20 free tools for repairs, replacements and running costs. Each shows its math and sources. None asks for an email.
20 toolsfree, no email, math shownEvery number comes from a named source such as EIA, ENERGY STAR or DOE, or from our own math on one, labeled as ours. HyreHVAC holds no data on quotes or finished jobs.
The short answer
These 20 free HVAC calculators help you decide what to do next. If something failed, start with repair or replace. If you are choosing a system, start with heat pump vs furnace.
If you have bids, use quote comparison. Each tool shows its formula and sources, runs in your browser, and never asks for an email.
Tools for when something is wrong
Start here if the system has failed, is acting up, or is getting old.
The same promises apply to every tool, so they are listed once here.
The formula is on the page
Every calculator shows the math it runs and the source of each constant. Disagree with an input? Change it and see a new answer.
Nothing is emailed or stored
The calculators run in your browser. There is no email wall and no form in front of a result.
They can tell you to do nothing
We do not sell or install equipment, so a tool can conclude that a repair is right, your system is fine, or a heat pump would raise your bill. Several do.
They do not replace a load calculation
The sizing tools run rules of thumb or bill-based estimates and say so. ACCA Manual J sizes equipment; nothing here replaces it.
Ranges stay ranges
Where the evidence is a range, the result is a range. One confident number would look neater and be less true.
Gas and carbon monoxide come first
If you smell gas or a CO alarm sounds, leave the house and call your gas utility or 911 from outside. No tool here replaces that.
Where do the numbers come from?
Every constant comes from a named, dated source you can check.
Fuel prices: EIA’s 2024 state residential electricity and natural gas prices.
Equipment performance: the ENERGY STAR certified product database, 12,562 distinct outdoor units.
Installation faults: the US Department of Energy’s review of 44 residential field studies.
Housing stock: the EIA Residential Energy Consumption Survey (RECS).
Each is worked through in our HVAC research, and every tool links to the study behind its assumptions. If a figure looks wrong, the method is published so you can check it.
Which HVAC calculator do you need?
Pick the tool by the question you have. The last column says what each tool will not do, so you know its limits.
Under 10 CFR 430.32(c)(5) and (c)(6), the floor is SEER2 13.4 for a split AC, and SEER2 14.3 and HSPF2 7.5 for a split heat pump. The same machine scores lower under SEER2, so never compare SEER with SEER2.
January 1, 2023, Southeast and Southwest
The regional rule applies at installation
DOE enforces it by date of manufacture in the North and by date of installation in the Southeast and Southwest. There, an outdoor unit with any certified pairing below the minimum cannot be installed, whatever your quote says.
January 1, 2025
New equipment moved off R-410A; the install deadline did not hold
New home systems need a refrigerant below GWP 700: R-410A (2,088) is out; R-454B and R-32 are in. EPA sets no current install date for systems built from pre-2025 parts. Existing R-410A systems are unaffected (checked September 5, 2026).
December 31, 2025
The federal efficiency tax credit ended
§25C is not available for property placed in service after December 31, 2025 (Public Law 119-21). A quote showing a net price after a federal credit shows a price you cannot get. Utility and state rebates are separate, and many still exist.
The eCFR and Federal Register websites refused automated requests on September 5, 2026, so we read the regulation through the eCFR content API. The AHRI directory returned 403 that day.
Why do HVAC calculators need your location?
Not to route leads; nothing you enter is sent anywhere. Because on the biggest questions, the national answer is wrong for most of the country.
The seasonal COP a heat pump needs to beat a gas furnace on running cost, 2024. The three lowest states, the national average and the three highest.HyreHVAC calculation from EIA 2024 state residential electricity and natural gas prices. Read the electric vs gas price study.
HyreHVAC calculation: a heat pump beats a gas furnace on running cost only above a seasonal COP set by your electricity-to-gas price ratio. On EIA 2024 prices, that is 3.28 nationally, 1.61 in Florida and 6.11 in Alaska.
That is about 3.8 times from easiest to hardest. The same heat pump saves money in one state and raises the bill in another.
Rules differ too. The efficiency minimum varies by region and, in the Southeast and Southwest, applies on install day. The Southwest adds an EER2 test at 95°F on top of SEER2.
So do homes. Ducts, central AC and heating fuel all vary widely by state, per EIA’s RECS survey, and each changes which options are even on the table.
Running cost only. It ignores installed price, comfort, backup heat and any electrical work a fuel switch needs.
What matters more than the efficiency rating?
How the system is installed. It is the best-evidenced finding in home HVAC, and rarely part of a sales pitch.
73.8% of 12,562 ENERGY STAR certified outdoor units carry the cold-climate designation. A catalog share, every model counted once.HyreHVAC calculation from ENERGY STAR certified product data, September 4, 2026.
DOE’s Building Technologies Office reviewed 44 field-study reports. It found faults in 70-90% of installed systems, rising to 90-100% with ducts included.
Duct leaks showed up in 90-100%, low airflow in more than 50%, undercharge in 29-78% and overcharge in 4-50%.
