Is this as accurate as a Manual J?

No. It’s a rule-of-thumb estimate. Use a Manual J for sizing before purchasing equipment.

What if my ceilings are high?

Higher volume means more load. Consider increasing area or selecting a slightly higher capacity.

Can I use this for mini-splits?

Yes as a ballpark, but zone-by-zone loads vary. Use room-level data for multi-zone systems.

Does it include heating and cooling?

It’s a general load estimate; specific heating/cooling loads can differ by climate and building details.

How do I improve accuracy?

Better: do a Manual J, include infiltration, window sizes/orientation, shading, and exact R-values.

energy calculator

Heat Pump Sizing Calculator

Estimate heat pump capacity (BTU and tons) based on home size, climate, and insulation quality.

Results

Estimated capacity (BTU/hr): 32,400
Tonnage (tons): 2.70

How to use this calculator

Enter your home’s square footage.
Choose the climate and insulation/air sealing quality.
Review estimated BTU/hr and tons for a starting point before a Manual J or pro evaluation.

Inputs explained

Climate: Hot/moderate/cold bands adjust BTU per sq ft.
Insulation: Better insulation/air sealing reduces required capacity.

How it works

We start from typical BTU per sq ft by climate (higher in cold climates, lower in hot/moderate).

We apply an insulation factor (poor vs average vs good) and multiply by square footage, then convert to tons (12,000 BTU/ton).

Formula

BTU/hr ≈ Sq ft × Climate BTU/sq ft × Insulation factor
Tons = BTU/hr ÷ 12,000

When to use it

Early-stage budgeting for a heat pump replacement.
Checking if an equipment quote is in the right ballpark.
Comparing size needs for different insulation/air sealing scenarios.

Tips & cautions

For accuracy, get a Manual J load calc. This tool is a simplified starting point.
If ceilings are high or there are many windows/leaks, size may need to be higher.
Right-sizing avoids short cycling and comfort issues; don’t oversize by default.
Simplified rule-of-thumb sizing; not a Manual J.
Does not account for window area, orientation, ACH, or solar gain.
Assumes typical ceiling heights; high ceilings may require more capacity.

Worked examples

1,800 sq ft, moderate, average insulation

BTU ≈ 1,800 × 18 × 1.0 = 32,400
Tons ≈ 2.7

2,200 sq ft, cold, poor insulation

BTU ≈ 2,200 × 22 × 1.1 ≈ 53,240
Tons ≈ 4.4

Deep dive

Estimate heat pump size by entering home square footage, climate, and insulation to get BTU/hr and tons.

Use this as a starting point before a full Manual J load calculation or contractor visit.

FAQs

Is this as accurate as a Manual J?: No. It’s a rule-of-thumb estimate. Use a Manual J for sizing before purchasing equipment.
What if my ceilings are high?: Higher volume means more load. Consider increasing area or selecting a slightly higher capacity.
Can I use this for mini-splits?: Yes as a ballpark, but zone-by-zone loads vary. Use room-level data for multi-zone systems.
Does it include heating and cooling?: It’s a general load estimate; specific heating/cooling loads can differ by climate and building details.
How do I improve accuracy?: Better: do a Manual J, include infiltration, window sizes/orientation, shading, and exact R-values.

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HVAC BTU Calculator

Estimate cooling BTU and tonnage based on room size, ceiling height, insulation, sun exposure, and occupancy.

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Insulation R-Value Calculator

Estimate insulation thickness needed to hit a target R-value.

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Attic Ventilation Calculator

Estimate required net free vent area (NFVA) using 1:150 or 1:300 rules, split between intake and exhaust.

Rule-of-thumb estimate only. Not a substitute for a Manual J or professional HVAC design. Verify with a licensed contractor before purchasing equipment.