Flat Value Calculator
Estimate what a flat or apartment is worth from its size, the local rate per square foot, and four adjustments: bedrooms, condition, age, and a location premium. The result is a market-style estimate for buyers setting an offer or sellers sense-checking an asking price, not a formal valuation. One name note: “flat value” can also mean a fixed amount added to a price, a flat fee or flat discount. This page uses the property meaning, the value of a flat. If you wanted base price plus a fixed fee, that is simply base + fee.
An automated estimate, not a professional appraisal. Lenders and courts require a certified valuer; use this for orientation only.
Quick Answer
A 1,200 sq ft flat at a local rate of $250 per sq ft has a base value of $300,000. With 3 bedrooms (×1.05), good condition (×0.795), 10 years of age (×0.85) and a 5% location premium (×1.05), the estimate is $223,504.31, or $186.25 per sq ft, a net adjustment of -25.5% against the base. Those are the pre-filled inputs above, so one click reproduces every figure.
- Quick Answer
- How to use the Flat Value Calculator
- How the estimate is built
- Worked example, checked against this exact tool
- Getting the rate per sq ft right
- Age depreciation: a simplification, stated plainly
- What this estimate is not
- What competing calculators miss
- Frequently asked questions
- Add This Calculator to Your Website
- References
How to use the Flat Value Calculator
Start from recent comparable sales, not from the asking price. The tool multiplies size by rate, then applies the four adjustments in a fixed order and shows every step.
- Enter the flat size in square feet, on the same area basis as your comparables.
- Enter the local rate per sq ft from sold prices of similar flats nearby, ideally within about half a mile and the last 6 to 12 months.
- Set bedrooms and condition: pick the layout (studio to 5 bedrooms) and the honest condition grade. Both apply fixed multipliers, listed in the tables below.
- Enter the property age in years, 0 for new. Age deducts 1.5% per year, capped at 50%.
- Add a location premium only if it is real: a better street, view or transport link within the same rate area. Blank counts as 0, and if your comparables are next door, 0 is the right answer.
- Click Calculate: results stay hidden until you do. You get the base value, the estimated flat value, the value per sq ft, the net adjustment against the base, and a step-by-step formula line.
Size, rate and age are required and must be valid: size and rate above zero, age zero or more, and the location premium cannot be negative. Each failure stops with a specific message, such as “Flat size must be greater than zero”, instead of a silent wrong number.
How the estimate is built
The base is the comparison method valuers start from: size × local rate per sq ft, where the rate comes from recent comparable sales. Four adjustments then apply, each as a multiplier, in this order: bedrooms, condition, age, location.
| Bedrooms | Multiplier | Condition | Multiplier |
|---|---|---|---|
| Studio | 0.90 | Excellent | 0.975 |
| 1 | 0.95 | Very good | 0.895 |
| 2 | 1.00 | Good | 0.795 |
| 3 | 1.05 | Fair | 0.695 |
| 4 | 1.10 | Poor | 0.570 |
| 5 | 1.15 |
Two details in those tables surprise people. First, every condition setting is at or below 1.0, even excellent at 0.975: the local rate is assumed to describe a well-kept unit, so condition can only discount from there, never add a bonus above the comparable benchmark. Second, the final estimate is floored at 30% of the base value, so a distressed combination still returns a residual figure instead of collapsing toward zero. One display quirk follows from that floor: when it triggers, the formula line’s last step jumps straight to the floored figure, because the floor is applied after the location step. The step values before it are still the unfloored arithmetic.
Worked example, checked against this exact tool
A 1,200 sq ft flat where comparable units sell for $250 per sq ft: base value = 1,200 × 250 = $300,000. It has 3 bedrooms (×1.05 = $315,000), is in good condition (×0.795 = $250,425), is 10 years old (depreciation 15%, ×0.85 = $212,861.25), and sits in a sought-after block (location premium 5%, ×1.05). Estimated value: $223,504.31, or $186.25 per sq ft, a net adjustment of -25.5% against the base.
| Case | Inputs | Estimated value | Per sq ft | Net adjustment |
|---|---|---|---|---|
| Worked example | 1,200 sq ft, $250, 3 bed, good, 10 yr, +5% | $223,504.31 | $186.25 | -25.5% |
| New studio | 800 sq ft, $300, studio, excellent, 0 yr, 0% | $210,600.00 | $263.25 | -12.3% |
| Older large flat | 1,500 sq ft, $200, 5 bed, poor, 40 yr, +10% | $108,157.50 | $72.11 | -63.9% |
| Floor case | 500 sq ft, $100, 1 bed, poor, 100 yr, 0% | $15,000.00 | $30.00 | -70.0% |
The floor case is worth typing in yourself: the raw arithmetic gives $13,537.50 after the age step, and the 30% floor lifts the final estimate to $15,000.00, exactly 30% of the $50,000 base. Every row in this table was produced by running the calculator, not by hand-rounding a spreadsheet.
Getting the rate per sq ft right
The whole estimate pivots on this one input. A rate built from asking prices inflates everything downstream, because every multiplier acts on the base it creates.
Use sold prices of comparable flats within about half a mile, sold in the last 6 to 12 months, divided by their floor area. House price movements between those sales and today matter too: index series such as the FHFA House Price Index show how fast a market is moving, and in a fast-rising market a 12-month-old comparable understates value unless you weight recent sales heaviest. Keep the area basis consistent as well: carpet area for your flat against carpet-area comparables, built-up against built-up. For the official picture of the housing stock behind those comparables, the U.S. Census Bureau American Housing Survey and its Characteristics of New Housing series are the reference sources. How an assessed figure relates to market value is a separate question, covered by the assessed value to market value calculator.
