How many BTU for 1,800 sq ft?
Updated October 24, 2026
To heat 1,800 sq ft (167 m²) you need between 27,000 and 61,700 BTU/h depending on your city and insulation. Here is the calculation city by city, using the CSA F280 method.
Assumption: a 1,800 sq ft two-storey house 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) | 27,000 | 27,000 | 27,000 | 33,200 | 14,500 |
| Toronto (-18 °C) | 27,000 | 27,000 | 34,400 | 45,700 | 16,900 |
| Halifax (-16 °C) | 27,000 | 27,000 | 32,600 | 43,400 | 13,900 |
| Montreal (-23 °C) | 27,000 | 27,000 | 38,700 | 51,500 | 15,700 |
| Quebec City (-26 °C) | 27,000 | 28,500 | 41,200 | 54,900 | 14,500 |
| Winnipeg (-31 °C) | 28,000 | 31,500 | 45,500 | 60,600 | 15,700 |
| Edmonton (-32 °C) | 28,500 | 32,100 | 46,400 | 61,700 | 13,900 |
* Cooling for a 1990–2010 house, at the city’s summer design temperature.
Which Kanartic system for 1,800 sq ft?
Newer house in Toronto
Z-PRO 27,000 · 2 zonesfrom $4,775 · DIY
Covers 100% of the heating load at -18 °C
See on kanartic.ca1990–2010 house in Montreal
Z-PRO 27,000 · 2 zonesfrom $4,775 · DIY
Covers 100% of the heating load at -23 °C
See on kanartic.caPre-1970 house in Edmonton
Z-PRO 36,000 · 2 zones + ZERO 24,000 wall unitfrom $8,724 · DIY
Covers 97% of the heating load at -32 °C
See on kanartic.caWhat about 25 BTU per square foot?
The rule of thumb would give 45,000 BTU/h for 1,800 sq ft. The component calculation gives 27,000 to 61,700 BTU/h: depending on the house and climate, the rule is off by −27% to +67%.
Frequently asked questions
Is a 12,000 BTU heat pump enough for 1,800 sq ft?
In Montreal, for a 1990–2010 house, a 12,000 BTU unit covers 44% of the load at -23 °C; for a pre-1970 house, 23%. So you need a bigger unit or backup heat.
How many BTU to cool 1,800 sq ft?
Between 13,900 and 16,900 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 1,800 sq ft?
At this size, a multi-zone puts one indoor unit per floor or large room, connected to a single outdoor unit.
Other floor areas
1,400 sq ft1,500 sq ft1,600 sq ft2,000 sq ft2,200 sq ft2,400 sq ftAll
How many BTU for my house?Why not to oversizeHeat pump costBy room