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Heat Pump Size Calculator

A heat pump size calculator estimates the tonnage and BTU a heat pump needs to heat and cool your home, from its floor area and climate. It rounds to a standard size so you can compare units.

Your measurements

Result

Heat pumps do double duty — heating and cooling — so accurate sizing matters even more than a furnace: too big and it short-cycles, leaving the air clammy.

How it is calculated

We use about 1 ton per 450 (cold) to 600 (warm) sq ft and round up to a standard size (1 ton = 12,000 BTU). This is a planning estimate — a Manual J load calculation is the proper way to size for short-cycling, humidity and cold-climate performance.

Steps

Enter your home's conditioned floor area.
Pick your climate zone.
Read the tonnage and the equivalent BTU.
Match it to a standard 1.5-5 ton unit.
Have an installer confirm with a Manual J load calculation.

Worked example

An 1,800 sq ft home in a moderate climate works out to about 3.6 tons — rounded to a 4-ton (48,000 BTU) heat pump.

Common questions

What size heat pump do I need?

Roughly 1 ton per 450-600 sq ft depending on climate. An average home is about 2-4 tons; the calculator rounds to a standard size.

What is a ton?

12,000 BTU per hour of capacity. A 3-ton heat pump is 36,000 BTU.

Why not just size big?

An oversized heat pump short-cycles, wastes energy and leaves humidity behind. Right-sizing is more comfortable and efficient.

Does it heat and cool?

Yes — a heat pump moves heat both ways, so this size covers cooling in summer and heating in milder winters; cold climates may add backup heat.