Sunroom Cost Calculator
Estimate a sunroom from its footprint and the $/sq ft you enter for a 3-season or 4-season build.
Calculator
A 200 sq ft sunroom at $250.00/sq ft is about $50,000.00. A 4-season, insulated + conditioned room costs far more per sq ft than a 3-season one — use the figure that matches your build.
A sunroom adds bright, glass-walled square footage to a house. The cost is driven by the footprint and, above all, by which build you choose: a 3-season sunroom (enclosed but not insulated or conditioned) costs far less per square foot than a 4-season room (fully insulated and tied into heating and cooling so it lives like the rest of the house).
This calculator multiplies your footprint by the $/sq ft you enter. Pick the rate that matches the build you want — the reference table below explains the two options.
Formula
A single multiplication on your chosen rate:
total = area (sq ft) × your $/sq ft
The $/sq ft is where the 3-season vs 4-season decision shows up: a 4-season room carries insulation, a conditioned envelope and an HVAC tie-in, so its rate is well above a 3-season enclosure. Enter the figure from a quote for the build you actually want.
Worked example
For a 200 sq ft sunroom at $250/sq ft (a mid 4-season rate you entered):
200 × $250 = $50,000
So the estimate is about $50,000. Drop to a 3-season build at a lower rate and the same footprint costs noticeably less; that single choice moves the number more than the square footage does.
3-season vs 4-season
The build type is the biggest lever on a sunroom budget. A 3-season sunroom is an enclosed, windowed room used spring through fall — no insulation, no heating or cooling — and it is the cheaper per square foot. A 4-season room is fully insulated, weather-sealed and connected to your HVAC so it is usable year-round like any living space, at a materially higher rate. Foundation type, glazing quality and roof style shift the number too — all of which live in the rate you enter, not in a stored price list.
A conditioned 4-season room means electrical and often HVAC and structural work: use licensed pros, pull the permit and confirm code with your building department.
Beyond the build type, the foundation carries real cost: a sunroom on a new footing or slab is a bigger project than one built on an existing deck or patio, and the roof style (a solid insulated roof versus a glass or polycarbonate one) shifts both price and comfort. Glazing quality matters too — better-insulated glass costs more up front but is what makes a 4-season room usable in winter. All of these live inside the single $/sq ft you enter, so choose a quote that reflects the exact build you are pricing rather than a generic figure.
Reference table
Sunrooms span a wide range because the two common builds are very different projects. Use them as guidance for the $/sq ft you enter — the calculator stores no prices.
| Type | What it is | Relative $/sq ft |
|---|---|---|
| 3-season sunroom (no HVAC) | Enclosed room with windows, used spring–fall; not insulated or conditioned. | Lower |
| 4-season room (insulated + HVAC) | Fully insulated and tied into heating/cooling; used year-round like living space. | Higher |
Bands are labeled planning typicals, not current market pricing — enter the figure from your own quote.
Frequently asked questions
How much does a sunroom cost?
Multiply the footprint by the $/sq ft for the build you want: 200 sq ft at $250/sq ft is about $50,000. A 3-season enclosure uses a lower rate than a conditioned 4-season room, so the build type matters more than size.
What is the difference between a 3-season and a 4-season sunroom?
A 3-season sunroom is enclosed but not insulated or conditioned, so it is comfortable spring through fall. A 4-season room is fully insulated and tied into heating and cooling, so it lives like the rest of the house year-round — and costs more per square foot.
Why is a 4-season sunroom more per square foot?
Because it adds insulation, a sealed and conditioned envelope, better glazing and an HVAC connection, plus the electrical and sometimes structural work that goes with them. Enter a 4-season rate from your quote to capture that in the estimate.
Does a sunroom need a permit?
Almost always — it is an addition. A conditioned 4-season room adds electrical and HVAC scope on top. Confirm permits, setbacks and code with your local building department, and use licensed professionals for the structural, electrical and mechanical work.
How do I estimate a 200 sq ft sunroom?
Enter 200 sq ft and the $/sq ft that matches your chosen build; at $250/sq ft that is about $50,000. Get the rate from a written quote for a 3-season or 4-season room so the estimate reflects the project you actually plan.