How to Use Comparable Sales to Estimate Property Value

The most reliable way to estimate what a property is worth is to find what similar properties have actually sold for. This is the comparable sales approach — and it rests on one principle: evidence before estimate.

What Makes a Good Comparable

A comparable sale is a recent transaction of a similar property in the same market. The more similar the property and the more recent the sale, the stronger the evidence.

Look for comparables that match on:

• Location — same neighborhood, ideally within a few blocks
• Property type — same structure (duplex vs. single-family, etc.)
• Size — similar square footage and lot size
• Age and condition — similar construction era and upkeep
• Unit count and layout — same number of bedrooms and bathrooms
• Sale date — ideally within the last 3–6 months

Adjustments, Not Averaging

No two properties are identical. You don't average comparable sale prices — you adjust them.

If a comparable sold for $200,000 but has a renovated kitchen yours doesn't, subtract the value of that renovation. If it has one fewer bathroom, add the value of a bathroom. The goal is to estimate what each comparable would have sold for if it were exactly like your subject property.

Adjusted Comparable Price = Sale Price ± Adjustments

Weighting

Not all comparables deserve equal weight. A sale from last month around the corner is stronger evidence than one from eight months ago across town. Weight your comparables by:

• Recency of the sale
• Proximity to the subject property
• Similarity of the property
• Reliability of the data

Exclusions

Exclude sales that aren't arm's-length transactions: family sales, foreclosures, short sales, or distressed sales. They don't reflect market value.

Three Numbers, Not One

When you're done, you should have a range — not a single number. The low end is your conservative estimate. The high end is your optimistic estimate. The middle is your most likely estimate.

• Asking price is the seller's number.
• Market value is the evidence-based number.
• Investor price is your number — what the property is worth to you given your required return.

The Principle

Never ask only what a property is worth. Ask worth for what purpose.

A property's value depends on the question being asked — sale, rent, or hold. The comparable sales approach answers the sale question. For the rent question, use rental comparables. For the hold question, use income approach (cap rate). Different questions, different evidence, different answers.