ThameslinkorTrain to Brighton?

The short answer

These do not go to the same place, so price is not the comparison. The Thameslink reaches Victoria, with London Bridge and the City on Thameslink; the Train to Brighton does not. Brighton is a separate city on the south coast, not part of London.

The Thameslink is quicker: 29 min against 30 min. The Train to Brighton varies between 26 and 38 minutes.

Thameslink: Runs all night. Train to Brighton: 04:58–01:58.

Priced against each other

Whole-party totals · adult fares

What each costs for the whole party, in GBP. The cheaper of the two is marked on every row.
Travelers	Thameslink	Train to Brighton	Difference
1	£10.70	£13.70	£3
2	£21.40	£27.40	£6
3	£32.10	£41.10	£9
4	£42.80	£54.80	£12
5	£53.50	£68.50	£15
6	£64.20	£82.20	£18
7	£74.90	£95.90	£21
8	£85.60	£109.60	£24

Side by side

Where each one leaves you

Thameslink · ThameslinkThameslink

From: Gatwick Airport station, in the South Terminal
To: London Bridge, then Blackfriars, City Thameslink, Farringdon and St Pancras International
Luggage: Racks by the doors and overhead.
Runs: All night
Journey: 29–63 min

Overnight it is hourly and skips London Bridge: from the airport 00:02, 00:42, 01:45, 02:45, 03:45 and 04:20 on weekdays, about 50 minutes to Blackfriars and an hour to St Pancras.

By day it takes 29 minutes to London Bridge and about 44 to St Pancras; some trains stop more and take up to an hour.

Tapping is the cheap way off-peak and the dear way from 06:30 to 09:30 on weekdays, when the £14.40 paper ticket saves £4.80.

Thameslink: price for every party size

Check times and fares with National Rail

regional · Southern, Thameslink and Gatwick ExpressTrain to Brighton

From: Gatwick Airport station, in the South Terminal
To: Brighton station, direct
Runs: 04:58–01:58
Journey: 26–38 min

Buy a ticket before the barrier: a tap in at the airport does not cover a journey south to Brighton.

Train to Brighton: price for every party size

Check times and fares with National Rail

This compares two of 9 options. See all of them ranked for your party size

ThameslinkorTrain to Brighton?

Priced against each other

Side by side

The other comparisons at Gatwick