Ductless Mini-Split vs Central AC: Cost Compared Free

What does $1,875.17 mean?

It means that over 15 years, cooling a 2,000 sq ft home with a ductless mini-split costs $1,875.17 less than cooling it with central AC — $17,486.36 against $19,361.54, install, energy and maintenance all counted. The mini-split costs $1,000 more to install, but it saves $191.68 a year after maintenance, so it catches up in year 6 and keeps saving after that. The load is 40,000 BTU, which is 3.33 tons, and the mini-split uses 2,181.82 kWh a year against 3,692.31 kWh for central — the efficiency gap, not the install price, is what decides the lifetime winner.

Three things to check before you trust the number

The load is a rule of thumb. 20 BTU per sq ft is a planning figure, not a measurement: insulation, windows, climate, ceiling height and duct losses all shift the real load. A well-insulated home needs less than 20 BTU per sq ft; a sun-baked top floor with old windows needs more. If your load is wrong, every number downstream is wrong by the same share — so treat the load as the input to check first.

SEER2 is a lab figure. The ratings are measured under standard test conditions, and installed efficiency depends on sizing, ductwork and climate. Central AC loses energy in ducts — commonly 20 to 30% of cooled air in attic or crawlspace ductwork — which this calculator does not model, so a central system with leaky ducts will cost more than the number here. A mini-split has no ducts to lose energy in, which is part of why its SEER2 advantage shows up in real bills.

The install gap decides the break-even year. The mini-split saves $191.68 a year after maintenance, so it needs just over five years to recover a $1,000 install gap — year 6. Raise the install gap to $2,000 and the mini-split never wins inside 15 years; drop it to zero and the mini-split wins from year 1. Get two itemised quotes before you decide: the install gap moves the answer more than any other single input.

Worked example

On the defaults: a 2,000 sq ft home, mini-split $10,000 install SEER2 22, central $9,000 install SEER2 13, $0.16/kWh, 1,200 hours a year, 15 years.

1. Find the load: 2,000 × 20 is 40,000 BTU, which is 3.33 tons.
2. Find the mini-split energy: 40,000 × 1,200 / (22 × 1,000) is 2,181.82 kWh a year.
3. Find the central energy: 40,000 × 1,200 / (13 × 1,000) is 3,692.31 kWh a year.
4. Find the running costs: 2,181.82 × $0.16 is $349.09 a year for the mini-split, and 3,692.31 × $0.16 is $590.77 a year for central.
5. Find the energy saving: $590.77 − $349.09 is $241.68 a year.
6. Find the net saving: the mini-split costs $50 a year more to maintain, so $241.68 − $50 is $191.68 a year.
7. Find the break-even year: five years of $191.68 is $958.39, short of the $1,000 install gap; six years is $1,150.07, past it — so year 6.
8. Find the 15-year totals: $10,000 + 15 × $349.09 + 15 × $150 is $17,486.36 for the mini-split, and $9,000 + 15 × $590.77 + 15 × $100 is $19,361.54 for central.
9. Find the winner: $19,361.54 − $17,486.36 is $1,875.17 — the mini-split wins.

Year by year: cumulative cost

Every branch, checked

• 3,000 sq ft home: 3,000 sq ft home: Lifetime saving $3,687.76 (3687.762238 unrounded), net saving $312.52/yr, break-even year 4. 3,000 sq ft home — a bigger home needs a bigger load, 60,000 BTU, and the saving grows with it.
• Mini-split install $12,000: Mini-split install $12,000: Lifetime saving −$124.83 (-124.825175 unrounded), net saving $191.68/yr, break-even never within the lifespan. Mini-split install $12,000 — a $2,000 dearer install flips the lifetime winner to central AC.
• Central install $7,000: Central install $7,000: Lifetime saving −$124.83 (-124.825175 unrounded), net saving $191.68/yr, break-even never within the lifespan. Central install $7,000 — a $2,000 cheaper central install flips the lifetime winner to central AC.
• Mini-split SEER2 25: Mini-split SEER2 25: Lifetime saving $2,503.54 (2503.538462 unrounded), net saving $233.57/yr, break-even year 5. Mini-split SEER2 25 — a more efficient mini-split saves more and breaks even in year 5.
• Central SEER2 10: Central SEER2 10: Lifetime saving $4,533.64 (4533.636364 unrounded), net saving $368.91/yr, break-even year 3. Central SEER2 10 — a less efficient central system costs more to run, so the mini-split wins by more.
• Electricity $0.20/kWh: Electricity $0.20/kWh: Lifetime saving $2,781.47 (2781.468531 unrounded), net saving $252.10/yr, break-even year 4. Electricity $0.20/kWh — dearer electricity makes the efficiency gap worth more every year.
• 1,500 cooling hours/yr: 1,500 cooling hours/yr: Lifetime saving $2,781.47 (2781.468531 unrounded), net saving $252.10/yr, break-even year 4. 1,500 cooling hours/yr — a longer cooling season makes the efficiency gap worth more every year.
• 20-year lifespan: 20-year lifespan: Lifetime saving $2,833.57 (2833.566434 unrounded), net saving $191.68/yr, break-even year 6. 20-year lifespan — five more years of saving widens the lifetime gap.
• No maintenance either side: No maintenance either side: Lifetime saving $2,625.17 (2625.174825 unrounded), net saving $241.68/yr, break-even year 5. No maintenance either side — without the $50/yr maintenance gap the net saving is the full energy saving.
• 1,000 sq ft home: 1,000 sq ft home: Lifetime saving $62.59 (62.587413 unrounded), net saving $70.84/yr, break-even year 15. 1,000 sq ft home — a small home saves less in absolute dollars, and break-even takes until year 15.

