HeatPumpSizer: free heatpumpsizer planning calculators

Calculators

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What this site does

HeatPumpSizer gives homeowners plain-language tools to understand heat pump size, running cost and fit before they talk to installers. The calculators turn floor area, climate and a few house details into rough numbers you can bring to a quote meeting. The guides explain the terms that appear on spec sheets and proposals, such as tons, HSPF2, SEER2, COP and balance point, so you can compare offers on substance rather than brochures. Nothing here replaces a site visit. A licensed HVAC contractor should run a room-by-room load calculation, and electrical and refrigerant work belongs to licensed trades.

How a heat pump works in one minute

Refrigerant circulates between an outdoor unit and an indoor coil or head. In heating mode it absorbs heat from outdoor air, even cold air, and the compressor raises its temperature so it can release that heat indoors. In cooling mode the flow reverses. Because the unit moves heat rather than burning fuel or using resistance elements, it can deliver two to four units of heat for each unit of electricity in mild weather. That ratio, the coefficient of performance, falls as outdoor temperatures drop, which is why cold-climate models and correct sizing matter. Read COP explained for the details.

The three numbers that matter most

First, your design heat loss: how many BTU per hour your home loses on a typical cold day for your area. Second, the unit's capacity at that design temperature, which is often well below its headline rating. Third, its seasonal efficiency, shown as HSPF2 for heating and SEER2 for cooling. Get those three right and most other choices, such as ducted or ductless and brand, become easier.

Start with the calculators

• Heat pump size calculator for a whole-home estimate.
• Mini-split size calculator for a single room or zone.
• Heat pump operating cost calculator to compare with gas.
• BTU to tons calculator to translate spec sheets.

Worked example

Figures below are illustrative examples (2026-10-29), not quotes or guarantees.

Consider a 1,600 sq ft two-storey home in a moderate climate with average insulation. The size calculator gives about 1,600 × 35 = 56,000 BTU/h as an upper planning range, roughly 4.7 tons. A contractor's room-by-room calculation finds 38,000 BTU/h at a 5°F design low after accounting for new windows and attic insulation. The homeowner shortlists 3-ton cold-climate units whose spec tables show at least 38,000 BTU/h available at 5°F. If one model delivers only 28,000 BTU/h at that temperature, the difference would come from backup heat on the coldest nights. Using the operating cost calculator with local rates, the family then compares running costs against their existing furnace before deciding.

Choosing a system type

Ducted heat pumps replace or work with a central furnace and air handler, using existing ducts. Ductless mini-splits mount heads in individual rooms and suit homes without ducts, additions or rooms that are always too hot or cold. Some homes use both. Our ducted vs ductless guide walks through the trade-offs, and heat pump vs furnace compares the main heating choices. For very cold regions, read cold-climate heat pumps; for ground-source systems, see geothermal vs air source.

Costs and incentives

Installed cost depends on system type, capacity, electrical upgrades and ductwork. Our installation cost guide explains what drives quotes. Incentive programs change often and differ by country, province, state and utility, so we do not promise any amounts. Start with heat pump rebates in Canada or heat pump rebates in the US for where to check current rules.

Living with a heat pump

Heat pumps behave differently from furnaces. Supply air feels warm rather than hot, the outdoor unit periodically runs a defrost cycle, and big thermostat setbacks can trigger backup heat. Our thermostat settings guide covers sensible schedules. If something seems wrong, the heat pump not heating checklist covers safe homeowner checks before calling for service, and heat pump lifespan explains maintenance that helps equipment last.

Safety and professional help

Heat pumps involve refrigerant under pressure and high-voltage circuits. Refrigerant handling requires a licensed technician, and new circuits or panel changes require a licensed electrician and usually a permit. Our DIY mini-split guide explains why even "DIY" kits need professional steps. Every number on this site is an estimate for planning, not an ACCA Manual J or CSA F280 calculation and not a quote.

How to use this site with your installer

Print or save your calculator results and bring them to quote visits. Ask each contractor how they calculated the load, what design temperature they used, and what output the proposed unit delivers at that temperature. Ask whether the proposal includes backup heat, electrical work, a new thermostat and permit fees. Comparing answers side by side helps spot quotes that rely on rules of thumb or that oversize to avoid callbacks. Our heat pump FAQ collects other common questions.

Who writes these pages

The site is a planning resource maintained by Charland & Co. Pages are reviewed for clarity and updated as standards such as HSPF2 and SEER2 change. If you spot an error or have a question, write to hello@charlandandco.com. We do not sell equipment and the pages contain no paid placements.

FAQ

Will a heat pump work in a cold climate?

Many current cold-climate models keep heating well below 0°F, though output and efficiency drop. Check performance at your design low.

Do I need to remove my furnace?

No. A dual-fuel setup keeps the furnace as backup. See heat pump vs furnace.

How accurate are the calculators?

They are rough planning estimates. A licensed contractor should do a load calculation.

Do heat pumps cool too?

Yes. The same system provides air conditioning. See heat pump vs air conditioner.