One of the most important steps in evaluating a fix and flip deal is pulling reliable comparable sales. Comps directly influence your after-repair value estimate, which affects how much a lender will finance and how much profit the project can realistically produce. As a result, learning how to run comps for a flip accurately helps you avoid overpaying for a property and gives lenders confidence in your deal.
This playbook explains how to find, evaluate, and present comparable sales that support a realistic ARV.
What Comparable Sales Are and Why They Matter #
Comparable sales are recently sold properties that closely match the subject property in location, size, condition, and type. Lenders and appraisers use them to determine what a property is worth after renovations are complete. Specifically, comps matter because:
- They form the basis for your ARV estimate
- Lenders use them to decide how much they are willing to lend
- Inflated or poorly selected comps lead to inaccurate projections
- A weak comp set can cause an appraisal to come in lower than expected
Strong comps reduce risk for both you and the lender.
Where to Find Comparable Sales Data #
There are several sources investors use to pull comps, depending on market access and available tools. For example, common sources include:
- MLS access through a real estate agent
- Public record databases and county assessor websites
- Platforms like Zillow, Redfin, or Realtor.com for recent sales data
- Paid investor tools such as PropStream or BatchLeads
MLS data tends to be the most accurate and detailed. If you do not have MLS access, working with an agent who can pull comps for you is a reliable alternative.
How to Filter for Relevant Comparables When You Run Comps for a Flip #
Not every recent sale qualifies as a strong comp. To build a credible ARV estimate, you need to filter your search carefully. In particular, key filters to apply include:
- Proximity: Ideally within 0.5 miles, no more than 1 mile in most markets
- Recency: Sold within the last 3 to 6 months
- Size: Within 10 to 15 percent of the subject property’s square footage
- Property type: Match single-family to single-family, condo to condo, and so on
- Condition: Focus on renovated or updated properties that reflect what your finished product will look like
Additionally, avoid using comps that sold under distressed conditions such as foreclosures, short sales, or estate sales unless you adjust for those factors.
How to Adjust Comps for Differences #
No two properties are identical, so adjustments are a normal part of the comp analysis. The goal is to account for meaningful differences between the comp and your subject property. For instance, common adjustments include:
- Square footage differences
- Bedroom or bathroom count
- Lot size
- Garage or parking
- Year built or major upgrades
- Location within the neighborhood
Adjustments should be conservative and based on local market data. Avoid inflating adjustments to justify a higher ARV.
How Many Comps You Need #
Most lenders and appraisers prefer to see at least three strong comparable sales. In some cases, providing four or five gives additional support to your estimate. When selecting your final comp set:
- Choose the three to five most relevant sales
- Prioritize comps that are closest in proximity, recency, and condition
- Include at least one comp that is slightly below your estimated ARV to show a range
- Avoid cherry-picking only the highest sales
A balanced comp set shows the lender that your ARV is grounded in real market data, not optimistic assumptions.
Common Mistakes When Running Comps #
Investors sometimes weaken their deals by making avoidable comp selection errors. Therefore, mistakes to watch for include:
- Using comps from a different neighborhood or school district
- Relying on active listings instead of closed sales
- Including comps that are too old or too far away
- Ignoring condition differences between the comp and the planned renovation
- Choosing only the highest comps to inflate ARV
Accurate comps are not about picking the best-case scenario. They are about proving what the market actually supports.
Summary #
Running comps for a fix and flip project is one of the most critical parts of deal analysis. When you learn to run comps for a flip using tight filters, honest adjustments, and a balanced selection, you create an ARV estimate that holds up under lender review and helps protect your profit margin. Consequently, strong comps lead to better financing outcomes and fewer surprises at the appraisal stage.