Total Loan Approval Amount/Online Calcs - Duplex, first home

[Matthew A.]

Hello Friends, 

Finally found a house in CT that me and my girlfriend want to put an offer on. My mortgage broker who was working with is basically gone for 4th of July so I figured I would ask a couple of questions here first. 

How accurate are online home loan calculators that decide how much you can afford? I used the FHA calc and it said around $270,000 max, but then I use smart assets, bankrate or some others and its SIGNIFICANTLY lower.. like, now we wouldn't qualify for the house asking $239,000 lower. Lower like... freaking telling me I qualify for $200,000?? huh?

We easily pay our $1,400 rent right now with flying colors and each save a grand, but I can't afford basically the same amount in a mortgage with taxes etc? Doesn't make sense to me. 

Are FHA debt/income higher than conventional loans, because it seems like that's the only one that gives us a much higher amount?

Also, will the other unit that will be rented after we buy count towards that? It would most likely put us far far in the clear if that's the case. 

Any help would be greatly appreciated!

PS $94,000 combined income on W2, $12,000 extra if rental income is allowed, $1,370 combined monthly debt (student loans, cars etc.. blahh) house is asking $239,000 we would probably do 5% down, P&I $1,052, Taxes are $380 a month, Insurance $170 a month, PMI I think is about $160.

Thanks Folks,

Matt