How do you calculate pre-flop starting hand percentages?

For example, when I see pocket 2s vs AK, it's 51% vs 49%.

When it's Pocket Kings vs A 3, then it's 65% vs 35%

How do they come up with these values? I just seemed to have them memorized but never know where it's coming from.

For example
low pocket pair vs two overcards (pocket 77s vs AK) is 52 vs 48 more of a coin flip

middle pocket pair vs one high card and one low card (pocket 7s vs A 3) is 66 vs 33 or 2:1 favorite

high pocket pair vs low pocket pair is(AA vs KK) is 80 vs 20 or 4:1 favorite

dominated card such as (AK vs AQ) is 75% vs 25% or 3:1 favorite

How do they calculate these?

Can anybody answer?

Preflop;

Start with any random 2 cards. Based on the showdown value of those 2 cards AGAINST THE REMAINING PLAYERS, the odds can be derived. So your 23 offsuit will lose to every other hand in a PF showdown. There is an absolute linear correlation when only considering those 2 PF cards. So your 2 cards will fall on that linear chart somewhere. And based on probabilities of improving your original 2 cards, recalculated odds can alter your standing on that 2 card linear chart. So 87 suited is higher on that chart than 87 offsuit.

Extrapolate for the flop, turn, river, but not for the showdown because at that point there are no more odds of winning, there is only the truth.

I'm not familiar with any calculator enough to state whether or not they take into consideration how big the original table is. 10,9,8 6 seats etc. But any calculator would work if it knows how many hands are left to act.

very interesting DJ11. i haven't gotten that far, but i'm a little familiar with it.
guess i'll check out pokerstove too. thanks guys.