These are the plans for increased capacity on the various lines.
I'm looking at the Lewisham figures and the suggestion is that replacing the 3-car train every 4 minutes service between Lewisham and Bank and the 2-car train every 8 minutes service between Lewisham and Stratford with the new 5-car train every 4 minutes between Lewisham and Bank and the new 5-car train every *4* minutes between Lewisham and Stratford would increase capacity by 65%. As I understand it, the new 5-car trains offer 10% additional capacity to a current 3-car train so my maths makes that a 55% increase - still impressive but someone (probably me!) has their sums wrong somewhere.
The other question that occurs to me is whether a train every 2 minutes in and out of Lewisham station is achievable given how long a train would block the scissors crossover as it slowly approaches the buffers there.
A new 5 car train is a 65% increase in capacity itself over a 2-unit train at present, but if theres extra trains being run as well then its not just the additional capacity on the existing trains but the total capacity of extra trains running the extra services.
Per hour at the moment you have 60 units running through, in the future you will have 30 new trains. Each new train is worth 3.3 x the capacity of a single unit. So, in the future, you will have the equivalent of 99 units per hour; that is 165% of what runs now. So, theres your 65% boost.