HOME PLANNING MODULEHOME-ADDITION-VALUE-GAP-CALCULATORMODEL · COMPARE · DECIDE
Home Planning · reviewed September 11, 2026
Home Addition Value Gap Calculator
Compare a home addition’s project cost with your own before-and-after home value estimates to see cost per added square foot, estimated value added and recapture.
Quick answer
Home Addition Value Gap Calculator
The calculator does not predict home value. It only turns your own before/after estimates into a transparent value-gap and recapture calculation.
Formula: Estimated value added = after-project value − current value. Recapture = estimated value added ÷ project cost.
Finished area added by the project.All-in project budget you want to evaluate.Your own current-value estimate.Your own after-project value estimate.Optional value you want to recognize from staying instead of moving.
Enter your numbers and calculate.
How the calculation works
Estimated value added = after-project value − current value. Recapture = estimated value added ÷ project cost.
Every rate, percentage, cost and value assumption shown in the calculator can be changed. Results are scenario math based on your inputs, not quotes, appraisals, code determinations or predictions.
Questions people ask
What is recapture?
Your entered estimated value added divided by project cost.
Does a recapture below 100% mean the addition is a bad idea?
Not necessarily. The tool only compares entered project cost with entered property-value change; it does not value lifestyle benefits.
Does the calculator estimate my after-project value?