House Flipping Calculator
NYC flips carry a cost most national flip calculators ignore: this city’s mansion tax, mortgage recording tax, and transfer taxes are some of the highest in the country, and they hit a flip twice — once as a buyer on the way in, once as a seller on the way out. This calculator runs your numbers through the real NYC rate schedules on both sides of the deal, plus the 70% rule, holding costs, and ROI on your actual cash invested.
What Is the 70% Rule?
The 70% rule says don’t pay more than 70% of the after-repair value (ARV) minus your rehab budget. The formula is Max Offer = (ARV × 0.70) − Rehab Costs. The 30% gap is meant to cover your financing costs, holding costs, selling costs, and profit — in a high-tax market like NYC, that gap gets eaten into faster than the rule of thumb assumes, which is exactly why itemizing the real numbers matters more here than in most markets.
Results
Enter a purchase price and an after-repair value below to see your numbers.
Common Questions
Pull recently sold comps within the same neighborhood, similar square footage and unit mix, that have already been renovated to the finish level you’re planning. ARV is what a comparable finished property actually sold for, not a guess at what you’d like to get — a real estate agent pulling live comps is more reliable than an automated estimate.
Mansion tax, mortgage recording tax, and title insurance are all buyer-side costs — you owe them on your purchase regardless of whether you plan to live there or resell it. On the sale side, you owe NYC and NYS transfer tax instead, which is a seller obligation. A flip effectively touches both sets of taxes, once on the way in and once on the way out.
Most flips are financed with short-term hard money or bridge loans, priced higher than a 30-year owner-occupied mortgage and typically structured as interest-only during the hold, since you’re not trying to build equity — you’re trying to sell before the loan matures. This calculator assumes interest-only for that reason.
Many investors target 15-20%+ return on cash invested to justify the risk and effort of a flip; below 10% the risk-reward math gets hard to justify, especially once you account for the time value of your own labor managing the project. Your target should scale with how much risk the specific deal carries — a light cosmetic refresh justifies a lower margin than a gut renovation.
Treat it as a starting sanity check, not a hard rule. NYC’s unusually high transfer taxes and closing costs eat into the 30% buffer faster than in lower-cost markets, so run the full itemized numbers above rather than relying on the rule of thumb alone before making an offer.
It doesn’t include permit fees, architect or engineer costs, contractor overruns beyond your stated rehab budget, or capital gains tax on the profit — short-term flips are typically taxed as ordinary income, so talk to your accountant about your specific tax exposure before finalizing your numbers.
