With these numbers, your maximum offer should be $87K.If these are the numbers, I will start my offer to the bank at $70K.If the days on the market is longer than 90 days, you need to use an even more conservative formula.

I use a commercial landlord policy for all my homes, and my agent provided me the formula they use based on the square footage for insuring my homes.

Here's my formula when evaluating a potential rental property:  Take your weekly rate and multiply it by 26. 

That being the case . 70% of $610,000 with no improvements and rent breaks even = $427,000 and you still have a $21,000 assessment.Current return on my money is 5.5% average.With Yields6% yield I have to spend $60,000 which yields tax free $19,000 and offer $316,000 + $21,000 assessment fee = $337,0007% yield and I have to spend $60,000 yields $19,000 = $271,142 +$21,000 assessment fee = $292,142Bigger Pockets formula for flipping and investment propety using ARV valueIf no improvements 70% of ARV assume comp value of $610,000 = $427,000 + $21,000 = $448,000 and no rental yield but the property is worth about $610,000.

One formula I've seen from different sources, Like Larry Goins and Vena Jones Cox for wholesale deals works like this:ARV (after repaired value, lowest in range)X 65% ( I have seen this range between 60-70%)- repairs (highest number in the range)= top offerThis is the formula used when buying rehabs from private owners.

We went to the "Flipping Formula" seminar and it made great sense to us, so we signed up for the 3 day bootcamp this weekend.

You'll learn the formulas quickly and will (hopefully) spend more time finding deals than agonizing over formulae.

I was really looking for a formula to help calculate what I should expect as far as large long-term repair expenses for example roof air-conditioning unit furnace etc.

Rich Dad Poor DadRich Dads Cash Flow QuadrantRich Dads Increase your financial IQThe Real Book of Real EstateThe ABC’s of RE InvestingThe ABC’s of PMRich Dad RE Tax AdvantagesThe E-MythThe 4 Hour Work Weekhttp://flip2freedomacademy.com - free e-bookFlip2freedom episode 77[http://www.flip2freedom.com/a-3-step-formula-to-a-successful-balanced-and-insanely-profitable-2012/] - podcast - LISTEN TO THIS TODAY!

But if you really wanted to come up with a more granular way of estimating that stuff, that would be the formula I'd look to put together.However, as I said, I'm too lazy for that to be honest.