Sizing Guide for a Mini Split System

How big a mini split do you need? In Toronto, a ductless heat pump has to be sized for winter heating, not just summer cooling. Use the chart below as a starting point, then let us confirm it with a heat-loss calculation before you buy.

  • ✓ Sized for heating at Toronto winter temperatures
  • ✓ Mitsubishi, Panasonic, Bosch and AirQuest ductless systems
  • ✓ Free sizing check from your photos and room sizes
  • ✓ 1-year labour warranty on every installation

📏 Mini Split Size by Room

Indoor unit size Typical space Typical use
6,000 BTU Very small rooms Supplemental zone, small office
9,000 BTU Up to about 450 sq ft Bedroom, small room
12,000 BTU About 550–700 sq ft Large bedroom, office, basement room
18,000 BTU About 800–1,000 sq ft Living area, open basement
24,000 BTU About 1,100–1,400 sq ft Large open area
30,000 BTU About 1,400–1,700 sq ft Large open-concept floor
36,000 BTU About 1,700–2,000 sq ft Very large area, light commercial

These are typical ranges for a reasonably insulated Toronto home. Older houses, rooms with lots of glass, top floors and cathedral ceilings often need the next size up; new, well-sealed homes may need less.

🧮 What Changes the Size

  • ✓ Insulation and air sealing: the biggest factor in winter heat loss.
  • ✓ Windows: large or south- and west-facing glass adds summer heat gain and winter heat loss.
  • ✓ Ceiling height: a 12 ft ceiling has about 50% more air than an 8 ft one.
  • ✓ Floor and location: top floors and rooms over garages lose more heat; basements lose less.
  • ✓ Open layout: one head can serve an open area, but closed-off rooms need their own head or airflow.
  • ✓ Heating vs cooling: in Toronto the heating load is usually larger, so we size to heating and check cooling.

❄️ Size for Winter, Not Just Summer

A unit sized only for cooling can run out of heat on a -20°C night. We look at the unit's heating output at low temperatures, not just its nominal BTU rating. That is why we recommend cold-climate heat pumps for any home that will rely on ductless for heat.

💡 Do not oversize. An oversized head short-cycles, controls humidity poorly in summer and costs more. Inverter units modulate, but each one still has a minimum output.

🏠 Single-Zone or Multi-Zone?

Situation Usually best
One room or one open area Single-zone: one outdoor unit, one indoor head
Several rooms on one or two floors Multi-zone: one outdoor unit, two or more heads
Whole home, several floors Multi-zone, two systems, or a ducted heat pump

On multi-zone systems the outdoor unit must match the total of the indoor heads. If the heads add up to more than the outdoor unit can deliver, every head gets proportionally less output when they all run.

🛒 Shop Ductless Systems

🔗 Related Guides & Services

📍 Areas We Serve

Ductless heat pump sizing and installation throughout Toronto and the GTA:

Toronto · North York · Scarborough · Etobicoke · Vaughan · Markham · Richmond Hill · Aurora · Newmarket · East Gwillimbury · King City · Stouffville · Mississauga · Brampton · Oakville · Milton · Burlington · Barrie · Innisfil · Orillia · Bradford · Keswick · Ajax · Pickering · Whitby · Oshawa · Orangeville

📏 Get Your Mini Split Sized

Send us a few photos and the size of the space. We will recommend the right system and give you a clear written price.

📞 Call 416-652-4323

or fill out our form for a free consultation · Serving Toronto & the GTA

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