Apartment Measurement

Are You Paying Too Much Rent? How Apartment Measurement Works in Germany

In Germany, apartment size (Wohnfläche) is calculated using specific legal standards — primarily the Wohnflächenverordnung (WoFlV) and DIN 277. If your apartment's actual measured area is more than 10% smaller than what's stated in your rental or purchase contract, you may be entitled to a rent reduction (Mietminderung) or price adjustment. Studies suggest that up to 70% of German apartments have incorrectly stated floor areas.

Why This Matters More Than You Think

The difference between advertised size and actual measured size isn't just an academic question—it directly impacts your wallet.

The rent calculation: Your rent is calculated per square metre. If you're paying €15/m² in Berlin and your apartment is advertised as 80m² but actually measures 75m², you're overpaying by 5m² × €15 = €75 every month. That's €900 per year on a discrepancy you didn't know existed.

Larger discrepancies compound: A more common scenario: a 2-bedroom apartment advertised as 85m² but actually 72m² (15% smaller). At €16/m² (typical for Berlin), you're paying €192/month too much. Over a 3-year tenancy, that's €6,912 in rent for space you don't have.

For buyers, it's even worse: A wrong Wohnfläche means you paid too much per square metre, and your resale value suffers equally. If you bought at €7,000/m² based on 85m² but it's actually 72m², you overpaid by roughly €91,000.

Measurement errors are common: Many Hausverwaltungen (property management companies) use old or incorrect measurements, sometimes dating back decades. Altbau (pre-WWII) apartments are especially prone to errors—odd layouts, sloped ceilings, and irregular wall placements make calculation complex.

WoFlV vs DIN 277 — The Two Standards Explained

Here's where the legal complexity—and many disputes—begin. Germany has two main standards for calculating living area, and they produce very different results.

Aspect	WoFlV (Wohnflächenverordnung)	DIN 277
Used for	Residential rentals & purchases	Commercial, new builds
Balcony/terrace	25–50% counted	100% counted
Rooms under 1m ceiling	0% counted	100% counted
Rooms 1–2m ceiling	50% counted	100% counted
Basement/cellar	Not counted	Counted as Nutzfläche
Result	Usually smaller	Usually larger
Legal basis	Standard for rent disputes	Often used by developers

The trick: Developers often advertise using DIN 277 (which gives larger numbers) for marketing purposes. But when calculating your rent, German law requires WoFlV. Many expats don't know this difference—they see "80m²" online and expect 80m² under WoFlV rules. The reality is 65-70m².

What Counts and What Doesn't Under WoFlV

Counts at 100%: Full-height rooms with ceilings over 2 metres. Kitchens, living rooms, bedrooms in standard apartments all count fully if ceiling height is adequate.

Counts at 50%: Rooms or areas with ceilings between 1–2 metres in height. This includes Dachschrägen (sloped ceilings) in top-floor apartments. A bedroom with a sloped roof that averages 1.5m tall counts for only half its floor area.

Counts at 0%: Areas under 1 metre of ceiling height. A 3m² storage nook under a stairwell with only 0.8m height contributes nothing to your Wohnfläche.

Balconies and terraces: Counted at 25% or 50% depending on whether they're enclosed and weatherproof. A 10m² open balcony counts as only 2.5–5m².

Unheated conservatories: Counted at 50% only if they connect to heated living space.

NOT counted: Cellars, garages, attics (unless they meet the height requirements above), stairwells outside your apartment.

Exception: Stairwells within the apartment are counted once (not per floor).

The 10% Rule — Your Legal Protection

This is the most important rule for tenants and buyers. Remember it.

The law (BGH ruling VIII ZR 144/09): If the actual measured Wohnfläche is more than 10% smaller than what your contract states, you have legal grounds for a Mietminderung (rent reduction) proportional to the difference.

Example calculation: Your Mietvertrag (rental agreement) states 75m². Professional measurement reveals 65m². The difference: 10m², or 13.3%. You can claim a 13.3% rent reduction retroactively. On €1,200/month rent, that's €160/month back—or €1,920/year.

Applies retroactively: You can claim back overpaid rent from when you first moved in, not just going forward. However, limitations apply (typically 3 years under German law for warranty claims).

For buyers: This can be grounds for price reduction under §437 BGB (German Civil Code). If you bought based on a false Wohnfläche, you can claim damages.

Below 10%: A 5% difference is annoying but not legally actionable. The 10% threshold is deliberate—it separates minor measurement variation from genuine fraud.

How to Check If Your Apartment is Correctly Measured

You don't need an expert initially. Start with a simple self-check using basic tools.

Step 1: Get a laser measure (Laser-Entfernungsmesser). Available from Bauhaus or online for €30–€50. It's accurate to ±2mm and measures distances instantly.

Step 2: Measure room by room. Measure length and width of each room at the widest/longest points. Note ceiling heights at the walls (where it matters for the 1-2m rule). Create a simple sketch or spreadsheet with room name, dimensions, and ceiling height.

Step 3: Apply WoFlV rules. For each room:

If ceiling ≥2m: count full area (length × width)
If ceiling 1–2m: count 50% of area
If ceiling <1m: count 0%
For balconies: count 25–50% of area

Step 4: Compare with your contract. Add up your calculated total and compare with your Mietvertrag or Kaufvertrag (purchase agreement).

Step 5: If >10% difference, get professional help. If your calculation suggests a discrepancy larger than 10%, don't rely on your DIY measurement alone. The next step is professional.

When to Get a Professional Wohnflächenberechnung

A professional measurement is your legal insurance policy.

