Cheapest way to commute from Gravesend to London Bridge via public transport

That's a fairly complicated question. "Cheapest" would probably be biking, but this may not be acceptable to you (although it is to some people).

If you look at train tickets, there are indeed a large number of options and "cheapest" depends on you exact details and preferences.

Factors that impact the prices are

1. Can you travel off-peak? Before 7am or slight after 9am?
2. Do you want to use high speed rail ?
3. Do you want just the commute or general London travel include ?

You also have to be pretty precise of what your commute schedule will be. 3 times a week is VERY different from 5 times per week. Do you do work travel (being gone for a week at a time)? do you typically take off a month or so in summer?

The best way to go about this is to make a spreadsheet of all the different options and rate them according to your preferences and cost them out based on your anticipated usage pattern. Yes, that's a couple of hours of work but you are looking at maybe £4000 per year, so this may be a good investment of your time,

Major options are

1. Thameslink
2. National Railway

Thameslink pricing for no high speed, no London, peak hours (most flexible) is

• Daily: £28.40
• Weekly: £97.80 or 3.4 days
• Monthly: £375.60 or 3.8 weeks or 13.2 days
• Yearly: £3912.00 or 10.4 months, 40 weeks, 138 days

The also have an interesting option of a Flex ticket, which is 8 day passes for roughly £25 each to be used with 28 days. That can be interesting if you do 3 or less days a week.

I think I was able to make a 16-25 railcard work using this link: https://www.traintickets.com/search/?/results/155081/153623?departdate=2022-03-15T07:30:00&railcards=YNG%7C1&returndate=2022-03-15T17:00:00

This brought the daily down to £18.70 which could be a substantial savings. You may want to call up Thameslink to check whether the 16-25 railcard can be applied to their season tickets as well.

Update based on the cycling discussion

If you stick with railcard augmented anytime day tickets, you can mix and match to you heart's content. The railcard itself is only £30 (I think)

1. Gravesend to London is £18.70
2. Dartford to London is $12.70
3. Dartford is the first stop in London Zone 6, so if you want to do a bunch of outings in London as well you can pay London 1-6 anytime day pass for £14.10 instead

So if you are feeling active and the weather is nice, you can bike to Dartford and then take the train from there and if not, take the train from Gravesend. Try that for a while and see how it goes.

If the season tickets can't be used with the railcard, than the railcars is probably the winner. The season tickets are only a winner if you are a very regular commuter, which these days is not that common anymore.

I the comments there's discussion of cycling. I ride a lot, and I'd do that journey sometimes, but not every day. But that does lead to a possibility.

However, if you're prepare to ride as far as Crayford (about an hour's ride), a day return drops from £28.40 to £16. Dartford comes in at £19.30, and is about 15 bike minutes closer to Gravesend. Compared to a longer ride, this should also be less sweaty. There should be a toilet on the train where you can get changed - I've often done this on my bike+train commute.

Both have bike parking, apparently with shelters. You'd need a good lock and to remove lights, etc., but I've done something similar daily in Bristol for the last few years.

There should be flex and railcard options comparable to the ones in Hilmar's answer from these stations as well, but in general in London, if you can start a zone or two closer, you can save quite a lot.