What is the difference between BTU for heating vs cooling?

Heating BTU (BTU/hr output) refers to the amount of heat a furnace, boiler, or heat pump must add to a space during winter. Cooling BTU refers to the heat a cooling system must remove during summer. In most Canadian climates, the heating BTU requirement is larger than the cooling BTU requirement due to the severity of winters.

How do I convert BTU to tons of air conditioning?

One ton of air conditioning equals 12,000 BTU/hr. To convert BTU to tons, divide BTU/hr by 12,000. For example, 24,000 BTU/hr equals 2 tons. To convert tons to BTU/hr, multiply tons by 12,000.

Is a BTU calculator accurate enough for equipment selection?

A BTU calculator provides a good estimate for preliminary sizing and budget planning. For final equipment selection, especially for new construction or permit applications, a full room-by-room load calculation is recommended. Use our Heating & Cooling Load Estimator for a detailed, code-informed result.

🔥 Load Calculations

BTU Calculator

Q: How many BTU per square foot do I need?

A general rule of thumb is 20 BTU per square foot for cooling and 30-40 BTU per square foot for heating in a cold Canadian climate. However, the actual BTU requirement depends heavily on insulation quality, ceiling height, climate zone, window area, and sun exposure. This BTU calculator refines the estimate by accounting for all these factors.

Calculate the heating and cooling BTU requirements for any room or building. Accounts for room type, size, climate zone, insulation, sun exposure, and occupancy — with instant equipment size recommendations.

Unit System:

🏠 Step 1 — Select Room Type

📏 Step 2 — Room Dimensions

Length *

Width *

Ceiling Height i

Floor Area: — ft²

Volume: — ft³

— or Enter Area Directly i

ft²

Number of Identical Rooms

rooms

Multiplies total BTU for multiple identical rooms/zones

🌍 Step 3 — Climate Zone

☀Very Milde.g. Victoria BC
-4°C / 25°F

🌦Milde.g. Vancouver, Halifax
-8°C / 18°F

🌧Moderatee.g. Toronto, Ottawa
-18°C / 0°F

❄Colde.g. Montreal, Winnipeg
-27°C / -17°F

❌Very Colde.g. Calgary, Edmonton
-33°C / -27°F

🥶Arctic / Subarctice.g. Yellowknife
-44°C / -47°F

🧦 Step 4 — Insulation & Conditions

Insulation Quality i

Sun Exposure i

Window Coverage i

18%

% of exterior walls that are windows

Regular Occupants i

people

Floor Position i

Building Age i

📊 BTU Requirements

BTU/hr

🔥 Heating Requirement

—

BTU/hr

Enter data and calculate

❄ Cooling Requirement

—

BTU/hr

Enter data and calculate

Equipment Sizing Guide

📊 BTU Breakdown by Load Component

Full Results & Comparison Table

Calculation Factor	Value	Heating BTU/hr	Cooling BTU/hr

Export:

How to Use the BTU Calculator

Select Room Type

Click the room type that best matches your space. Kitchens and server rooms have high internal heat gains that reduce cooling needs but are irrelevant to heating. Bedrooms and basements have minimal internal gains. This step automatically applies the correct internal heat gain factor.

Enter Dimensions or Area

Enter the room length and width — floor area and volume calculate automatically. If you know the area already, enter it directly in the "Enter Area Directly" field. Ceiling height matters: a 12-foot vaulted ceiling requires more BTU than a standard 8-foot ceiling for the same floor area. Use the unit converter if your measurements are in different units.

Select Your Climate Zone

Choose the climate zone that matches your location. This is the single largest factor in determining heating BTU requirements. A very cold Edmonton home needs roughly 2.5× more heating BTU than a mild Vancouver home of the same size. For precise outdoor design temperatures, use our design temperature lookup.

Set Insulation & Conditions

Insulation quality has a major impact — an excellently insulated home may require only 40% of the BTU of a poorly insulated one. Sun exposure affects cooling loads significantly: a south-facing room with large windows may need 30–50% more cooling BTU. Window coverage and floor position add further refinement.

Review Results & Next Steps

Results show heating and cooling BTU requirements with visual gauges, equipment size recommendations, and a full breakdown by component. For more precise sizing, proceed to the load estimator or the full heat load calculator. Size your equipment with the furnace sizing, heat pump sizing, or AC sizing calculator.

