ROI calculation for flips under 365 days

Looking for an Excel formula to calculate this ROI.
Example:
$90,000.00 purchase price (all expenses inclued) on 02/01/2013
$ 5,000.00 contractor draw #1 on 02/03/2013
$ 3,500.00 contractor draw #2 on 02/16/2013
$ 6,500.00 contractor draw #3 on 02/26/2013
$10,000.00 resale expenses and credits to Buyer
$115,000 total investment capital
$140,000 resale proceeds
$ 25,000 Gross profit on 06/15/2013

As you can see, there are approximately 120 days from start to finish in this investment cycle. I need the financial formula to calculate this ROI knowing 1) the length of time for each investment is variable, and 2) renovation and other expenses will be random in the equation.

The tutorials I have found calculate for an annual ROI. However, I want to calculate on shorter time periods and random expenditures. Is there such a forumula - or an investment program that calculates in this manner?

Resale expenses/credits? Are the actual out of pocket dollars? If so than yes deduct it. If they are figment reduction on sales price than they should already be calculated into your sales price.

25,000/115,000 is a 21.74% R.O.I.

In this type of investment there’s no need to worry about time. Profit / Costs = ROI

Yes, they are actual expenses (i.e. commissions, Seller paid closing costs, etc.).

I don’t think I was clear in my question. I am looking for a method to calculate the annual ROI on an amount of money - not each specific investment. The ROI calculation you provided is based on an annual ROI for each investment property, not the allocated money.

Example: $1,000,000 allocated to purchase and resell properties. If you factor the annual ROI for an investment property, then your ROI calculation is accurate. However, if the money is immediately reinvested into a new investment property that closes by the end of the same fiscal year, the ROI formula you provided is no longer an accurate indicator of ROI for the $1,000,000 allocated for investment purchases.

ROI is calculated as return/investment. To include annual return, include years in the denominator. 3 months is .25. So, it’s return/(investment*years)

You are over thinking it, trying to over analyze.
Profit/1,000,000

So in regards to this ROI I think is what you are looking for: 2.5%. And to put it into English: This property transaction contributed a 2.5% return on our original capital.

Again the ROI has nothing to do with a timeframe other than when you calculate your profit.

For instance if I had a property that I bought for 100k (let’s assume all cash), had an annual profit on the rent as 5k and sold it after the first year for a 20k Profit my roi would be 25%
5 years out 45%
15 years out 100%