Maximum Allowable Offer Calculator: How to Set a Safe Purchase Price on a Flip

Overview

If you flip houses long enough, you learn that many bad projects begin with a purchase price that looked manageable on paper but left no margin once real costs showed up. A maximum allowable offer, often shortened to MAO, is the ceiling price you should pay for a property based on your estimated after repair value, rehab scope, transaction costs, holding costs, and target profit.

In simple terms, MAO is not the price you want to pay. It is the highest price the deal can support.

This is why a maximum allowable offer calculator is useful. It turns deal underwriting into a repeatable process instead of a guess. You can use it to screen properties quickly, compare multiple deals, or stress-test a purchase before making an offer. It also gives you a common language when talking with lenders, partners, or agents.

Many investors first learn MAO through the 70 percent rule. That shortcut can be helpful for rough screening, but it is still a shortcut. Real deals often require a more detailed calculation, especially when rehab is heavy, financing is expensive, or your market has unusual resale costs. If you want the shorthand version, see 70 Percent Rule Calculator: How to Set Your Maximum Allowable Offer on a House Flip and The 70 Percent Rule Explained: When House Flippers Should Follow It and When to Adjust.

A more complete house flip purchase price calculation usually looks like this:

MAO = Expected resale price (ARV) - rehab costs - purchase closing costs - financing costs - holding costs - selling costs - desired profit - contingency

That formula is less catchy than a rule of thumb, but it is far more useful. It forces you to acknowledge the full cost stack of a flip. It also helps explain why two investors can reach very different maximum offers on the same property. One may have cheaper capital, better contractor pricing, or a lower profit target. Another may need more margin because the project is complex.

If you are still building your process, this article pairs well with How to Analyze a Fix and Flip Deal Step by Step and House Flipping Calculator Guide: How to Estimate Profit, Holding Costs, and ROI.

How to estimate

Here is a practical way to use a mao calculator without overcomplicating your first pass.

Step 1: Estimate the after repair value

Your ARV is the price you reasonably expect to sell for after the renovation is complete. This number should come from local comparable sales, not optimism. Compare homes with similar size, layout, finish level, lot type, and location. If your planned renovation would produce a clean mid-market resale, your comps should reflect that level of finish rather than luxury assumptions.

Be conservative. A weak ARV estimate can ruin the whole deal because every other number depends on it.

Step 2: Build a rehab budget from a real scope

Do not enter a single rough number like “$40,000 rehab” unless you have already broken it down. A strong MAO starts with a line-item scope of work: roofing, HVAC, electrical, plumbing, kitchen, baths, flooring, paint, permits, debris, landscaping, and punch list. If possible, price the work using contractor bids or your own historical cost data.

If you need help controlling this stage, read How to Find Contractors for House Flips: Vetting, Pricing, and Red Flags.

Step 3: Add purchase and financing costs

Many beginners subtract rehab from ARV and stop there. That is not enough. You also need to include closing costs at purchase, loan fees, interest, draws, insurance requirements, and any lender-specific charges. If you use hard money or private financing, these costs can materially affect the safe purchase price.

For a deeper comparison of funding structures, see Fix and Flip Loan Rates Guide: Hard Money vs Private Money vs HELOC.

Step 4: Estimate holding costs

Every extra month eats into profit. Include property taxes, insurance, utilities, lawn care, HOA dues if applicable, and any monthly loan payments or accrued interest. Also account for the likely timeline from closing to resale, not just the construction schedule. Many flips sit after the work is done because the market softens, staging takes longer, or buyer financing adds delays.

Step 5: Estimate selling costs

When you sell, the proceeds are not equal to the contract price. You may have agent commissions, seller-paid concessions, transfer taxes, title-related fees, staging, cleaning, photography, and touch-up work. Build these into the calculator rather than pretending they will be small enough to ignore.

Step 6: Set a target profit and contingency

Your desired profit should reflect the amount of capital, time, and risk involved. A cosmetic update on a straightforward property may justify a different margin than a structural rehab with permit exposure. A contingency is separate from profit. It is a buffer for unknowns such as hidden water damage, code upgrades, or a longer listing period.

Once all of those figures are in place, subtract them from ARV. The result is your maximum allowable offer.

Basic MAO formula

MAO = ARV - Rehab - Purchase Costs - Financing - Holding - Selling Costs - Profit - Contingency

If the resulting number is too low to win the deal, that does not mean your calculator is wrong. It may simply mean the deal does not fit your model.

