Before you start

Completed Anmeldung (the 6-month clock runs from when you take up ordinary residence, which registration evidences)
Your original, valid foreign driving licence
Knowing your country's Anlage 11 category (full exemption, partial, or full tests)

Step-by-step

1
Check whether you even need to convert
EU/EEA licences stay valid in Germany until they expire — no action needed for most newcomers. Only non-EU/EEA holders must do the Umschreibung, and only they face the 6-month deadline.
OnlineWho: You—Free to check
2
Find your country's category in Anlage 11
Anlage 11 of the Fahrerlaubnis-Verordnung lists, per country (and sometimes per US/Canadian state), whether you are fully exempt from tests, need only the theory or only the practical, or must pass both. Listed states like the UK and many US states are commonly exempt; unlisted countries require both exams.
OnlineWho: You—Free to check
3
Gather documents, eye test and (if needed) first-aid course
You will need a biometric photo, an eye test, and — for non-exempt countries — a certified German translation of your licence and a first-aid course certificate. A driving school can confirm exactly what your category requires.
In personWho: YouEye test minutes; first-aid course ~9 hoursEye test <€10; first-aid ~€70; translation ~€60
4
Apply at the Berlin Führerscheinstelle and (if required) sit the exams
Submit your application and documents to the Berlin driving-licence authority. If your country is exempt you simply wait for the new licence; otherwise you book and pass the theory and/or practical test first. Berlin verifies foreign licences with the issuing authority, and that verification is the slow part — ask the Führerscheinstelle for a current estimate rather than planning on a figure from a forum.
In personWho: YouSeveral months; ask the Führerscheinstelle for current times≈ €37.50 issuing fee (plus exam/lesson fees if required)

Documents you’ll need

Original valid foreign licence + a photocopy
Passport or ID card
Registration certificate (Anmeldebestätigung)
Biometric photo
Eye-test certificate
Certified German translation of the licence or an International Driving Permit (non-exempt countries)
First-aid course certificate (non-exempt countries)

Things most newcomers don’t know

The 6-month clock runs from taking up residence, not from your Anmeldung.

§29 FeV gives a non-EU licence six months from the point you establish an ordinary residence (ordentlicher Wohnsitz) in Germany — not from the day you happen to register. Delaying the Anmeldung does not buy you extra time, and after the six months, driving on the foreign licence risks fines and voided insurance. The authority can extend the window by up to six further months only if you show you will not be resident beyond twelve. EU/EEA holders have no such deadline.

Source: §29 Fahrerlaubnis-Verordnung (gesetze-im-internet.de)

Your country — and sometimes your US/Canadian state — decides everything.

Anlage 11 treats licences case by case: some are a straight swap, some need only the practical, some need both exams. Two people from different countries face wildly different processes, so never rely on a friend's experience.

Source: Anlage 11 FeV (gesetze-im-internet.de)

Whatever you drive, the inside of the S-Bahn Ring is an Umweltzone.

Berlin's low emission zone covers the whole 88 km² inside the inner S-Bahn Ring — not just Mitte — and since 1 January 2010 only vehicles carrying a green Umweltplakette may enter it. The badge costs a few euros from a testing station, garage or the registration office, is bought once for the life of the vehicle, and is valid in every other German Umweltzone too. Buying a car that cannot qualify for a green badge makes most of inner Berlin unreachable.

Source: Senatsverwaltung für Umwelt — Berliner Umweltzone

Convert before the six months are up, even if you barely drive.

Once the window closes you legally need a full German licence to drive at all; there is no informal grace period, and an expired-validity foreign licence will not satisfy insurers after an accident.

Source: community-reported, verify

Common mistakes to avoid

Assuming a late Anmeldung restarts the six months — the clock runs from taking up residence
Assuming all US licences are exempt — it depends on the specific state in Anlage 11
Forgetting the first-aid course and eye test, which non-exempt applicants always need
Driving inside the S-Bahn Ring without a green Umweltplakette on the windscreen

Some of this may be out of date. Spotted something inaccurate? Help us keep it right for the next newcomer.