Why Comping Mistakes Are So Costly
Every real estate investment decision starts with comps. If your comparable sales analysis is flawed, every number that follows — ARV, maximum offer, profit projection — is wrong too.
These are the six most common comping mistakes we see investors make, along with how to fix each one. For a full walkthrough of the right process, see our guide on how to run real estate comps.
1. Using Listings Instead of Sold Prices
Active listings and even pending sales are not comps. They reflect what sellers are hoping to get, not what the market is actually paying. Only closed sales (sold prices) reflect true market value.
Active listings can be useful as supplementary data — they show current competition and market sentiment — but they should never replace sold comps in your valuation.
2. Picking Comps That Are Too Far Away
A property 2 miles away might be in a completely different neighborhood, school district, or price bracket. Distance matters because real estate values are hyper-local.
- Urban/suburban: Stay within 0.25–0.5 miles
- Rural: You may need 1–3 miles, but match the community character
- Never cross: Major highways, railroad tracks, or school district boundaries without adjusting
3. Ignoring Condition Differences
Comparing a fully renovated property to a dated one without adjustments will skew your valuation significantly. Condition is one of the hardest factors to quantify, but it's also one of the most impactful.
When estimating ARV, make sure your comps sold in a similar condition to your property's planned after-repair state.
Let AI handle the comp selection
Revaluno's Comps Tool applies consistent filtering criteria and AI-driven adjustments to eliminate human bias from your analysis.
Try the Comps Tool
4. Over-Adjusting Instead of Finding Better Comps
If you need to adjust a comp by more than 20–25% of its sale price, it's probably not a good comp. Over-adjusted comps introduce compounding errors that make your valuation unreliable.
The fix: expand your search slightly (wider radius or longer time frame) to find properties that need fewer adjustments. A slightly older sale with fewer adjustments is often more reliable than a recent sale adjusted heavily.
5. Cherry-Picking the Highest Comp
This is the most dangerous mistake, especially for new investors eager to make a deal work. Selecting only the highest-priced comparable sale to justify an inflated ARV is a recipe for losses.
Instead, use a weighted average of your best 3–5 comps. Give more weight to the most similar properties. If the deal doesn't work at a conservative ARV, it's not a good deal.
6. Using Outdated Sales Data
Markets shift. A comp from 12 months ago may not reflect current pricing, especially in volatile or rapidly appreciating/depreciating markets.
- Ideal: Comps from the last 3 months
- Acceptable: 3–6 months
- Use with caution: 6–12 months (adjust for market trends)
- Avoid: Anything older than 12 months
For more on the differences between valuation methods, see our comparison of CMA vs appraisal vs BPO.
Frequently Asked Questions
How many comps should I use?
Use 3–6 comparable sales. Fewer gives you too small a sample; more than 6 usually means you're including weaker matches that dilute accuracy.
What's the biggest comping mistake investors make?
Cherry-picking the highest comp to justify a deal. This leads to inflated ARV estimates and deals that lose money. Use a weighted average of your best comps instead.
Can software help me avoid comping mistakes?
Yes. AI-powered tools like Revaluno automate comp selection and apply consistent filtering criteria, reducing the human bias that causes most comping errors.