Variance and discrepancy checks
How to check true square footage against an agent's floor plan claim
Square footage drives price per square foot, which drives almost every comparison you will make between properties. It is also one of the least standardised numbers in a UK listing — so it is worth knowing exactly where each figure came from before you trust it.
The three floor areas a property can have
- The EPC total floor area. Recorded in square metres by an accredited assessor during the energy assessment and lodged on the EPC register. It measures habitable internal area; unheated spaces such as an integral garage or an unconverted loft are generally excluded.
- The floor plan area. Produced by whoever drew the marketing plan. Many carry a disclaimer that they are illustrative and not to scale. Some include areas the EPC excludes.
- The listing text area. Sometimes copied from the floor plan, sometimes from a previous sale's particulars, occasionally rounded upward.
Convert before you compare
1 m² = 10.7639 sq ft. A 96 m² EPC figure is 1,033 sq ft. Comparing metres to feet by eye is how most "discrepancies" turn out to be arithmetic.
How to run the check
- Note the listing's stated area and its unit, and screenshot the floor plan including any disclaimer.
- Search the EPC register by postcode and open the certificate for the exact address. Record the total floor area and the inspection date.
- Convert to a single unit and calculate the difference as a percentage of the larger figure.
- Check whether the difference is explained: a conservatory, garage conversion, or outbuilding included in one figure and not the other; or an extension built after the EPC inspection date.
- Recalculate £/sq ft both ways. That spread is the practical size of the issue.
Reading the result
| Difference | How to read it |
|---|---|
| Under 5% | Measurement convention. Not a negotiation point. |
| 5–10% | Worth one question. Usually an excluded space or a rounding on the plan. |
| Over 10% | Ask which figure the agent stands behind, in writing, and check whether the EPC predates an extension. |
If the EPC is older than a visible extension, the EPC is simply out of date — that is not a discrepancy in your favour, and treating it as one will cost you credibility. Check the inspection date every time.
What it is worth
The honest answer is: it depends on what comparable properties in the postcode achieve per square foot. If registered sales nearby run at £420/sq ft and the correct area is 100 sq ft smaller than advertised, the arithmetic gap is around £42,000 — but only if the comparables are genuinely comparable in type, condition and tenure. Our guide to price per square foot negotiation covers how to build that comparison so it survives scrutiny.
For a definitive measurement, a RICS surveyor can measure to IPMS standards. For an offer-stage sanity check, the EPC-versus-listing comparison is usually enough.
Frequently asked questions
- Is the EPC floor area legally binding?
- No. It is a measurement taken by an accredited assessor for energy modelling purposes. It is evidence, not a warranty, and it can be out of date.
- Why do some listings show no floor area at all?
- There is no requirement to publish one. Absence is not suspicious in itself, but it does mean you have to rely on the EPC or measure at the viewing.
Sources
Check a property before you offer
Run any UK postcode through our free lookup for EPC bands, flood exposure, registered sold prices and recorded crime. Got a specific listing? Paste the Rightmove link for the full six-section FirstBid report.
Related guides
The complete guide to cross-checking a UK property listing against public records
A step-by-step method for testing every claim in a Rightmove or Zoopla listing against EPC, planning, flood and Land Registry records before you make an offer.
Using £ per square foot variance to justify a below-asking offer
How to calculate price per square foot from registered sold prices and EPC floor areas, choose fair comparables, and turn the variance into a defensible offer.
EPC rating discrepancies: what they mean for your bills and your mortgage
How to read an EPC properly, spot certificates that no longer describe the property, and work out what the gap costs in running costs and improvement work.