Breitbandmessung step by step: how to get a refund for slow internet in Germany under Section 57 TKG

The Bundesnetzagentur's Breitbandmessung is how you prove that your internet is too slow. Only its measurement report counts as evidence for a price reduction (Minderung) or a termination without notice under Section 57(4) TKG; an ordinary speed test in your browser is not enough. For home broadband you need 30 measurements on three days with the desktop app. For mobile contracts there has been a separate verification procedure since 20 April 2026, using an app and 30 measurements on five days.

Key points at a glance

• Only the Bundesnetzagentur's measurement report counts as proof: from the desktop app (home broadband) or from the app "Breitbandmessung Nachweisverfahren Mobilfunk" (mobile). Both apps are free.
• Home broadband: 30 measurements on three calendar days within 14 days, with a LAN cable to the router. A shortfall in download or upload under one of three criteria is enough.
• Mobile: General Ruling (Allgemeinverfügung) 35/2026 has applied since 20 April 2026. Your plan is too slow if, on at least three of five measurement days, it never reaches 25, 15 or 10 percent of the estimated maximum speed, depending on household density.
• In the 2024/2025 Breitbandmessung annual report, only 45.9 percent of users on home broadband got the full contracted download speed, and 85.9 percent got at least half.
• You enforce the reduction yourself with your provider. The Bundesnetzagentur's dispute resolution (Schlichtung) is free but currently takes well over six months.

What is the Breitbandmessung and when do you need it?

The Breitbandmessung is the Bundesnetzagentur's official speed measurement at breitbandmessung.de. The browser test gives you a quick impression; to get money back you need the verification procedure with an installed app.

Section 57(4) TKG gives you the right to reduce your payment or cancel without a notice period if the speed deviates from the contract values in a way that is "significant, continuous or regularly recurring". A monitoring mechanism provided or certified by the Bundesnetzagentur has to establish the deviation. The agency defines what counts as significant in general rulings: for home broadband in ruling 99/2021, in force since 13 December 2021, and for mobile in ruling 35/2026.

The tenth Breitbandmessung annual report, published on 18 June 2026, shows why measuring is worth it. It analysed 184,452 home broadband measurements from October 2024 to September 2025. 45.9 percent of users reached or exceeded the contracted maximum download speed, and 85.9 percent got at least half of it. More than half of users are therefore below the maximum. You only have a claim, though, once one of the criteria below is met.

The three speeds your contract guarantees are in the product information sheet. For a short overview of your rights when the internet is too slow, see Internet too slow. This article covers how the measurement works, the mobile rules and how the reduction is calculated.

How does the Breitbandmessung work for home broadband?

You install the desktop app from breitbandmessung.de on a Windows, macOS or Linux computer and start a measurement campaign. The app guides you through 30 measurements and produces a signed measurement report at the end.

1. Look up your contract values: note the minimum, the normally available and the maximum speed for download and upload.
2. Connect your computer with a LAN cable: measure directly at the router, not over WLAN (Wi-Fi), a repeater or powerline. An older network card can be the bottleneck on plans above 100 Mbit/s, so check it first.
3. Switch off anything that uses bandwidth: no downloads, streams, updates or VPN during the measurement. Turning off WLAN on the router stops other devices from using the line.
4. Plan your measurement days: ten measurements per day, at least five minutes between two measurements and at least three hours between the fifth and sixth. There must be a full calendar day between each of the three measurement days, all within 14 days.
5. Save the report: after the 30th measurement the app shows whether there is a shortfall (Minderleistung) and creates the report as a PDF.

A measurement campaign therefore takes at least five calendar days. If you only have time in the evening, do the first round in the early evening and the second three hours later. That way you also capture the hours when many households are online at once.

When is your home broadband officially too slow?

One criterion is enough, for download or upload separately. The Bundesnetzagentur checks all three contract values.

