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Repair or Replace HVAC Calculator

Compare repairing your air conditioner or heat pump with replacing it now — counting the repair, the energy each system uses, the replacement you will need eventually, and what money later is worth today.

Method reviewed October 25, 2026. Version 1.0.0. How it works

Your inputs

Systems rated before 2023 show SEER. Multiply by 0.95 for a ducted split system’s approximate SEER2 (RESNET / AHRI factor).

Years. Shown in the working only; it does not change the result. Your estimate of remaining life (below) is what matters.

Your or your technician’s estimate. The sensitivity table shows how much the answer depends on it.

Replacement quotes to compare

From a written quote, after any rebate taken off at the time of sale.

Used only to credit a new system’s remaining value at the end of the comparison (straight line).

What money later is worth to you today, per year, above inflation. 0 % adds costs up plainly.

Above general inflation. 0 % keeps today’s price.

Above general inflation, applied when the repaired system is replaced later.

Result

Repair now, replace later
$17,657
Replace now
$17,402
Replacing now saves
$255

Replacing now costs about $255 less over 15 years, in today’s dollars.

  • Repairing is the cheaper path whenever the repair costs less than about $1,545, at these inputs.
  • Cost is not the only factor: comfort, noise, humidity control, reliability and refrigerant also matter. Systems that use R-22 are harder to repair: U.S. production and import of R-22 (HCFC-22) ended in 2020 (EPA).
Break-even repair price
$1,545
Current system: energy per year
$753
Replacement: energy per year
$494
Lowest-cost replacement quote
1

Replace now — present cost

Quote 1
$17,402

Repair now, then this replacement — present cost

Quote 1
$17,657

Energy per year after replacement

Quote 1
$494

Sensitivity: repair path minus replace path (positive = replacing costs less)

Repaired system lasts 1 years
$1,419
Repaired system lasts 2 years
$1,034
Repaired system lasts 4 years (your input)
$255
Repaired system lasts 6 years
$-535
Repaired system lasts 8 years
$-1,337
Repaired system lasts 10 years
$-2,149
Electricity 25 % cheaper
$15
Electricity 25 % dearer
$496
No discounting (0 %)
$569
Repair quote 50 % higher
$1,155
Show the working
  1. Energy per year = (tons × 12,000 × full-load hours ÷ SEER2 ÷ 1,000) × electricity price
    current $753; replacement 1 $494
  2. Repair path
    $1,800 now + 4 years of energy and repairs, then buy quote 1 in year 4 (the system would be 18 years old) and run it to year 15, less its remaining value = $17,657 today
  3. Replace path
    $11,500 now + 15 years of energy, less the remaining value at year 15 = $17,402 today
  4. Discounting
    each year-t amount × (1 + 3 %)^−t; energy prices × (1 + 0 %)^(t−1)
  5. Break-even repair price = repair quote − (repair path − replace path)
    $1,800 − $255 = $1,545

Two paths over the same years

Repairing is rarely a choice between “repair” and “never replace”. A repaired system keeps running for a while and is then replaced anyway, so the fair comparison is between two paths over the same period:

  • Repair now: pay for the repair, run the old system and pay for its energy and any further repairs until it fails, then buy the replacement.
  • Replace now: pay for the new system today and run it, paying less for energy if it is more efficient.

Both paths end with a newer system in place. The calculator credits whatever value that system still has at the end, so a replacement bought late in the period is not unfairly counted at full price.

Today’s dollars

A dollar spent in ten years costs you less today than a dollar spent now, because you keep the use of that money in the meantime. The calculator converts every future cost to today’s dollars with the discount rate you choose — the same present-value method used to compare any investment. Set the rate to 0 % to add costs up plainly.

The result is the present cost of each path, the difference, and a break-even repair price: the repair quote at which the two paths cost the same.

Why there is no rule of thumb here

Popular shortcuts — such as multiplying the system’s age by the repair cost and replacing above some threshold — ignore efficiency, energy prices and how long the repaired system will really last. We do not use them. The answer depends most on how many more years the repaired system will run, which nobody knows exactly. That is why the sensitivity table shows the result for different remaining lives and energy prices: if the answer is the same across the range, you can decide with confidence; if it flips, the decision is close and other factors should decide.

