Almost every property valuation comes down to one question: what did buyers recently pay for homes like this one? The sales you use to answer it are called comparable sales, or comps, and finding the right ones is the single highest-leverage skill in pricing a home. Get your comps right and the rest of a valuation almost writes itself. Get them wrong and every clever adjustment afterwards just polishes a flawed number. This guide shows you where to find comps, how to judge which ones count, how many you need and how to adjust them into a figure you can defend.
A comp is not just any nearby house that sold. It is a property similar enough to your subject that what someone paid for it tells you something reliable about what your subject is worth. Three things drive that similarity: location, property type and size, and recency. A four-bedroom detached house that sold last week two streets away is a strong comp for another four-bedroom detached house. A studio flat across town that sold two years ago is not, no matter how cheap it makes your search. Before you gather anything, write down the subject property's key attributes: living area, plot size, bedrooms and bathrooms, build year, condition, outdoor space, parking and energy efficiency. Those are the yardsticks you will measure every candidate against.
Where to find comparable sales
The good news is that sold-price data is more open than ever. The most common sources, roughly in order of how clean the data is:
The multiple listing service (MLS), where one exists. For agents this is the richest source: confirmed sale prices, dates, photos and full property detail in one place.
Public sold-price registries and land registry records. Many countries publish actual transaction prices. They are authoritative on price and date, though often thin on the property's features.
Property portals. The "sold" and "price history" sections of the big listing sites pair the asking price and photos with the eventual sale, which helps you judge condition.
Automated valuation tools. These pull the above together and surface likely comps automatically, saving the hours that manual gathering costs.
Whatever the source, you want the actual sold price, not the asking price. Asking prices tell you what sellers hoped for; sold prices tell you what the market agreed to. The gap between the two is itself a useful market signal, but only the sold figure belongs in your estimate.
The three filters that separate good comps from noise
Location, tight then tighter
Start at the same street or block and widen only as far as you must. The moment you cross something buyers price differently — a main road, a district line, a different school catchment — your comp loses force. Proximity on a map is not the same as comparability in a buyer's head.
Similarity of the home itself
Match property type first (detached, terraced, apartment), then size, then layout and condition. A renovated three-bedroom and a tired three-bedroom of identical floor area can sell tens of thousands apart. The closer the match, the smaller the adjustments you will have to make later, and the less room for error.
Recency
Prefer sales from the last three months. In a thin market you may have to reach back further, but then you must adjust for how prices have moved since the sale closed. A stale comp treated as current is one of the most common ways a valuation drifts off the market.
How many comps you actually need
Three to six solid comparable sales is the working standard. With fewer than three, a single unusual sale can drag your whole estimate off; with many more, you are usually scraping in weak matches that add noise rather than confidence. Alongside your sold comps, glance at a couple of active listings to see your current competition and one or two expired ones to learn what the market refused to pay. Solds tell you where the market was; actives and expireds tell you where it is right now. This is the same evidence base behind a full comparative market analysis, just viewed through the narrow lens of choosing comps well.
A worked example
Suppose you are valuing a 95 m² two-bedroom apartment in good condition. You gather three recent sold comps from the same building and the street behind it:
Comp A: 95 m², same building, sold three weeks ago for €352,000 — but with a renovated bathroom your subject lacks. Adjust down €6,000 → €346,000.
Comp B: 88 m², next street, sold last month for €325,000. Add roughly €18,000 for the extra 7 m² → €343,000.
Comp C: 102 m², same block, sold two months ago for €368,000. Adjust down about €20,000 for the size difference → €348,000.
The three adjusted figures cluster between €343,000 and €348,000 — a tight band that gives real confidence. You would value the apartment around €345,000, with evidence to defend anything up to roughly €348,000. These figures are illustrative; the discipline is what matters. When three independent comps converge after adjustment, you have a number you can stand behind in front of a seller or a lender.
Comps that look good but lie
A few warning signs that a tempting comp should be set aside:
A sale between family members or any non-arm's-length deal, which rarely reflects open-market value.
A distressed or forced sale (repossession, urgent relocation), which usually trades below true value.
A property that sold furnished or with extras bundled into the price, inflating the headline figure.
An unusually long or short time on market, which hints the price was wrong in one direction.
None of these are automatically disqualifying, but each needs a reason before you lean on it. The point of finding comps is not to collect the most flattering number; it is to find the honest one.
Turning comps into a defensible value
Once you have your shortlist, adjust each comp up or down for how it differs from the subject, discard outliers you cannot explain, weight the closest matches most heavily and derive a range rather than a single figure. That range is the heart of any valuation, whether you are an agent pricing a listing or a buyer working out what to offer on a home.
The slow part is never the maths — it is gathering, filtering and adjusting the comps by hand, which can swallow an hour or more per property. Biedradar is built to remove exactly that grind: you enter an address and it pulls comparable sales, valuation and market signals, then produces an automated, branded property analysis report in minutes. The comps are surfaced and adjusted for you, so your time goes into judgement and the client conversation instead of spreadsheet wrangling. If you want to see how those comps feed a full report and which tools handle it well, our guide to choosing CMA software covers the data and features that matter.
Frequently asked questions
What is a comparable sale (comp)?
A comparable sale, or comp, is a property similar to the one you are valuing that recently sold. By looking at what buyers actually paid for homes alike in location, size, type and condition, you estimate what the subject property is worth today. Comps are the foundation of both a comparative market analysis (CMA) and a buyer's offer strategy.
How recent should a comp be?
As recent as you can find. In a fast-moving market, aim for sales that closed in the last three months; in a slow or thin market you may have to stretch to six or even twelve months, but then adjust for how prices have moved since. A sale from over a year ago is context, not evidence.
How far away can a comp be?
Stay as tight as possible: the same street or block is ideal, then the same neighbourhood, then the same school catchment or postal area. Cross a boundary that buyers price differently — a busier road, a different district, the wrong side of a river — and the comp stops being comparable, however close it looks on a map.
Where can I find comparable sales for free?
Public sold-price registries, land registry records and the sold or price-history sections of property portals are free in most markets. Agents also use the multiple listing service (MLS) where one exists. The data is the same raw material professional tools use; the difference is the time it takes to gather, filter and adjust it.
How many comps do I need?
Three to six strong comparable sales is the working standard. Fewer than three and one odd sale skews your whole estimate; far more than six and you are usually padding with weak matches. Quality beats quantity: three genuinely similar recent sales are worth more than a dozen loose ones.