BTU Calculations for HVAC Sizing — Complete Guide

BTU stands for British Thermal Unit — the amount of energy needed to raise one pound of water by one degree Fahrenheit. In HVAC, BTU/hr (BTU per hour) is used to describe the heating or cooling power of equipment. When we say a furnace is "80,000 BTU," we mean it can deliver 80,000 BTU of heat per hour at its rated output.

BTU per Square Foot — Why Rules of Thumb Fall Short

The most common question in HVAC sizing is "how many BTU per square foot do I need?" The oft-quoted 20 BTU/ft² for cooling is a starting point that ignores climate, insulation, ceiling height, and a dozen other factors. In practice:

A well-insulated modern home in Vancouver needs roughly 15–20 BTU/hr·ft² for heating
The same home in Edmonton needs 35–45 BTU/hr·ft² — more than double
A poorly insulated 1970s home in Toronto might need 50–70 BTU/hr·ft²
A net-zero home anywhere in Canada might achieve 8–12 BTU/hr·ft²

This is why our BTU calculator applies climate zone, insulation quality, building age, and sun exposure corrections to the base area calculation. For even greater accuracy, use the full heat load calculator or the load estimator.

Heating BTU vs. Cooling BTU

Heating and cooling loads are calculated separately because they are driven by different factors. The heating BTU requirement is dominated by envelope heat loss (walls, windows, roof, floor) and infiltration — factors driven by the indoor-outdoor temperature difference. The cooling BTU requirement adds solar heat gain through windows, internal gains from people, lighting, and equipment, and the latent (moisture) load from ventilation and occupancy. In most Canadian climates, the heating BTU requirement is 1.5–3× larger than the cooling requirement. Use the BTU to kWh converter to convert between energy units.

Converting BTU to Tons and kW

Equipment capacity is often expressed in multiple units. One ton of air conditioning or heating equals exactly 12,000 BTU/hr. One kilowatt equals approximately 3,412 BTU/hr. So a 2-ton system is 24,000 BTU/hr or about 7 kW. Our results display all three simultaneously. For precise conversion, use the BTU ↔ kWh converter.

What to Do With Your BTU Result

Size a furnace: Furnace Sizing Calculator (accounts for AFUE efficiency)
Size a heat pump: Heat Pump Sizing Calculator
Size a mini-split: Mini-Split Sizing Calculator
Size an air conditioner: AC Sizing Calculator
Design duct system: CFM Calculator + Duct Sizing Calculator
Evaluate energy costs: Payback Period Calculator

Frequently Asked Questions

This depends heavily on your climate zone and insulation level. As a rough guide for Canada: Vancouver area (mild climate, good insulation): 20–30 BTU/hr·ft². Toronto/Montreal (moderate-cold, average insulation): 35–50 BTU/hr·ft². Calgary/Edmonton (very cold, average insulation): 45–65 BTU/hr·ft². New high-performance homes: 10–20 BTU/hr·ft² anywhere. These are guidelines only — always use a proper heat load calculation for equipment sizing.

Approximate ranges for a moderately insulated home in a cold Canadian climate (e.g. Toronto): 1,000 ft² home: 35,000–50,000 BTU/hr heating, 18,000–24,000 BTU/hr cooling. 1,500 ft² home: 50,000–75,000 BTU/hr heating, 24,000–36,000 BTU/hr cooling. 2,000 ft² home: 65,000–100,000 BTU/hr heating, 36,000–48,000 BTU/hr cooling. Use the calculator above with your specific climate zone and insulation quality for a more accurate estimate, or use the full heat load calculator for maximum accuracy.

One ton of refrigeration (or air conditioning) equals exactly 12,000 BTU/hr. This unit comes from the cooling effect of melting one ton of ice over 24 hours. A 2-ton AC system delivers 24,000 BTU/hr of cooling capacity. Residential systems typically range from 1 to 5 tons (12,000 to 60,000 BTU/hr). Use the BTU converter to convert between BTU/hr, tons, and kW.

In most Canadian climates, size the heating system to the heating load and the cooling system to the cooling load — they are often different pieces of equipment (furnace + AC) or a heat pump that handles both. If using a single heat pump for both heating and cooling, size to the larger of the two loads (usually heating in Canada) and verify the unit performs adequately for the smaller load. The heat pump sizing calculator handles this analysis automatically.

This BTU calculator is an excellent estimating tool for preliminary sizing, system selection, and budgeting — but it is not a substitute for a full room-by-room load calculation for permit applications. Many Canadian jurisdictions now require a formal load calculation report when pulling a mechanical permit for new equipment installation. Use our load estimator for a detailed report, or the detailed heat load calculator for component-by-component analysis.