HVAC calculators & guides
Free hvac tools and plain-English guides for Canada — each gives the answer fast and shows the working behind it.
BTU calculator
How many BTUs do I need? Enter your floor area, ceiling height and climate — get the air conditioner or heater size in BTU/hr, kW and tons, using the standard sizing rules of thumb.
Open tool →Insulation calculator
How much insulation do I need? Enter the wall or attic size and your package coverage — get the area to buy and the number of rolls, batt packs or bags, with a waste allowance worked in.
Open tool →R-value calculator
What is the R-value of your wall, roof or floor? Add each material layer and its thickness — get the total R-value, RSI and U-value, for insulation, walls and attics.
Open tool →Duct size calculator
What size duct do I need? Enter the airflow (CFM or L/s), pick the duct type, and get the minimum round duct diameter and rectangular equivalents instantly.
Open tool →Heat loss calculator
How much heat does your house lose? Enter the floor area, insulation level and temperature difference — get the total heat loss in BTU/hr and kW, plus a suggested furnace or heat pump size.
Open tool →About hvac calculations
Heating and cooling calculations answer one core question in different costumes: how much thermal energy does this space gain or lose, and what equipment moves that much heat? Room dimensions, insulation, climate and occupancy feed the load; the load drives equipment sizing; and oversized equipment is just as real a problem as undersized — it cycles on and off without ever dehumidifying or running efficiently.
The HVAC tools here cover the recurring arithmetic: thermal loads, airflow, and capacity conversions between the units the industry mixes freely. Each shows its inputs and working so you can see exactly which assumptions drove the number.
Using the results
A quick calculation is a planning tool, not a substitute for a full load calculation on a real building. Use these results to budget, compare quotes, and ask sharper questions — and treat a contractor's properly measured load calculation as the final word for equipment you'll live with for fifteen years.