mtg when to mulligan

[later]

how do you know when to mulligan in magic

[Arix]

There is no hard and fast rule that tells you when you should. It all comes down to how your deck works and personal judgment. Generally, if you won't be able to do anything for the first three turns or so, you should mulligan.

It's a lot easier in our casual games because we allow free mulligans. Tournaments (and some casual circles) won't give you that luxury.

[Kappu1]

If you draw 7 cards and have 7 lands or 7 creature/spells then it's pry a good idea.

Really you need to know how your deck works to judge that.

[kip]

if i have less then 2 lands i mulligan or if i have less then 3 lands and bad cards i also mulligan if i have 3 lands or more i usually dont mulligan even if i have bad cards

[Logi]

If you draw 7 cards and have 7 lands or 7 creature/spells then it's pry a good idea.

Really you need to know how your deck works to judge that.

I think there's a rule that if you draw 7 cards with either no lands or all lands you can mulligan for free (ie you can draw 7 cards again instead of 6 cards from normal mulligan)

[Arix]

There used to be a rule like that. Not any more though.

[Aoe]

if i have less then 2 lands i mulligan or if i have less then 3 lands and bad cards i also mulligan if i have 3 lands or more i usually dont mulligan even if i have bad cards

That's a reasonable approach

[Urza]

There used to be a rule like that. Not any more though.

yeah see here:
no land mulligan mtg

The old and I mean OLD mulligan rule was that if you have no land or all land you could reveal this to you opponent and redraw 7 cards. You could only do this once so if you got another bad hand you were just out of luck.

In around 1996ish for the Paris event they tested a new rule of if you didn't like your hand for any reason you could just reshuffle and draw 1 less card. You could also repeat this process until you got to 0 cards.

For a while both mulligan rules were legal and you had to announce "I'm taking a standard mulligan." or "I'm taking a Paris mulligan." around 1998-ish the DCI adopted the "Paris mulligan" as the only rule for mulligans from then on and it remains so to this day.

So a really long answer to a short question, your method is just a house rule, but it has roots in original magic.