Installed systems delivered 59-84% of rated SEER. Sealing ducts improved efficiency 16-41% and restored 33% of capacity. A tune-up alone returned approximately 5%.
HyreHVAC analysis: the gap between a minimum unit and the best-rated one is often smaller than the gap between a good install and a typical one. You can buy the highest rating and get less than a median unit installed well.
Install quality is hard to sell: it is not on a spec sheet and has no model number. A rating is a number you can print, so the market drifts toward it.
Anyone handling refrigerant must be certified under Section 608 of the Clean Air Act (40 CFR Part 82, Subpart F). That covers refrigerant handling only, not sizing, ducts or commissioning.
What to do: on any replacement, get three things in writing before comparing prices: the load calculation, the certified pairing (AHRI number), and what will be measured at commissioning (airflow, static pressure, charge).
A caution about labels. Cold Climate requires a COP of at least 1.75 and 70% of the 47°F heating capacity at 5°F. Most of the catalog now clears it, so “cold-climate rated” separates models less than it sounds.
What should you ask before any HVAC job?
None needs technical knowledge. Each can be answered in a sentence by whoever saw the equipment, and an unanswered question tells you something too.
What load calculation is this sized from?
A replacement sized from the old unit’s tonnage assumes the old choice was right. If the system always short-cycled or struggled on hot days, that may be why.
What is the AHRI Reference Number of the proposed pairing?
A certified rating belongs to a specific outdoor unit, indoor coil and air handler. The number is checkable in a public directory.
Does the quote include ducts, electrical and the permit?
A quote for equipment and labor only assumes the ducts and wiring are fine and no permit is needed. One of those is often untrue.
What will you measure at commissioning, and will I get the readings?
Airflow, static pressure and refrigerant charge, on paper. Given the fault rates above, it is the most valuable question here.
A price shown after a federal tax credit
§25C ended for property placed in service after December 31, 2025. Compare gross prices. Utility and state rebates are separate.
Urgency blamed on a refrigerant deadline
The install deadline widely reported for R-410A equipment is not in force as reported. No rule affects your existing system.
We do not rank contractors, hold no job or price data, and take no fee for sending you anywhere.
What can’t these HVAC tools do?
Listed once here instead of on every page. Some are choices; some are limits of public data.
See your equipment. No calculator can diagnose a fault or judge a compressor. Where the decision depends on condition, someone has to look at the machine.
Price anything. HyreHVAC does not install, service or sell HVAC equipment, and holds no data on quotes, invoices or finished jobs. Nothing here is a price we observed. That is also why these tools can tell you to keep the system you have. Tools that involve money take your own quote as the input.
Predict how long equipment lasts. 9.6% of US households with cooling run equipment 20 years old or more (RECS 2020). That snapshot says nothing about systems already removed, so it cannot give a lifespan.
Replace a load calculation, permit or inspection. Local code adoption varies, and nothing here says what applies at your address.
Tell you who to hire. We do not rank contractors or take referral fees. The quote comparison checks whether bids describe the same job, which can be answered, not which firm is better, which cannot.
Questions this calculator answers
Are these HVAC calculators free?
Yes, all of them, with no email address needed. The result shows on screen, and the formula behind it is printed on the page.
Which HVAC calculator should I start with?
Start from your decision. Equipment failed: repair or replace. Choosing a new system: heat pump vs furnace, then sizing. Bids in hand: quote comparison. Something is wrong right now: the emergency check.
Can I size my HVAC system with these tools?
Not to buy equipment. The sizing tools help you judge whether a proposal is in the right range. Equipment should be chosen from an ACCA Manual J load calculation, which counts orientation, windows, insulation, air leaks and ceiling height.
Do these tools sell my details to contractors?
No. The calculators run in your browser and submit nothing. HyreHVAC does not sell or install equipment.
Where do the numbers in these calculators come from?
EIA for fuel prices, the ENERGY STAR certified product database for equipment performance, DOE’s review of 44 field studies for installation faults, and EIA’s RECS survey for housing. Each tool links to its research page.
Is a heat pump cheaper to run than a gas furnace?
It depends on your state. At US average 2024 prices, a heat pump needs a seasonal COP of 3.28 to beat a 95% gas furnace, and that bar varies more than threefold by state. The heat pump vs furnace calculator shows yours.
Sources and methodology
Figures dated EIA 2024 fuel prices; ENERGY STAR certified product data. Last reviewed .
Regional Standards Enforcement (US Department of Energy, Office of the General Counsel, retrieved 2026-09-05. Enforcement by manufacture date in the North and install date in the Southeast and Southwest.)
Technology Transitions: HFC restrictions by sector (US EPA, retrieved 2026-09-04. The GWP 700 limit, the January 1, 2025 manufacture cutoff, and no current install date for home systems built from pre-2025 components.)
Energy Efficient Home Improvement Credit (IRS, retrieved 2026-08-12. §25C is not available for property placed in service after December 31, 2025, following Public Law 119-21.)