Bad Beat Jackpots

I normaly play in red chip games that do not have Bad beat jackpots.Sometimes I look at the Jackpots above 10grand that look tempting.For you guys[&girls]that are good at math:How high should the jackpot be when it's offering me an over lay? They normaly take $one dollar a hand.Requirements for O/8 are:4-10's...H.E.are:Aces full of 10's.. You must use both cards in your hand. Thanks H.N.