Heating Calculator
Calculate boiler and radiator heating power for private house and apartment: kW and section count by area and heat losses.
Heated area of the house or apartment in m²
Ceiling height in meters (standard — 2.7 m)
Thermal performance of walls, windows, and roof
Specific power depends on the construction region
Calculation formula
P = S × q_region × (h ÷ 2.7) × k_insulation
Floor area is multiplied by region-specific power (80/100/130 W/m²), corrected for ceiling height and insulation quality (poor 1.3; standard 1; good 0.85). Section count equals room power divided by 170 W.
About the heating calculator
The heating calculator quickly estimates boiler power and radiator section count by floor area of a house or apartment. Enter the area, ceiling height, insulation level, and climate zone — the calculator returns total heating capacity in kW and the number of aluminum or bimetal radiator sections.
The calculation is based on a specific power of 80–130 W/m² depending on the region: 80 W per square meter is enough in the south, 100 W in central regions, and 130 W in cold northern climates. Correction factors account for ceiling height relative to the 2.7 m standard and for the quality of wall, window, and roof insulation.
All calculations run locally in your browser — no data is sent to the server and no sign-up is required. Use the calculator free of charge to size a gas or electric boiler, plan a heating system, and distribute capacity across rooms.
Calculator benefits
Climate-aware
Specific power 80/100/130 W/m² across three climate zones — from southern to northern regions.
Insulation correction
Coefficients for poor, standard, and good insulation reflect real heat losses of the building.
Boiler and radiators at once
Single calculation returns boiler power in kW and radiator section count for a typical room.
Frequently asked questions
Is the rule of 1 kW per 10 m² accurate?
It is a simplified rule for central regions with standard insulation and 2.7 m ceilings. In southern climates 0.8 kW per 10 m² is enough; in northern ones you need 1.3 kW. The calculator accounts for region and insulation, so it is more accurate than the flat 1 kW per 10 m² rule.
What are heat losses?
Heat losses are the amount of heat the building loses through walls, windows, roof, and floor in cold weather, measured in watts. Boiler power must fully compensate for heat losses at the lowest design temperature, otherwise the house will not warm up.
Do I need a 20% reserve?
A 15–20% reserve is recommended for gas boilers with domestic hot water and for regions with extremely cold winters. For electric boilers and single-circuit systems the calculated power is enough — running at the limit is undesirable, but overpaying for extra kilowatts is not a good option either.
Bimetal or aluminum radiators?
Aluminum radiators are cheaper and more efficient for a private house with autonomous heating and stable pressure. Bimetal radiators are more expensive but tolerate high pressure and water hammer — they are the typical choice for apartments with central heating.