Calculate the right heat pump size for your home. Dual-load (cooling + heating) math, balance point estimate, and aux heat capacity. Standard vs cold-climate (CCASHP) equipment comparison across all US climate zones.
Reviewed May 22, 2026
Enter your home characteristics, then click Calculate to see the recommended heat pump size, balance point, and aux heat capacity as a sized chart.
+600 BTU per person above 2
Enter your inputs above, then click Calculate
Result will appear here with the recommended size, capacity-vs-temperature chart, balance point, aux heat sizing, operating cost comparison, and federal incentive eligibility.
Climate zone is the single most important input in any HVAC sizing decision — it drives both heating and cooling design temperatures and the equipment-class recommendation. The reference card below covers all eight US climate zones with sample cities and design temperatures.
The single concept that separates heat pump sizing from AC sizing is that heat pump heating capacity drops with outdoor temperature. The chart below shows the standard residential heat pump curve, the cold-climate (CCASHP) curve, and a typical home heating-load line. The intersection of the capacity curve and the load line is the balance point — the temperature below which aux heat must supplement the heat pump.
The CCASHP curve sits well above the standard curve at low temperatures, which is why the same nominal tonnage produces a much lower balance point with CCASHP equipment. In zones 5-8 that difference reduces aux heat runtime by 60-80% across a heating season — typically translating to $200-$600 per year of avoided electric-resistance operating cost. See the heat pump sizing article for the full balance-point math and the aux heat article for the resistance-strip sizing rules.
Heat pump sizing is harder than AC sizing because the heat pump handles both jobs — cooling in summer and heating in winter — with capacity that varies with outdoor temperature. This calculator computes both peak loads, picks the larger as the equipment size, then estimates the balance point and aux heat capacity required at the heating design temperature.
Enter your home characteristics in the inputs above, click Calculate, and the result chart shows recommended tonnage, balance point, aux heat capacity at design, and equipment class recommendation. For a deeper walkthrough on a specific home size, the Common Scenarios grid below links to dedicated pages for each common house size with 10 worked use cases per page.
Heat pump sizing rests on three concepts that AC sizing does not require. Get these right and the equipment decision follows naturally.
The outdoor temperature at which heat pump capacity equals home heating load. Above the balance point, the heat pump alone keeps up. Below, aux heat supplements.
A 2.5-ton standard heat pump in a 1,500 sqft zone 5 home has a balance point in the high 20s°F. The same home with CCASHP equipment drops the balance point to the low teens°F — reducing aux runtime 60–80 percent across the heating season.
Electric resistance heat strips that fire when the heat pump cannot meet load. Aux heat costs 2–3× per BTU more than heat pump heat at typical electricity rates.
Aux strip kits come in 5kW, 10kW, 15kW, 20kW standard sizes. Right-sizing matters: too small fails on coldest days, too large unnecessarily increases peak electrical draw and may force panel upgrade.
NEEP-listed cold-climate (CCASHP) heat pumps deliver 85 percent of rated capacity at 17°F vs 60 percent for standard equipment. The difference shows up directly in balance point and aux runtime.
CCASHP equipment costs $2,000–$5,000 more than standard at typical residential sizes. Federal IRA 25C tax credit returns up to $2,000; many state and utility rebates favor CCASHP. Premium often pays back in 6–12 years.
AC sizing optimizes for one number: the cooling load at the 1 percent cooling design temperature. Heat pump sizing must handle two: cooling load AND heating load at the 99 percent heating design temperature. These are usually different numbers, and the difference grows with climate extremity.
The calculator picks the larger of the two loads as the equipment size, then computes the balance point — the outdoor temperature where the heat pump's heating capacity equals the home's heating load. Above the balance point, the heat pump alone is enough. Below, aux heat fills the gap.
This dual-load methodology is what separates heat pump sizing from AC sizing and why the AC size calculator gives the wrong answer for heat pumps.
Same home, different climate zones. Heating-to-cooling load ratio drives equipment selection from cooling-dominated (zone 1-3) to heating-dominated (zone 5+).
| Zone | Cities | Heating design | Cooling design | Load ratio | Driver | Equipment |
|---|---|---|---|---|---|---|
| Zone 1 | South Florida, Hawaii | 47°F | 91°F | 0.3× | Cooling | Standard; cooling drives size |
| Zone 2 | Houston, NOLA, Tampa | 30°F | 95°F | 0.5× | Cooling | Standard; aux rarely fires |
| Zone 3 | Atlanta, Memphis, Charlotte | 22°F | 93°F | 0.7× | Cooling | Standard; low aux runtime |
| Zone 4 | DC, Cincinnati, St Louis | 15°F | 90°F | 1.0× | Balanced | Standard or CCASHP both work |
| Zone 5 | Cleveland, Boston, Denver | 5°F | 88°F | 1.3× | Heating | CCASHP recommended |
| Zone 6 | Minneapolis, Buffalo | -2°F | 86°F | 1.6× | Heating | CCASHP strongly recommended |
| Zone 7 | N Minnesota, mountain west | -10°F | 84°F | 1.9× | Heating | CCASHP required + dual-fuel option |
| Zone 8 | Interior Alaska | -20°F | 80°F | 2.2× | Heating | CCASHP + dual-fuel typical |
Design temperatures per ASHRAE Standard 169-2020 (99% heating, 1% cooling).