Age depreciation: a simplification, stated plainly
Real depreciation is not a straight line. Resale patterns usually show the steepest drop in the first years, then a flattening curve as a building settles into its long-term discount.
This tool’s flat 1.5% per year, capped at 50%, is a deliberate simplification: easy to audit in the formula line and conservative for newer buildings. For a 20-year-old flat it deducts 30%. Treat the age factor as the roughest of the four adjustments, and lean on the rate per sq ft, drawn from comparables of a similar age, to absorb most of the age effect in serious estimates. The general mechanics of value falling over time are covered by the diminishing value depreciation calculator. Investors running the same flat as a rental rather than a purchase can cross-check the price against the approach in the buying rental property calculator.
What this estimate is not
It is not a formal valuation, a bank appraisal, or a substitute for comparable-market analysis by an agent who has walked the unit. Professional standards exist for that work, from the Appraisal Foundation’s USPAP standards to the International Valuation Standards, and lenders, courts and tax authorities require a certified valuer working to them.
The tool also ignores floor level, facing, view, parking, service charges, lease length and the undivided share of land, all of which move real prices. Fold floor and parking into your choice of comparables or the location premium where you can. Consumer guidance from the Consumer Financial Protection Bureau’s owning-a-home resources and HUD housing counseling covers the buying process around the number. Use this estimate to sanity-check a listing price or rank shortlisted flats, then get professional advice before offering.
Key takeaways
- The rate per sq ft decides the answer. Build it from recent sold prices nearby, on a consistent area basis, or every later adjustment polishes a bad base.
- Condition only discounts here: even excellent is ×0.975, because the rate already assumes a well-kept comparable.
- Age costs 1.5% per year up to a 50% cap, and the final estimate never falls below 30% of the base value.
- Leave the location premium at 0 unless the flat is genuinely better located than the comparables behind your rate.
What competing calculators miss
Search this keyword and you mostly find adjacent tools answering different questions:
- Price-per-square-foot tools (several rank for this term) divide a known price by area, or multiply a rate by area, and stop. Useful arithmetic, but there are no bedroom, condition, age or location adjustments, so two flats of the same size in the same block price identically no matter their state.
- Rental-method apartment valuers (for example the GRM approach, monthly rent × 12 × a gross rent multiplier) value income, not the unit. They need a rent figure and a multiplier you have to source yourself, and they say nothing about an owner-occupied flat with no rent.
- Fixed-amount “flat value” tools add a flat fee or discount to a base price. A different meaning of the same phrase, flagged in the first paragraph here instead of being left for the reader to trip over.
- The gap this page fills: size × rate with all four adjustments in one free tool, every multiplier published in tables on the page, and a formula line that shows the running value after each step so you can audit the estimate instead of trusting it.
Frequently asked questions
A tool that estimates a flat or apartment’s market value from its size, the local rate per square foot, and adjustments for bedrooms, condition, age, and location. The phrase can also mean a fixed-amount pricing tool (base price plus a flat fee); this page covers the property meaning.
It is an orientation figure, and its accuracy lives or dies with the rate per sq ft you enter. Built from genuine recent comparable sales, it gives a sensible screening estimate; built from asking prices or stale sales, it will be off by roughly whatever the rate is off by. It is not a substitute for a professional valuation.
Because the local rate per sq ft is assumed to describe a well-kept comparable unit, so condition acts as a discount from that benchmark rather than a bonus above it. Excellent is 0.975, good is 0.795, and poor is 0.570.
Whichever your comparables use, consistently. Enter your flat’s size and build the rate per sq ft on the same basis, carpet area with carpet area or built-up with built-up. Mixing them is the most common source of skewed results.
The tool deducts 1.5% per year of building age, capped at 50%. A 10-year-old flat keeps 85% of its adjusted value. It is a simplification: real depreciation usually falls fastest in the first years and then flattens.
Your judgment uplift for a better street, view, transport access, or block within the same rate area, entered as a percentage. If your comparables are truly next door, leave it at 0. A blank entry also counts as 0, and the premium cannot be negative.
No. There are no separate inputs for floor level, facing, view, or parking. Fold those into the rate per sq ft by choosing comparables with similar floor and parking, or into the location premium.
The bedroom and condition logic transfers, but houses price land separately from the building, and this tool has no land component. A dedicated house valuation method fits better.
To keep distressed combinations, such as a very old flat in poor condition, returning a plausible residual value instead of approaching zero. If the adjusted estimate falls below 30% of the base value, the tool reports 30% of the base instead.
No. Lenders, courts, and tax authorities require a certified valuer. This is a screening estimate for orientation, shortlisting, and sense-checking an asking price.
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References
- Federal Housing Finance Agency. House Price Index. Accessed October 21, 2026.
- U.S. Census Bureau. American Housing Survey. Accessed October 21, 2026.
- U.S. Census Bureau. Characteristics of New Housing. Accessed October 21, 2026.
- U.S. Bureau of Labor Statistics. Consumer Price Index: Owners’ Equivalent Rent and the House Price Index. Accessed October 21, 2026.
- Consumer Financial Protection Bureau. Owning a Home. Accessed October 21, 2026.
- U.S. Department of Housing and Urban Development. Housing Counseling. Accessed October 21, 2026.
- The Appraisal Foundation. Uniform Standards of Professional Appraisal Practice (USPAP). Accessed October 21, 2026.
- International Valuation Standards Council. International Valuation Standards. Accessed October 21, 2026.
- RICS. Valuation Standards and Guidance. Accessed October 21, 2026.
- National Association of Realtors. Research and Statistics. Accessed October 21, 2026.