AC Size & Tonnage Calculator
Find Your Correct Air Conditioner Tonnage

Find the correct AC tonnage for your Canadian home. Proper sizing means better comfort,
lower bills, and a system that actually lasts.
📐 Accurate Sizing
🇨🇦 Canadian Climates
⚡ Instant Result
📐
A/C Size Calculator
This short quiz is designed to help homeowners estimate the correct central air conditioning system size and BTU rating for your home.
Select your home type
Approximate home square footage of finished living space
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📐 Size Calculated
Your Recommended AC Size
Recommended Tonnage
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BTU Output
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A certified HVAC contractor performs a Manual J load calculation for exact sizing.

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What Size Air Conditioner Do I Need in Canada?

Choosing the correct AC size is critical. An oversized AC cools quickly but shuts off before removing humidity, leaving your home feeling damp and clammy. It also short-cycles — turning on and off constantly — which wastes energy and wears out the compressor prematurely. never reaches your set temperature — often mistaken for one of several common air conditioner problems. The right size comes from a proper heat load calculation based on your home's square footage, insulation, and local climate.
Home Size (sq ft)Recommended TonnageBTU/h Equivalent
600 – 9001 – 1.5 tonnes12,000 – 18,000 BTU/h
900 – 1,2001.5 – 2 tonnes18,000 – 24,000 BTU/h
1,200 – 1,7002 – 2.5 tonnes24,000 – 30,000 BTU/h
1,700 – 2,2002.5 – 3 tonnes30,000 – 36,000 BTU/h
2,200 – 2,8003 – 3.5 tonnes36,000 – 42,000 BTU/h
2,800 – 3,5003.5 – 4 tonnes42,000 – 48,000 BTU/h
*General estimates only. Use our calculator for a climate-adjusted result based on your specific home and location.

Factors That Affect AC Tonnage Requirements

📏 Square Footage
The primary sizing factor. Measure all cooled living space. Uncooled basements or garages should generally not be included.
🌡️ Local Climate
A home in Windsor, ON (summer design temp 32°C) needs more cooling capacity than the same home in Calgary, AB (27°C design temp).
🏗️ Insulation Quality
Well-insulated homes (R-20+ walls, R-50 attic) require 20–25% less cooling capacity than poorly insulated older homes.
🪟 Windows & Orientation
South- and west-facing windows in summer add significant cooling load. Large unshaded windows can increase required tonnage by 0.5 tonnes or more.
📐 Ceiling Height
9-foot or higher ceilings increase total cooled volume. Homes with vaulted ceilings need more capacity than standard 8-foot ceiling homes.
👥 Occupancy & Appliances
More occupants, open-concept kitchens, and heat-generating appliances all add to your cooling load and may push you to the next tonnage tier. Choosing a high-efficiency system helps offset this added load.

Not sure if repair or replacement makes more sense first? Compare options in our repair or replace guide.

AC Sizing by Canadian Climate Zone

Canada spans ASHRAE climate zones 4 through 8. For cooling purposes, the relevant metric is summer design temperature the temperature your AC must handle on the hottest days. Our calculator uses official summer design temperatures by city to give you an accurate tonnage recommendation.
CitySummer Design TempSizing Impact
Windsor, ON32°C+10% vs baseline
Toronto, ON31°C+8% vs baseline
Ottawa, ON31°C+8% vs baseline
Vancouver, BC28°CBaseline
Calgary, AB27°CBaseline
Winnipeg, MB30°C+5% vs baseline

If your current unit is aging, review these signs your AC needs replacing before sizing a new one.

Curious what proper sizing costs? See our breakdown of central air conditioner cost in Canada.

What People Ask About AC Size & Tonnage Calculator

Is bigger always better when sizing an AC?

No oversizing causes short-cycling and poor humidity removal, so matching AC size to your actual heat load is always correct.

One ton equals 12,000 BTU/h of cooling capacity, and most Canadian homes need 2–3.5 tons depending on size and climate.

Usually yes, since most Canadian central ACs are split systems sharing the furnace's air handler, but a contractor should confirm airflow capacity.

Rebates Available
Canadian homeowners may qualify for up to
$5,000
in federal and provincial rebates on qualifying systems.
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