How many BTU for 800 sq ft?
Updated October 24, 2026
To heat 800 sq ft (74 m²) you need between 12,000 and 35,100 BTU/h depending on your city and insulation. Here is the calculation city by city, using the CSA F280 method.
Assumption: a 800 sq ft bungalow with no heated basement, 8 ft ceilings, windows in proportion to floor area.
Heating load by city and house age
| City | After 2010 | 1990 to 2010 | 1970 to 1990 | Before 1970 | Cooling* |
|---|---|---|---|---|---|
| Vancouver (-7 °C) | 12,000 | 12,000 | 14,500 | 18,800 | 9,100 |
| Toronto (-18 °C) | 12,300 | 13,600 | 20,000 | 26,000 | 10,200 |
| Halifax (-16 °C) | 12,000 | 12,900 | 19,000 | 24,700 | 8,800 |
| Montreal (-23 °C) | 13,800 | 15,300 | 22,500 | 29,200 | 9,700 |
| Quebec City (-26 °C) | 14,700 | 16,300 | 24,000 | 31,200 | 9,100 |
| Winnipeg (-31 °C) | 16,200 | 18,000 | 26,500 | 34,400 | 9,700 |
| Edmonton (-32 °C) | 16,500 | 18,400 | 27,000 | 35,100 | 8,800 |
* Cooling for a 1990–2010 house, at the city’s summer design temperature.
Which Kanartic system for 800 sq ft?
Newer house in Toronto
ZERO 12,000 wall unitfrom $2,349 · DIY
Covers 98% of the heating load at -18 °C
See on kanartic.ca1990–2010 house in Montreal
ZERO 18,000 wall unitfrom $2,895 · DIY
Covers 100% of the heating load at -23 °C
See on kanartic.caPre-1970 house in Edmonton
Z-PRO 36,000 · 2 zonesfrom $5,325 · DIY
Covers 100% of the heating load at -32 °C
See on kanartic.caWhat about 25 BTU per square foot?
The rule of thumb would give 20,000 BTU/h for 800 sq ft. The component calculation gives 12,000 to 35,100 BTU/h: depending on the house and climate, the rule is off by −43% to +67%.
Frequently asked questions
Is a 12,000 BTU heat pump enough for 800 sq ft?
In Montreal, for a 1990–2010 house, a 12,000 BTU unit covers 78% of the load at -23 °C; for a pre-1970 house, 41%. So you need a bigger unit or backup heat.
How many BTU to cool 800 sq ft?
Between 8,800 and 10,200 BTU/h for a 1990–2010 house, depending on the city. In Canada, heating sets heat pump size, not cooling.
Wall unit or multi-zone for 800 sq ft?
A wall unit is enough for an open area; if bedrooms are closed off, a 2-zone multi-zone heats each room better.
Other floor areas
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How many BTU for my house?Why not to oversizeHeat pump costBy room