Paris to Hamburg by train

2 x optimum connections per day

Look at a rail map of Europe and it will look as though the logical routing for a journey by train from Paris to Hamburg would be via Koln/Cologne
However, thanks to the expansion of the high speed rail network, this alternative routing via Mannheim has comparable journey times.

This route via Mannhiem also tends to be cheaper than travelling via Koln/Cologne; DB (German national railways) makes its discounted Europa-Spezial tickets available on this route, but not on the route via Koln.

Plus you will also have around an hour between trains to make the transfer in Mannheim, so making the connection into the train on to Hamburg is virtually guaranteed.

The other alternative journey option via Karlsruhe is faster, but it is dependent on making on more tightly timed connection between trains,

A potential negative of taking this route via Mannheim, is that both of these optimum connections involve departing from Paris before 09:30.
Note that this routing departs from Paris Est and not from Paris Nord.

1 x connection per day

If you were looking at a European Rail Map, then Karlsruhe wouldn't be a seemingly logical location in which to change trains when making a Paris to Hamburg train journey.

Karlsruhe is somewhere south of the shortest straight line distance between the two cities - and one of the alternative routes sticks closer to that shortest distance.

However, thanks to the European high speed rail network, the fastest possible journey between Paris and Hamburg by train is usually to depart from the French capital at around 13:37 and change trains in Karlsruhe.

Though if you opt for this routing and the transfer time between trains at Karlsruhe will be around 26 mins; and it's that comparatively short connection between trains, which makes this the fastest journey overall.

So ideal IF the train from Paris arrives on time, but something of a gamble if the train happens to be late.
In that scenario, tickets can be transferred free of charge to a later departure, but the optimum connection will then involve making an additional change of trains at Frankfurt (Main).

Though you can remove the pressure of making that connection in Karlsruhe, by travelling via Mannheim (see above)

Note that this routing departs from Paris Est and not from Paris Nord.

This routing via Koln/Cologne is the shortest in terms of kilometres travelled, but to somewhat the surprise of ShowMeTheJourney, it's not the only option when taking a train from Paris to Hamburg.

It is quicker (and usually cheaper too) to head off from Gare de l'Est in Paris and to travel alternative routes via Mannheim or Karlsruhe,

Mon-Sat: 4 x optimum connections per day
Sunday: 3 x optimum connections

When making the journey from Paris to Hamburg by a combination of these Thalys and IC/ICE trains, two of these connections sold by B-Europe involve making connections in Dortmund.

However, the first connection of the day involves changing trains in Koln/Cologne, while the fastest connection of the day, on this route, actually involves making the transfer between trains at Dusseldorf Hbf.

(This is one of those scenarios that our unique software struggles to manage).

No matter where you will be making the connection between trains, the time to make the transfer will be around 45-55mins, so successfully connecting into the train on to Hamburg is virtually guaranteed.
This comparatively stress-free connection is the big plus for following this route.

In the very rare event of the Thalys from Paris being too late to make these connections, tickets can be transferred free of charge to a later departure.
Though not if you'll be making the final connection of the day which departs from Paris at around 15:55.

Reservations are optional on the train between Dortmund and Hamburg, but that is an exceptionally busy route, so opting to add them to a booking is highly recommended.