Why independent measurement matters: A certified Sachverständiger (expert) produces a legally admissible report. German courts give this document significant weight in disputes. It removes ambiguity—either there's a measurement error or there isn't. No arguments, just data.

What a professional report includes: Precise laser measurements of every room and dimension, ceiling height verification at multiple points per room, photographic documentation, WoFlV calculation applied correctly, comparison with contract figure, and professional conclusion on whether a legal discrepancy exists (>10%).

Cost: A standalone Wohnflächenberechnung (floor area calculation) costs €200–€400. This is a bargain if it recovers months of overpaid rent or supports a purchase price claim. Alternatively, it's included in a full Baugutachten (building inspection), which costs €590–€800 and covers structural condition, mould, electrical safety, and more.

Turnaround: A standalone calculation takes 3–7 working days. You receive a PDF report suitable for submission to your landlord or in legal proceedings.

How it helps: Armed with a professional report showing a >10% discrepancy, your options are clear: your landlord either agrees to rent reduction immediately, or you escalate to legal action with a strong foundation. Most landlords settle once confronted with professional documentation.

When Size Really Costs You: Real Examples

Example 1 (Rent): A 2-bedroom in Kreuzberg, Berlin, advertised as 78m² at €14.50/m² = €1,131/month. Professional measurement: 68m² (12.8% discrepancy). Tenant can claim 12.8% rent reduction = €144.80/month. Over a 5-year tenancy: €8,688 back.

Example 2 (Purchase): A buyer in Charlottenburg pays €520,000 for an apartment advertised as 92m² (€5,652/m²). Post-purchase survey: 80m² (13% smaller). The buyer overpaid by approximately €67,600. Under German law, this grounds a price reduction claim.

Example 3 (Sloped ceilings): A top-floor Dachgeschoß apartment in Friedrichshain advertised as "75m² + 10m² loft space" sounds spacious. In reality, the loft has 1.2m average ceiling (sloped), so it counts as only 5m² under WoFlV. The true size is 70m², not 85m². The tenant is paying 12% more than justified.

Common Measurement Mistakes

Including hallways twice: Hallways (Flur) are counted once and distributed to adjacent rooms. Some old calculations double-count them.

Measuring at angles: Dimensions must be measured perpendicular to walls, not diagonally. Old measurements sometimes guess based on sketches.

Ignoring DIN 277 vs WoFlV difference: A property manager might have calculated using DIN 277 for advertising but then used that inflated figure in the contract. Illegal, but common.

Not documenting ceiling heights: Many old apartment measurements list dimensions but omit ceiling heights, making it impossible to apply the 1-2m rule correctly.

FAQ: Apartment Size in Germany

What is the difference between Wohnfläche and Nutzfläche? +

Wohnfläche (living area) is the usable floor space in a residential property—what you actually live in. Under WoFlV, only 50% of sloped ceiling areas under 2m count, and areas under 1m don't count at all. Nutzfläche (usable area) includes additional spaces like parking, storage, and common areas at full value. Nutzfläche is typically 10–15% larger than Wohnfläche.

Can I reduce my rent if my apartment is smaller than advertised? +

Yes. Under German law (BGH VIII ZR 144/09), if actual Wohnfläche is more than 10% smaller than your contract states, you can claim Mietminderung (rent reduction) proportional to the difference. If your contract says 80m² but your apartment is actually 70m², that's a 12.5% discrepancy, justifying a 12.5% rent reduction applied retroactively.

Does a balcony count towards Wohnfläche in Germany? +

Under WoFlV, balconies and terraces count for only 25–50% of their actual size, depending on quality and enclosure. Under DIN 277 (used for new builds and commercial valuations), they count at 100%. This is a major source of measurement discrepancies—many developers advertise using DIN 277 to inflate apparent size.

How much does a professional Wohnflächenberechnung cost? +

A certified Wohnflächenberechnung (floor area calculation) costs €200–€400 as a standalone service, or is included in a full Baugutachten (building inspection). This report is legally admissible for rent disputes and purchase price claims, making it essential insurance if you suspect measurement errors.

Do sloped ceilings (Dachschräge) reduce my Wohnfläche? +

Yes, under WoFlV. Rooms with ceilings between 1–2m in height count for only 50% of their floor area. Areas under 1m don't count at all. This dramatically reduces Wohnfläche in Dachgeschoß (top floor/attic) apartments. A developer might advertise 80m² but WoFlV calculation reveals only 65m².

What is the 10% rule for apartment size in Germany? +

Under German law (BGH ruling VIII ZR 144/09), if actual measured Wohnfläche is more than 10% smaller than what's stated in your rental or purchase contract, you have legal grounds for claims. A 10% difference is the threshold—below 10% is typically not actionable legally, but above 10% entitles you to rent reduction or price adjustment.

Your Next Steps

If you suspect your apartment is incorrectly measured:

1. Do a self-check first. Use your smartphone measure app or a €40 laser measure. If you find a potential discrepancy, document it.

2. Get professional confirmation. If your self-check suggests >10% difference, commission a Wohnflächenberechnung. The cost is trivial compared to potential recovery.

3. Notify your landlord formally. If professional measurement confirms a >10% discrepancy, send a formal letter (Einschreiben) referencing the measurement report and your rent reduction claim. Most landlords settle immediately rather than escalate.

4. If you're buying, request a measurement condition. Include "subject to professional measurement verifying stated Wohnfläche" in your Kaufvertrag before signing. This protects you from overpaying for missing square metres.

Get a Professional Wohnflächenberechnung →

A Wohnflächenberechnung can be included in any building inspection. Whether you're buying, renting, or already settled, we produce legally admissible floor area calculations. Get in touch →