UNDERSTAND YOUR ESTIMATE
How this calculator works
Multiply the new floor area by the published range for the selected room type. Selecting the second floor uses the second-story rate in place of the room rate. This avoids stacking two construction budgets for the same area.
Major factors affecting the result
- Area and room type determine the base construction range.
- Second-story work uses its own rate rather than an invented surcharge.
- Plumbing, foundation conditions and finish choices need a project-specific scope.
Put the numbers in context
A 200 sq ft bedroom addition: 200 × $125–$175 = $25,000–$35,000. Its midpoint is $30,000 before separately quoted extras.
What is not included
Land purchase, financing, temporary accommodation and separately quoted design or permit fees. Finish, plumbing and HVAC adjustments are not independently quantified.
When to get a professional quote
Use the result to organize your questions and compare the same scope across written quotes. Confirm inclusions, exclusions and site conditions with the person doing the work. For structural, electrical, HVAC or tree-hazard decisions, consult a qualified professional.
Frequently asked questions
Can I estimate a second-story addition?
Yes. Choose second-story addition or second floor. The calculator uses one second-story rate and does not add another first-floor baseline.
Does this show whether my house can support another story?
No. A qualified design and structural team must assess the existing building and local requirements.
Data sources & methodology
Last reviewed: September 2026.
Low and high use the linked published ranges. Typical is the arithmetic midpoint only when both bounds are closed. If a source prints an upper value with “+”, Typical is not calculated. No regional, material-quality or difficulty multiplier is applied. Source ranges may describe different scopes and should not be treated as guarantees.
Bedroom
$125–$175 per sq ft · HomeGuide cost guide
Room-type table; new addition, not a conversion.
Published January 8, 2024 · Accessed September 16, 2026 · Typical: derived midpointBathroom
$175–$225 per sq ft · HomeGuide cost guide
Room-type table; new addition, not a conversion.
Published January 8, 2024 · Accessed September 16, 2026 · Typical: derived midpointFamily room
$125–$175 per sq ft · HomeGuide cost guide
Room-type table; new addition, not a conversion.
Published January 8, 2024 · Accessed September 16, 2026 · Typical: derived midpointKitchen
$200–$250 per sq ft · HomeGuide cost guide
Room-type table; new addition, not a conversion.
Published January 8, 2024 · Accessed September 16, 2026 · Typical: derived midpointSunroom
$100–$350 per sq ft · HomeGuide cost guide
Room-type table; new addition, not a conversion.
Published January 8, 2024 · Accessed September 16, 2026 · Typical: derived midpointGarage
$35–$60 per sq ft · HomeGuide cost guide
Site-built attached garage comparison. Basic garage without living space; not a garage conversion.
Published January 21, 2026 · Accessed September 16, 2026 · Typical: derived midpointSecond-story addition
$200–$500+ per sq ft · HomeGuide cost guide
Second-story band replaces the first-floor rate; includes finishing. Source high end is $500+.
Published January 8, 2024 · Accessed September 16, 2026 · Typical: not calculated (open-ended range)Itemized charges without a verified, non-overlapping basis remain unpriced. “Quote needed” does not mean free. An installed baseline is never silently split into invented cost percentages.