Worked example

These are the example values the calculator opens with, and the result the engine calculates for them.

Inputs

Current system
Central air conditioner (cooling only)
Cooling size
3 tons
Current system SEER2
10.5
Full-load cooling hours per year
1,200 h
Electricity price
0.183 $/kWh
Age of the current system
14
Repair quote
1,800 $
Years the repaired system will last
4
Other repairs expected per year on the old system
200 $
Replacement quotes to compare
1 quote
Replacement 1: installed price
11,500 $
Replacement 1: SEER2
16
Years to compare
15
Expected life of a new system
15
Discount rate
3 %
Electricity price change per year
0 %
Replacement price change per year
0 %

Result

Repair now, replace later
$17,657
Replace now
$17,402
Replacing now saves
$255
Break-even repair price
$1,545
Current system: energy per year
$753
Replacement: energy per year
$494

Replacing now costs about $255 less over 15 years, in today’s dollars.

Assumptions

  • Both paths are compared over the same number of years, in today’s dollars: amounts in year t are divided by (1 + discount rate)^t. Up-front costs are paid now; yearly costs at the end of each year.
  • Repair path: the repair now, then the old system’s energy and repairs each year until it fails, then the replacement bought at that time. Replace path: the replacement now.
  • A new system still in service at the end is credited with its remaining value, in a straight line over its expected life.
  • Energy covers cooling (and heat pump heating) electricity from the ratings; maintenance that is the same on both paths is left out.

Limitations

  • The answer depends most on how long the repaired system will last, which nobody knows exactly. Use the sensitivity table rather than a single number.
  • Older systems often perform below their original rating; this uses the rating you enter. No rule of thumb (such as age × repair cost) is used.
  • Financing costs are not included; see the Financing Calculator.

Frequently asked questions

How long will my repaired air conditioner last?

Ask the technician who quoted the repair what condition the rest of the system is in: the compressor, coils, electrical parts and refrigerant circuit. Then use a range rather than one number, and read the sensitivity table to see whether the answer changes across that range.

What discount rate should I use?

Use the return you could reasonably earn on the money elsewhere, or the interest rate you would pay to borrow it, above inflation. A few percent is common for household decisions. 0 % treats money later the same as money now and simply adds up the costs.

Should I replace a system that uses R-22?

Often it is worth a close look. U.S. production and import of R-22 ended in 2020 (EPA), so repairs that need refrigerant depend on recovered or reclaimed supply and can be expensive. Enter the quoted repair price and the calculator will show whether it still pays.

Does this include rebates and financing?

Enter the replacement price after any rebate taken off at the time of sale. Rebates paid later and tax credits are not included. For loan payments and interest, use the HVAC Financing Calculator alongside this one.

What efficiency should I enter for my old system?

The rating on its label or in its AHRI certificate. Older systems are rated in SEER and HSPF; multiply SEER by 0.95 and HSPF by 0.85 for the approximate SEER2 and HSPF2 of a ducted split system. A neglected older system may perform below its rating.

Sources

  1. MINHERS Addendum 71i — SEER2 and HSPF2 Conversions — RESNET (factors developed by AHRI). SEER2/SEER = 0.95 and HSPF2/HSPF = 0.85 for ducted split systems; 1.00 / 0.90 for ductless.
  2. Electric Power Monthly, Table 5.6.A — average price to ultimate customers — U.S. Energy Information Administration. U.S. residential electricity price, 18.31 ¢/kWh in July 2026.
  3. Phaseout of Class II Ozone-Depleting Substances — U.S. Environmental Protection Agency. U.S. phaseout schedule: 2020 — no production or import of HCFC-142b and HCFC-22 (R-22); 2030 — no production or import of any HCFCs.
  4. 2023 Central Air Conditioner Standards — FAQ — U.S. DOE, Office of Energy Efficiency & Renewable Energy. Regional SEER2 / EER2 / HSPF2 minimum efficiencies effective 2023.

Spotted an error? Report a problem with this calculator — see our corrections policy.