Sunroom Cost Calculator
Quick answer: Sunroom cost = floor area × price per square foot for the type. Three-season rooms run about $80–$230 per sq ft and four-season rooms about $200–$400 (HomeGuide, 2026). Worked example: a 12 × 12 ft sunroom is 144 sq ft, so a mid-range three-season room costs about $18,648–$25,992 and a mid-range four-season room about $38,304–$48,096.
A sunroom is priced by the square foot, and the type decides the rate: a three-season room (glass or screen panels, no heating or cooling) runs about $80–$230 per sq ft, and a four-season room (insulated, double-glazed, heated and cooled) about $200–$400. Enter the room size and how basic or premium the build is to see the likely range, the full published range and what the same room costs as the other type.
Last updated October 11, 2026 · Sources: HomeGuide, “How Much Does a Sunroom Cost?” (2026); Angi, sunroom addition cost ($150–$300 per sq ft)
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Sunroom cost by size
Mid-range build level, using the published per-square-foot ranges for each type.
| Room | Area | Three-season | Four-season |
|---|---|---|---|
| 10 × 10 ft | 100 sq ft | $12,950 – $18,050 | $26,600 – $33,400 |
| 10 × 12 ft | 120 sq ft | $15,540 – $21,660 | $31,920 – $40,080 |
| 12 × 12 ft | 144 sq ft | $18,648 – $25,992 | $38,304 – $48,096 |
| 12 × 16 ft | 192 sq ft | $24,864 – $34,656 | $51,072 – $64,128 |
| 14 × 16 ft | 224 sq ft | $29,008 – $40,432 | $59,584 – $74,816 |
| 16 × 20 ft | 320 sq ft | $41,440 – $57,760 | $85,120 – $106,880 |
Three-season or four-season?
| Type | Per sq ft | What you get |
|---|---|---|
| Three-season room | $80–$230 | Glass or screen panels, little insulation, no heating or cooling. Spring to autumn use. |
| Four-season room | $200–$400 | Insulated walls and roof, double glazing, HVAC. Year-round living space. |
What moves the price
- Foundation. A new slab or footings is a big share of the cost; an existing deck or patio saves it only if it can carry the walls and roof.
- Glass. Low-E, double-pane glass costs more than single-pane or vinyl panels and is what makes a room usable in winter and summer.
- Roof tie-in. A roof that extends the house roof line costs more than a lean-to panel roof.
- HVAC and electrical. A ductless mini-split, outlets and lighting add to a four-season room.
Want something simpler? Compare the screened porch cost calculator, the porch cost calculator and the deck roof cost calculator.
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Frequently asked questions
- How much does a sunroom cost?
- About $80–$230 per sq ft for a three-season room and $200–$400 per sq ft for a four-season room (HomeGuide, 2026). A 12 × 12 ft (144 sq ft) room is roughly $11,520–$33,120 as a three-season room and $28,800–$57,600 as a four-season room.
- What is the difference between a three-season and a four-season sunroom?
- A three-season room has glass or screen panels but little or no insulation and no heating or cooling, so it is comfortable from spring to autumn. A four-season room is insulated, double-glazed and heated and cooled, so it can be used all year and is treated as part of the house for permits and energy code.
- How much does a 12x12 sunroom cost?
- A mid-range three-season 12 × 12 room is about $18,648–$25,992; a mid-range four-season room about $38,304–$48,096. Basic kits on an existing slab sit at the bottom of the range.
- Is it cheaper to put a sunroom on an existing deck?
- It can be, because you skip most of the foundation, but only if the deck's footings, beams and joists can carry walls, glass and a roof. Many decks can't without new footings; have them checked before you order a kit.
- Does a sunroom add value to a house?
- A four-season room that is heated and cooled usually counts as living space and adds more value than a three-season room. Check local comparable sales before you spend for resale.
- Is a screened porch cheaper than a sunroom?
- Yes, usually by a wide margin, because screens cost far less than glass and there is no HVAC. Price one with the screened porch cost calculator.
