A house flipping calculator is only as useful as the assumptions behind it. This guide shows how to estimate after repair value, renovation costs, financing, holding costs, selling expenses, profit, and maximum allowable offer so you can compare deals with a repeatable worksheet instead of relying on a purchase price that simply feels attractive.
Overview
A flip house profit calculator should answer two related questions: What might the project earn, and what is the most you can pay while preserving your required margin? The calculation begins with a realistic after repair value (ARV), then subtracts every cost required to acquire, renovate, finance, hold, and sell the property.
A basic project profit formula is:
Estimated profit = ARV − acquisition costs − renovation costs − financing costs − holding costs − selling costs
For an offer decision, calculate the maximum allowable offer (MAO) by working backward:
MAO = ARV − all costs other than the purchase price − desired profit
This approach is more reliable than using a broad rule of thumb alone. The 70 percent rule is often expressed as MAO = ARV × 70% − estimated repairs, but it is not a universal underwriting standard. It may not reflect local selling costs, financing terms, project duration, taxes, insurance, market liquidity, or the profit required for a particular risk level. Use it as a screening shortcut, then replace it with a complete deal analysis.
For a deeper worksheet-style starting point, see the house flipping calculator for maximum allowable offer and profit.
How to estimate
1. Estimate the after repair value
ARV is the estimated market value of the completed property, not the amount you hope to receive. Build it from comparable sales that resemble the finished project in location, property type, size, bedroom and bathroom count, condition, and buyer appeal.
Start with several relevant sold properties when available, then adjust your judgment for meaningful differences. A newly renovated home should not automatically be compared with a partially updated property. Likewise, a high-end finish package may not produce its expected value in a neighborhood where buyers prefer practical, mid-market improvements.
Document the address, sale date, size, condition, notable features, and reason each comparable supports your estimate. If the comps point to a range, use a conservative value for the first analysis rather than the highest possible outcome. The after repair value guide provides a more detailed comps framework.
2. Build the renovation estimate
Separate the renovation into visible work, required systems, exterior work, and contingency. Typical line items may include demolition, framing, roofing, electrical, plumbing, HVAC, windows, insulation, drywall, flooring, paint, cabinets, countertops, appliances, fixtures, landscaping, cleaning, and final punch-list work.
Use contractor bids, measurements, supplier quotes, and a room-by-room scope instead of a single rounded allowance. Include permit fees and inspection-related costs where applicable; the guide to permit costs for house flips can help identify items that are easy to omit. A room-by-room rehab cost estimator is also useful for organizing early assumptions.
Add a contingency as a separate line. Its purpose is to absorb uncertain conditions such as hidden water damage, outdated wiring, structural repairs, or material substitutions. Do not use contingency as permission to leave the scope vague. A clearer scope makes both bids and later changes easier to control.
3. Add financing and holding costs
Financing costs can include origination charges, lender points, interest, draw fees, appraisal or inspection charges, and other loan-specific expenses. Calculate interest based on the expected balance and the period the funds will be outstanding. If the lender finances only part of the purchase or renovation, include the cash you must contribute in your capital plan even though it may not appear as a loan expense.
Holding costs are the recurring expenses of owning the property during construction and resale. Common examples include property taxes, insurance, utilities, lawn or snow care, security, loan payments, association dues, and maintenance. Estimate them monthly, then multiply by a realistic timeline. A project that takes four months to renovate may require additional months for listing, contract negotiation, inspections, financing, and closing.
For a practical review of overlooked expenses, use the house flipping costs breakdown. Keep financing assumptions separate from operating assumptions so you can quickly test another loan structure.
4. Estimate selling costs
Selling costs can include brokerage compensation, seller-paid closing charges, transfer taxes where applicable, staging, photography, marketing, repairs requested during negotiations, and concessions. The actual items vary by transaction and location, so enter the assumptions you expect rather than applying a vague percentage without checking what it includes.
Staging and presentation should be treated as planned resale expenses, not last-minute extras. The goal is not to over-improve the property, but to present a finished home that matches buyer expectations for the neighborhood. Review the guidance on renovations for resale, as well as the separate articles on kitchen remodel ROI and bathroom remodel ROI.