The reverses, worked backwards

• Smallest home size for $200/yr of net saving: 2100 — at 2100 the figures are Lifetime saving $2,056.43 (2056.433566 unrounded), net saving $203.76/yr, break-even year 5; at the lower neighbor the figures are Lifetime saving $1,875.17 (1875.174825 unrounded), net saving $191.68/yr, break-even year 6; at the upper neighbor the figures are Lifetime saving $2,237.69 (2237.692308 unrounded), net saving $215.85/yr, break-even year 5 — verdict: STEP.
• Largest mini-split install where the mini-split still wins over its lifetime: 11500 — at 11500 the figures are Lifetime saving $375.17 (375.174825 unrounded), net saving $191.68/yr, break-even year 14; at the lower neighbor the figures are Lifetime saving $875.17 (875.174825 unrounded), net saving $191.68/yr, break-even year 11; at the upper neighbor the figures are Lifetime saving −$124.83 (-124.825175 unrounded), net saving $191.68/yr, break-even never within the lifespan — verdict: STEP.
• Smallest mini-split SEER2 for break-even within 10 years: 18 — at 18 the figures are Lifetime saving $711.54 (711.538462 unrounded), net saving $114.10/yr, break-even year 9; at the lower neighbor the figures are Lifetime saving $335.07 (335.067873 unrounded), net saving $89.00/yr, break-even year 12; at the upper neighbor the figures are Lifetime saving $1,048.38 (1048.380567 unrounded), net saving $136.56/yr, break-even year 8 — verdict: STEP.
• Largest central SEER2 for $100/yr of net saving: 15 — at 15 the figures are Lifetime saving $693.64 (693.636364 unrounded), net saving $112.91/yr, break-even year 9; at the lower neighbor the figures are Lifetime saving $1,242.21 (1242.207792 unrounded), net saving $149.48/yr, break-even year 7; at the upper neighbor the figures are Lifetime saving $213.64 (213.636364 unrounded), net saving $80.91/yr, break-even year 13 — verdict: STEP.
• Smallest cooling hours for $150/yr of net saving: 1000 — at 1000 the figures are Lifetime saving $1,270.98 (1270.979021 unrounded), net saving $151.40/yr, break-even year 7; at the lower neighbor the figures are Lifetime saving $968.88 (968.881119 unrounded), net saving $131.26/yr, break-even year 8; at the upper neighbor the figures are Lifetime saving $1,573.08 (1573.076923 unrounded), net saving $171.54/yr, break-even year 6 — verdict: STEP.
• Smallest lifespan for $1,000 of lifetime saving: 11 — at 11 the figures are Lifetime saving $1,108.46 (1108.461538 unrounded), net saving $191.68/yr, break-even year 6; at the lower neighbor the figures are Lifetime saving $916.78 (916.783217 unrounded), net saving $191.68/yr, break-even year 6; at the upper neighbor the figures are Lifetime saving $1,300.14 (1300.139860 unrounded), net saving $191.68/yr, break-even year 6 — verdict: STEP.

What the defaults assume

The defaults are a 2,000 sq ft home, a $10,000 mini-split at SEER2 22 against a $9,000 central system at SEER2 13, $0.16/kWh, 1,200 cooling hours a year and a 15-year lifespan. They are a starting point, not a quote: your home may be bigger or smaller, hotter or milder, and the right answer for you is the one your numbers describe. No rebates or tax credits are modelled, the mini-split's zoning and comfort benefits are not priced in, and duct losses are not modelled either. Put your numbers in, read the answer, and check the working before you use it.

These notes repeat in every explainer section because this page is built to be read start to finish: the load is a rule of thumb; SEER2 is a lab figure; and the install gap decides the break-even year.

Output · formula · meaning

Who uses this

• A homeowner replacing a dead central system — $1,000 more to install, $191.68 a year back, break-even in year 6, $1,875.17 ahead over 15 years.
• A homeowner without ducts weighing a mini-split against new ductwork — the central install here assumes ducts already exist; adding ducts changes the install gap completely.
• A landlord cooling a rental — the year-by-year table shows exactly when the dearer system starts paying for itself.
• An HVAC shopper comparing quotes — two SEER2 ratings and two install prices, and the lifetime gap follows from them.

Accuracy & limitations

The arithmetic is exact on the numbers you type: 40,000 BTU at 1,200 hours and SEER2 22 is 2,181.82 kWh a year, and $349.09 at $0.16/kWh. What the calculator cannot do is measure your home: 20 BTU per sq ft is a rule of thumb — insulation, windows, climate and duct losses shift the real load — and SEER2 ratings are lab figures, so installed efficiency depends on sizing, ductwork and climate. Central duct losses, commonly 20 to 30% of cooled air, are not modelled, which flatters central AC. The mini-split's zoning and comfort benefits are not priced in, and no rebates or tax credits are modelled. Electricity prices are held flat — if rates rise, the efficient system wins by more; if they fall, by less. Treat the answer as a comparison of two quotes, not a quote itself.

Cite this calculator

On a 2,000 sq ft home, the mini-split costs $349.09 a year to run against $590.77 for central AC — a net saving of $191.68 a year after maintenance — and over 15 years the mini-split wins by $1,875.17: the mini-split catches up in year 6. Smallest home size for $200/yr of net saving: 2100. Largest mini-split install where the mini-split still wins over its lifetime: 11500. Smallest mini-split SEER2 for break-even within 10 years: 18. Largest central SEER2 for $100/yr of net saving: 15. Smallest cooling hours for $150/yr of net saving: 1000. Smallest lifespan for $1,000 of lifetime saving: 11. Source: Bright Side Kit, brightoolbox.com.

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