I calculate mine by hand, because I've noticed that a lot of my monthly payment amounts listed in my credit reports aren't really accurate, some aren't listed at all, and some are listed accurately but aren't relevant.
For example:
I have some accounts where my monthly payment may have been hundreds of dollars last month, but this month they're $0 or $30.
My apartment rental is also reported in my credit report - which is largely irrelevant because most or all credit applications exclude housing costs listed in the report, and use the "monthly housing cost" field from the application instead (they might compare the two amounts to make sure they match, but they certainly don't add them together in my experience, otherwise my DTI would be 78% and I'd never get approved for anything). In the case of a mortgage app, apartment rent isn't even a factor whatsoever since the mortgage monthly payment would replace it.
My DTI is 28% excluding rent, or 52% including rent. Those numbers aren't great, but it's caused by my 2 car payments and a LOC payment that are $1,800/mo altogether. One car loan and the LOC will both be paid off in less than 18 months, after which my DTI will only be 11% excluding rent, or 35% including rent.
This means that, for me, if I had to stay under 43% DTI to qualify for an FHA mortgage (after my LOC and 1st car loan are finished next year), my mortgage payment would have to be $2,300 or less, which incedently put me right on par with my target home shopping price of $350k 
Total Loan Balance: $43k / $65k
Total SL: $78k
Interesting about rent. I assume it would be considered as a mtg loan pymt would be. But I've not paid rent in decades so not sure. But what you state makes sense when it comes to MTG apps. Wonder if it applies if DTI is a factor for non MTG apps...
@Trudy wrote:Interesting about rent. I assume it would be considered as a mtg loan pymt would be. But I've not paid rent in decades so not sure. But what you state makes since when it comes to MTG apps. Wonder if it applies if DTI is a factor for non MTG apps...
rent always factors into DTI, the same as a monthly mortgage payment does... the only question is where does the creditor get the rent/mortgage payment amount from? They either get it from the credit report, or they get it from the application where you declared it (or in the case of a mortgage app, they get it from a calculator), my only point was that they won't add the two together if it was both listed on the app and shown in your credit report. So if you rent, it might mess with the DTI calculations that a lot of credit websites use, because it could basically be including your rent payments once, twice, or not at all, depending on whether your rent is reported on your credit reports and whether or not you input it manually. I think a lot of people who don't realize this could be seeing a DTI that is either much higher or much lower than the reality.
Can't speak for any other underwriting, but for a mortgage it will go off what is listed on the credit report.
Rent is typically excluded from the calculation given the expectation once buying a house for most people (non-investment mortgage at least) is that you're going to kick that rent payment to the curb.
@Anonymous wrote:Turbo by intuit does, but you input your income yourself.
I have this app as well, however, it has doubled my mortgage payment (obviously a glitch) and try as I might to change it, it won’t correct. It has exponentially screwed up my dti, so, it’s rather useless for me. I’ve had to do the math myself to get a more accurate account.