Inputs and assumptions
Use the following worksheet for each property. Record the source or reasoning behind every number, then create low, base, and high cases.
- Estimated ARV: the conservative value supported by comparable sales.
- Purchase price: the proposed contract or offer amount.
- Acquisition costs: due diligence, inspections, legal work, lender fees paid at closing, title charges, and other purchase expenses.
- Rehab costs: the itemized scope of work, materials, labor, permits, disposal, and contingency.
- Financing costs: interest, points, origination, draw fees, and other charges.
- Monthly holding costs: taxes, insurance, utilities, maintenance, association dues, and debt service.
- Project duration: acquisition through renovation, listing, contract, and closing.
- Selling costs: marketing, staging, brokerage, seller-paid charges, concessions, and expected closing expenses.
- Desired profit: the minimum compensation required for the capital, time, uncertainty, and execution risk.
Then calculate:
Total non-purchase costs = acquisition costs + rehab costs + financing costs + holding costs + selling costs
Estimated profit at a given offer = ARV − purchase price − total non-purchase costs
MAO = ARV − total non-purchase costs − desired profit
Do not double-count costs. For example, if loan interest is included in financing costs, it should not also be included in monthly holding costs. Similarly, confirm whether a contractor estimate includes permits, disposal, appliances, and final cleaning before adding separate allowances.
Worked examples
Assume a property has a conservative ARV of $300,000. The estimated costs other than the purchase price are:
- Renovation and contingency: $55,000
- Acquisition costs: $6,000
- Financing costs: $15,000
- Holding costs: $12,000
- Selling costs: $24,000
Total non-purchase costs are $112,000. If the desired profit is $40,000, the maximum allowable offer is:
$300,000 − $112,000 − $40,000 = $148,000
At a purchase price of $148,000, the estimated profit is $40,000 before any costs not included in the worksheet. If the seller requires $160,000, the projected profit falls to $28,000 unless another assumption improves.
Now test the 70 percent rule as a screening comparison:
$300,000 × 70% − $55,000 = $155,000
The rule produces a higher offer than the detailed MAO because it does not explicitly account for the acquisition, financing, holding, and selling assumptions listed above. This difference is exactly why a complete calculator should control the final decision.
Run a downside case as well. If ARV falls to $285,000 and the project takes two additional months, both sale proceeds and holding costs change. A deal that works only at the highest ARV and shortest timeline has little room for ordinary execution problems. If the analysis shows a thin margin, consider lowering the offer, reducing the scope, improving the financing, or passing on the property.
When to recalculate
Revisit the calculator whenever a material assumption changes. Before closing, update the model with verified contractor bids, lender terms, inspection findings, and a revised ARV. During construction, recalculate after approved change orders, hidden-condition discoveries, material price changes, or schedule delays. Before listing, update selling costs, expected time on market, and any work still required for completion.
Recalculate after a change in financing terms, including interest rate, points, loan balance, draw timing, or extension fees. Also revisit the model when comparable sales shift, the finished design changes, or the local buyer pool appears less receptive to the planned price point.
For practical use, save one worksheet for the original offer, one for the approved project budget, and one for the final resale forecast. Date each version and note which assumptions changed. This creates an audit trail that helps explain why projected profit moved and improves future estimates.
Before making an offer, complete this short final check:
- Confirm the ARV with relevant, condition-matched comps.
- Verify the renovation scope and identify exclusions.
- Add contingency and realistic permit and inspection allowances.
- Calculate financing and holding costs through closing, not just construction.
- Include every expected selling expense.
- Test conservative ARV, higher costs, and a longer timeline.
- Compare the detailed MAO with the 70 percent rule, but do not let the shortcut replace the full analysis.
- Proceed only if the downside case still fits your risk and capital plan.
A calculator cannot remove uncertainty from house flipping, but it can make uncertainty visible. Updating the worksheet as facts improve turns a one-time estimate into a practical project-control tool.