Contract value	Too slow if	Example 250 plan
Maximum	90% reached on fewer than 2 of 3 days	225 Mbit/s on 1 day only
Normal	reached in fewer than 90% of measure­ments	below 200 Mbit/s in 4 of 30
Minimum	under­cut on 2 of 3 days	below 150 Mbit/s on 2 days

The example assumes a plan with 250 Mbit/s maximum, 200 Mbit/s normal and 150 Mbit/s minimum. For the normal speed, no more than three of 30 measurements may fall below it. Four slow measurements already establish a shortfall.

Even when everything is fine, the desktop app produces a measurement report. In that case it records that there is no shortfall. If your result is a near miss, you can start a new campaign, for example after replacing your router or if the problems mainly occur in the evening.

Does the reduction also apply to your mobile contract?

Yes, since 20 April 2026. General Ruling 35/2026 sets out when mobile internet is significantly too slow. The benchmark is the estimated maximum speed in your contract.

Your plan counts as too slow if, on at least three of five measurement days, it does not reach a certain share of that speed at least once. The share depends on the household density where you measure. For this, the Bundesnetzagentur divides Germany into grid cells of 300 by 300 metres.

Area	Threshold	With 300 Mbit/s in the contract
High household density	25%	75 Mbit/s
Medium household density	15%	45 Mbit/s
Low household density	10%	30 Mbit/s

The campaign consists of 30 measurements on five days within 14 calendar days, no more than six per day, with at least three hours between the third and fourth measurement. According to the Bundesnetzagentur's guidance note, the app checks before each measurement that you are on at least 4G, not on a call, standing still (no more than 4 metres per second) and located to within 30 metres. Otherwise the measurement is blocked or discarded. For mobile, you only get a report if a shortfall is proven.

Mobile connections used at a fixed location, such as a 5G router at home, are excluded. The Bundesnetzagentur has announced a separate procedure for them but has not given a date yet.

How much can you reduce your bill?

The law sets no fixed amount. Under Section 57(4) sentence 2 TKG, the contract price is reduced "in the proportion" by which the actual performance deviates from the agreed performance.

The TKG does not say exactly which values to compare. The Verbraucherzentrale (consumer advice centre) offers a reduction calculator, with separate versions for home broadband and mobile. It takes the values from your measurement report and generates a letter to your provider (in German).

Worked example (assumptions): You pay 40 euros a month for a plan with a normal speed of 200 Mbit/s. In the report, your download measurements average 120 Mbit/s, which is 60 percent. If you compare these two values, a 40 percent reduction would be appropriate: 16 euros a month, 192 euros a year. Whether your provider or a court accepts this reference value is open.

Two rules work in your favour. Once the shortfall is proven, the reduction continues until the provider shows that it is delivering the contracted service again. If your connection goes down completely, compensation under Section 58 TKG is offset against the reduction. How that compensation works is explained in Compensation for outages.

What do you do if your provider does not respond?

Send your provider the measurement report with a written statement and a deadline. If it refuses, you can cancel, go to the dispute resolution body or take it to court.

The Bundesnetzagentur does not enforce individual reductions; you have to do that yourself. The report should be recent: for mobile, the agency advises presenting it when it is no more than four weeks old. Pay the part of the bill that is not in dispute and withhold only the reduced amount.

For termination without notice, Section 57 TKG refers to Section 314(2) BGB (Civil Code). So you first give the provider a reasonable deadline to fix the problem. If it still does not deliver the agreed service after that, you can cancel without any further deadline. How to end the contract cleanly and plan the switch is covered in Cancelling your internet.

If you cannot agree, the Schlichtungsstelle Telekommunikation (telecoms dispute resolution body) is the next step. The procedure is free for both sides, but you must have tried to reach an agreement with your provider first. In 2025 a procedure took around 14 weeks on average. As of 8 November 2026, the body is processing applications from about 46 weeks ago. Cancelling and switching is faster if another provider is available at your address.