Ok, if 750 Karma is assumed to be the official equivalent for 400 BP, how much Karma would be the official equivalent for 500 BP ? Pure matemathical equivalence would yield 937.5 Karma, so I was thinking to round it up to 950 for the sake of simplicity erring on the side of the player.

Are you playing with the x3 or the x5 cost multipliers for attributes? This can make a big difference.

I tend to assume that 750 karma/400 BP is an adequate equivalence if one uses the x3 cost multiplier for attributes. If one uses x5, the karma/BP amount IMO definitely ought to be increased, although I'm unsure how much, so I tend not to use x5. If one can suggest me an adequate increase, I can use x5, too. As a general rule, I prefer characters to be balanced but definitely powerful, elite runners and such. Using x5 with 750 karma/400 BP does not leave enough leeway IMO.

400 BP / 750 karma is roughly equivalent when you use x5, Karma builds still usually come out to a little more than 400 BP when converted. With attribute cost x3 750 Karma is much stronger than 400 BP.

@OP: I'd go with 900 Karma at the most (assuming you're using the errata rules with attriibutes x5). I'm playing a magician in a group that build their characters with 900 Karma and we're all real powerhouses in our speciality and still very broadly skilled in other areas without a lot of weaknesses. I think going even higher than that means you basically don't have to make that many decisions anymore because you can just take everyhing.

Seconded. Heck, if you're using 3x stats, 750 karma is almost equivalent to 500BP depending on the exact character type.

Interestingly though, karma is better with low cost characters, and a little worse with high cost characters. That's because the way things are set up, you get your best BP:karma ratio when you're maxing or near maxing stuff like you would in a 500 BP game.

I suppose one question though is: are you asking because you want to do a high powered karmagen or because you want to use it in conjunction with 500 BP characters? If it is the former, it isn't a big deal what exact number you use. If it is the later, I'd say 900 absolute max, maybe less. Try making a couple characters in each system and then converting them and see how close the numbers come.

Except that BP also gives you free knowledge skills, which Karma gen does not.

Not having to pay for your race though does make some intriguing balances.

Still, I've built some characters in BP and then translated them to the karma gen cost.
Most well made BP charactesr are actually worth 850+ in karma.

It really depends on the race, and what stats you buy.
If you have a couple of 6's and a couple of 1's then your Karma equivalency is much higher, than a more balanced character.

I've done alot of work on this, and found that, even including knowledge skills, you will generally be fairly even unless you're doing alot of min/maxing (Soft max a stat or leave it at 1. Get a skill at 4 or don't get the skill, etc)

I don't remember the exact numbers any more, but using 5x attributes and race costs karma equal to BP cost, and leaving qualities neutral on cost, I could make a 750 Karma character cost 750 BP, and I could make a 400 BP character cost somewhere around 1200 karma.

The karma character was a bit unplayable, but could easily be made playable and keep the cost over 700 BP in conversion.

The BP character was entirely playable, and actually fairly powerful.