Most beginners spend their time on the purchase price and the renovation budget, then enter a single rough number for holding costs. Yet holding costs are the part of a flip that grows with every week of delay, and delays are common. This guide shows how to build a monthly carrying-cost figure, how to turn it into the holding-cost number the calculator asks for, and how much a slow project can cost. All numbers are illustrations.
Holding costs are what it costs to own the property while it produces no income. Typical items include property taxes for the period you own it, insurance (a vacant or under-renovation property often needs a different policy than an occupied home, so ask your insurer), utilities that stay on for contractors, loan interest and fees if you borrow, HOA dues if any, lawn or snow care, and security or cleaning. Costs that occur once, such as the purchase closing costs, are better entered with the purchase or sale numbers, depending on how you track them.
Assume you buy for $165,000 and borrow $140,000 on an interest-only short-term loan at an assumed rate of 11 percent (an illustration only; your rate and fees will differ, and the calculator does not model loans, so you add interest yourself). The monthly carrying costs might be:
| Property taxes | $250 |
| Insurance | $120 |
| Utilities | $180 |
| Loan interest ($140,000 x 11% / 12) | $1,283 |
| Total per month | $1,833 |
Notice that interest is more than two thirds of the monthly total. Financing is usually the largest holding cost when you borrow, which is why the loan terms deserve as much attention as the repair budget.
Count the whole period from closing on the purchase to closing on the sale: renovation time, any permit or inspection waits, the time on the market, and the weeks between a signed contract and closing. Many beginners count only the construction. Suppose you plan four months and a delay stretches it to seven. Holding costs become:
| 4 months x $1,833 | $7,333 |
| 7 months x $1,833 | $12,833 |
| Difference | $5,500 |
Using the calculator's other default inputs (ARV $280,000, repairs $35,000, purchase $165,000, selling costs $16,800), the estimated profit moves like this:
| Scenario | Total cost | Estimated profit |
|---|---|---|
| Four-month project | $224,133 | $55,867 |
| Seven-month project | $229,633 | $50,367 |
Three extra months cost $5,500, about ten percent of the profit, and nothing was wrong with the renovation itself.
Time also exposes you to the market. If the finished house sells 5 percent below your ARV, at $266,000, and you pay 6 percent selling costs on the lower price ($15,960), the seven-month project from above has a total cost of $165,000 + $35,000 + $12,833 + $15,960 = $228,793 and a profit of $37,207. A pair of ordinary setbacks has turned a $55,867 plan into a $37,207 result. Try your own downside case in the calculator before you commit: lower ARV, higher repairs, longer timeline. If the deal only works when nothing goes wrong, it is a fragile deal.
Besides the monthly carry, buying and selling involve one-time costs: title, recording and transfer taxes or fees, lender charges, and agent commissions. These vary widely by state, county and deal, so use ranges and your own quotes rather than a universal percentage. For financed purchases, the lender must give you a Closing Disclosure at least three business days before closing (CFPB), which lists the closing costs, a useful check on your estimate. For the sale side, ask your agent and title company for an estimate of what you will pay.
Use a simple worksheet like this one, with your own figures, and enter the monthly total times the number of months in the holding-costs field:
| Item | Where the number comes from |
|---|---|
| Property taxes | Tax bill or county records, divided by 12 |
| Insurance | Quote for a vacant or renovation-stage policy |
| Utilities | Past bills or the utility's estimate, during construction |
| Loan interest and fees | Your lender's term sheet or loan estimate |
| HOA dues | HOA statement, if any |
| Lawn, snow and cleaning | Local quotes |
| Reserve for surprises | A percentage you choose and document |
Revisit the worksheet every month during the project. If the actual monthly total runs above your plan, update the calculator and see what it does to your profit while you still have time to react.
Enter the total of the months you expect (and then a slower case) in the holding-costs field, add financing interest and fees yourself, and compare the result. The comparison tells you how sensitive your deal is to time, and that sensitivity is a better guide to risk than any single profit figure.
Run your own numbers in the calculator, read The 70% Rule Explained, or see the methodology. Guides: estimating ARV and repairs, how flip profits are taxed, holding costs and timeline.