Worked heat pump sizing across the most common US home sizes. Each page contains 10 use cases spanning climate zones, equipment classes, and architecture choices — plus equipment options, climate variation, common mistakes, and a calculator pre-loaded with that scenario's defaults.
Recommended
2.5 tons
Balance point
23°F
10 worked use cases across climate zones, equipment classes, and home archetypes.
View full page →
Recommended
3 tons
Balance point
23°F
10 worked use cases across climate zones, equipment classes, and home archetypes.
View full page →
Recommended
3.5 tons
Balance point
25°F
10 worked use cases across climate zones, equipment classes, and home archetypes.
View full page →
Recommended
5 tons
Balance point
23°F
10 worked use cases across climate zones, equipment classes, and home archetypes.
View full page →
Recommended
5 tons
Balance point
28°F
10 worked use cases across climate zones, equipment classes, and home archetypes.
View full page →
Recommended
5 tons
Balance point
33°F
10 worked use cases across climate zones, equipment classes, and home archetypes.
View full page →
Three installation architectures cover residential heat pump scenarios. Choice depends on existing ductwork, comfort priority, and budget.
Homes with existing ductwork
Pros
Considerations
No existing ductwork, or room-by-room control
Pros
Considerations
Cheap natural gas markets, transition retrofits
Pros
Considerations
The Inflation Reduction Act materially shifted heat pump economics in the US. Stack federal credit with state and utility programs for total project savings.
Federal IRA 25C tax credit
Up to $2,000
30 percent of project cost up to a $2,000 cap for qualifying heat pumps. ENERGY STAR Most Efficient or CCASHP-listed equipment typically qualifies. Applied as a non-refundable tax credit on federal income tax return.
IRA High-Efficiency Electric Home Rebate (HEEHR)
Up to $8,000
Income-tiered rebate for low and moderate income households. Up to $8,000 for heat pump installations. Administered by states; rollout varies by jurisdiction through 2024-2026.
State and utility rebates
$500–$5,000+
Examples: NYSERDA Clean Heat, Mass Save, Efficiency Vermont, Energize CT, ComEd, Xcel Energy, NW Natural Smart Energy. Stack with federal credit; oil-furnace replacement programs often pay more.
Eligibility and amounts current as of 2024. Check program specifics before committing to equipment; some require Manual J documentation as part of the application.
High-level mistakes that show up across home sizes and climate zones. See the specific Common Scenario page for your home size for size-specific mistakes.
A heat pump must handle both cooling and heating. In zones 4+, heating load is the larger of the two. Sizing to cooling alone leaves heating capacity short, forcing aux heat to fire frequently at 2–3× the operating cost of heat pump heat.
Standard heat pumps work in zone 5 but produce a balance point in the high 20s°F. CCASHP equipment shifts the balance point to the teens°F, reducing aux runtime 60–80 percent. With IRA tax credit and state/utility rebates, CCASHP premium often pays back in 6–12 years.
Oversized heat pumps short-cycle (turn on and off rapidly), control humidity poorly in summer, deliver uneven heating in winter, and wear out faster. The DOE identifies oversizing as a top-three residential HVAC problem.
Heat pumps with aux heat strips can draw 50–100+ amps in heating mode at design conditions. Older 100-amp services may need upgrade ($1,500–$4,000) before installation. 200-amp services are typically fine for most residential sizes.
AC sizing alone gives the wrong answer for heat pump equipment. Use this dual-load calculator, not the BTU or AC sizing calculator, for heat pump decisions. Heat pump sizing must consider both peak cooling and peak heating loads.
Use this calculator
For planning-grade sizing
Upgrade to full Manual J
When precision matters
The calculator implements the dual-load methodology from the heat pump sizing article. Cooling load uses the BTU calculator methodology (baseline 22 BTU/sqft with climate, ceiling, sun, insulation, space-type adjustments). Heating load multiplies cooling load by a climate-zone heating factor calibrated against ASHRAE Standard 169-2020 design temperatures and ACCA Manual J reference cases.
Equipment sizing picks the larger load and rounds to standard residential tonnage (12, 18, 24, 30, 36, 42, 48, 60 kBTU). Balance point finds the outdoor temperature where the heat pump's heating capacity equals the home's heating load, using piecewise capacity curves derived from ENERGY STAR performance data for standard equipment and NEEP CCASHP testing protocols for cold-climate equipment. Aux heat at design is the difference between heating load and heat pump capacity at the heating design temperature.
Accuracy targets ±15 percent on whole-home heating and cooling loads versus ACCA Manual J reference cases for typical residential construction. Verification methodology is documented in the how we verify article. For permit-grade equipment selection on a real install (typically $8,000-$20,000 equipment + install cost), use ACCA-approved software (Wrightsoft Right-J, Cool Calc Manual J, Elite RHVAC) or a certified contractor.
The cornerstone article on heat pump sizing methodology this calculator implements.
How aux heat strips work and how to size them for your equipment.
How and why heat pumps defrost, and how CCASHP equipment manages it.
For permit-grade equipment specification, you need a full Manual J calculation.
Reviewed May 22, 2026