Home Addition Cost Calculator
Estimate room addition cost per square foot.
Home Addition Cost
What This Calculator Does
The Home Addition Cost Calculator estimates the cost of adding living space to your home based on the addition size, room type, and 2026 US national average contractor rates. Enter the addition square footage and select the room type to get a cost range.
Home additions are major construction projects that increase both living space and property value. They cost significantly more per square foot than basement finishing because they require new foundations, roofing, and weather-resistant exterior construction. First-floor additions generally cost less than second-story additions.
How to Use
- Measure the planned addition area in square feet.
- Select the addition type - first-floor room, master suite, or second-story addition.
- Select the finish level - standard or premium.
- Click "Calculate" to see the total cost estimate.
- Add 20-30% contingency for site conditions and permit delays.
Reference Table
| Addition Type | 200 sq ft | 400 sq ft | 600 sq ft | Timeline |
|---|---|---|---|---|
| First-Floor Room | $30K-$60K | $60K-$120K | $90K-$180K | 8-16 weeks |
| Master Suite | $50K-$100K | $80K-$160K | $120K-$240K | 12-20 weeks |
| Second-Story | N/A | $100K-$200K | $150K-$300K | 16-30 weeks |
Related Calculators
Garage Cost Calculator
Estimate garage construction cost for attached or detached garages.
Framing Calculator
Calculate studs, plates, and headers needed for wall framing.
Drywall Calculator
Calculate how many drywall sheets needed for a room.
Insulation Calculator
Calculate insulation batts or rolls needed for walls and attics.
Frequently Asked Questions
💰 Cost Estimators
Explore all 26 cost estimators