release refrigerants to be certified under Section 608. Ask for it.

The IRS energy efficient home improvement credit, worth up to $2,000 a year for a qualified heat pump, covered improvements made through December 31, 2025. Work done since then doesn't qualify for it.

How to compare contractors' quotes

The Federal Trade Commission gives this advice before you hire anyone.

• Hire only licensed and insured contractors, and check the license with your state or county
• Get several written estimates, each with the work, the materials, the completion date and the price
• Don't automatically pick the lowest bid, and ask why if the estimates differ a lot
• Get a written contract with the contractor's license number and the start and finish dates
• Never pay the full amount up front, and make the final payment only when the work is done

It also warns that a contractor who asks you to get the permits, or who only takes cash, may be running a scam.

How much contingency to add

A contingency is money set aside for what you find once the walls or the ground are open.

HUD requires one on its 203(k) renovation loans: 10% to 20% of the repair costs on a home 30 years or older, and at least 15% when the utilities don't work.

On a newer home, it's up to the lender, to a maximum of 20%.

A worked example

Here's the example the calculator loads: an 1,800 sq ft home with three quotes of $11,500, $13,200 and $9,800, plus ductwork repairs, a thermostat and the permit.

The cheapest of the three quotes is $9,800, $3,400 less than the dearest. Your other costs add $2,050, so the heating and cooling comes to $11,850 before the contingency.

A 10% contingency adds $1,185, for a total of $13,035. That's $7.24 per square foot of home, and $1,965 left of a $15,000 budget.

Mistakes to avoid

These are the slips that come up most.

• Comparing quotes that size the system differently, without a Manual J calculation
• Replacing the system with the same size by habit, when the house has changed
• Counting on the federal heat pump credit for work done after 2025

Who is the HVAC cost calculator for?

It's for anyone replacing a furnace, an air conditioner or both, and these tools help around it.

• Electricity cost calculator – for running costs
• Square footage calculator – for the home's size
• Home equity loan calculator – if you borrow for it

Size the system before you compare prices, and the cheapest quote is also the right one.