How to Adjust Comparable Sales: Line-by-Line Comp Adjustment Guide
No two properties are identical, which means raw comparable sales always need adjustment. A comp with 4 bedrooms selling for $280K does not mean your 3-bedroom subject is worth $280K. Adjusting comps for differences is what turns a list of sales into an accurate ARV estimate.
The adjustment principle
You always adjust the comp to match the subject property, never the other way around. If the comp has a feature the subject does not (extra bedroom, pool, garage), subtract value from the comp price. If the subject has a feature the comp does not, add value to the comp price.
Standard adjustment amounts
| Feature | Adjustment per Unit | Direction |
|---|---|---|
| Bedroom | $3,000-$7,000 | Per bedroom difference |
| Bathroom | $2,000-$5,000 | Per bathroom difference |
| Square footage | $15-$50/sqft | Per sqft difference (varies by market) |
| Garage | $5,000-$15,000 | Per garage space |
| Pool | $10,000-$25,000 | Presence/absence |
| Lot size | $1-$5/sqft | For significant differences only |
| Age/year built | $500-$2,000/year | For significant age differences |
| Condition | Varies | Renovated vs dated: $10K-$50K+ |
These ranges vary significantly by market. A bedroom in Houston adds $5K. In San Francisco, it adds $25K+. Use local data to calibrate your adjustment amounts.
Example adjustment
Subject: 3 bed / 2 bath, 1,500 sqft, no pool, 2-car garage
Comp: 4 bed / 2 bath, 1,700 sqft, pool, 2-car garage, sold for $310K
| Adjustment | Amount |
|---|---|
| Extra bedroom (comp has 4, subject has 3) | -$5,000 |
| Extra sqft (200 sqft x $25) | -$5,000 |
| Pool (comp has, subject does not) | -$15,000 |
| Garage (same) | $0 |
| Adjusted comp value | $285,000 |
When adjustments get too large
If your total adjustments exceed 15-20% of the comp's sale price, the comp is not a good match. Find a better comp. Large adjustments reduce confidence in the estimate because each adjustment introduces uncertainty.
Condition adjustments
The hardest adjustment to quantify. A renovated comp selling for $300K tells you what a renovated property is worth. If your subject is not renovated, you need to subtract the cost of renovation. This is why repair estimates are critical — they inform your condition adjustment.
Related guides
- How to Run Comps
- How to Calculate ARV
- Using MLS for Comps
- How to Value a Fixer Upper
- How to Analyze Any Deal