Inputs and assumptions

The quality of a maximum allowable offer calculator depends on the quality of its inputs. Here is how to think about each one.

1. After repair value

ARV should come from a disciplined comps analysis. If nearby renovated homes are selling in a range, consider underwriting to the lower or middle end unless the property has a clear advantage. Avoid stretching ARV because the kitchen will look nice or because the listing agent suggested a stronger resale number.

Good ARV assumptions usually consider:

• Recent comparable closed sales rather than only active listings
• Similar square footage, bed and bath count, and lot characteristics
• Comparable renovation quality
• School district, street appeal, and micro-location differences
• Whether the resale market is stable, softening, or improving

2. Rehab costs

A reliable rehab cost estimator starts with scope control. Separate must-do items from optional upgrades. Focus on repairs and improvements that support your resale comp set. In many markets, over-improving a flip is just as damaging as underestimating repairs.

Common rehab categories include:

• Exterior repairs and paint
• Roofing and gutters
• Windows and doors
• Electrical, plumbing, and HVAC
• Kitchen and bathroom updates
• Flooring, drywall, trim, and interior paint
• Permit costs and inspections
• Trash-out, cleaning, landscaping, and staging prep

If you are deciding what to update, center your budget on resale impact, not personal taste. Practical items often matter more than flashy finishes. For related reading, see What Makes a Good House to Flip? A Screening Checklist for Buyers.

3. Financing costs

This line item varies widely by loan type. Hard money, private money, cash, and HELOC-backed deals all behave differently. Even if the purchase looks good, expensive capital can compress the margin enough to change your safe offer.

Your financing assumptions may include:

• Origination or lender points
• Interest expense over the projected hold period
• Appraisal, underwriting, wire, and legal fees
• Draw inspection fees
• Extension fees if the project runs long

When comparing lenders, calculate total carrying cost, not just the quoted rate.

4. Holding costs

Holding costs on a flip are easy to underestimate because they look small in monthly form. But six or eight months of taxes, utilities, insurance, and upkeep can meaningfully reduce profit. If the house is vacant, you may also face winterization, yard maintenance, or security costs.

5. Selling costs

A profitable exit depends on net sale proceeds, not gross price. Your calculator should include every cost that comes off the top at resale. If your market commonly requires seller concessions or closing cost assistance, include an allowance.

6. Profit target

This is the line many new flippers quietly reduce to make a deal work. That is risky. Profit is not leftover money; it is compensation for uncertainty, management time, market movement, and capital exposure. If your profit target disappears the moment one number shifts, the deal was probably thin to begin with.

7. Contingency

Always carry a contingency for rehab and, if appropriate, for timeline. Older homes often reveal surprises after demo. Even a solid contractor estimate can miss hidden issues. A conservative underwriting model assumes that some things will cost more or take longer than planned.

8. Timeline assumptions

Your flip timeline shapes both financing and holding costs. Underwrite the full cycle: acquisition, planning, permit wait time if needed, construction, punch list, photos, listing, contract period, and closing. A six-week rehab can still become a five-month hold.

If you are new to process control, House Flip Checklist: From Offer to Closing Day and Flipping a House for the First Time: Beginner Mistakes That Kill Profit can help you pressure-test your assumptions.

Worked examples

These examples use simple numbers to show the logic of a house flip purchase price calculation. They are illustrations, not market benchmarks.

Example 1: Cosmetic flip with moderate financing cost

Assume you estimate the following:

• ARV: $300,000
• Rehab: $45,000
• Purchase closing costs: $4,000
• Financing costs: $12,000
• Holding costs: $8,000
• Selling costs: $21,000
• Desired profit: $30,000
• Contingency: $10,000

MAO = 300,000 - 45,000 - 4,000 - 12,000 - 8,000 - 21,000 - 30,000 - 10,000 = $170,000

In this case, $170,000 is the maximum allowable offer. Offering more may still produce a profit, but it would reduce your buffer and move the project outside your target margin.

Example 2: Same property, ARV reduced

Now assume your comps review becomes more conservative and you adjust ARV from $300,000 to $285,000.

MAO = 285,000 - 45,000 - 4,000 - 12,000 - 8,000 - 21,000 - 30,000 - 10,000 = $155,000

A $15,000 drop in ARV reduced your safe offer by the same amount. This is why disciplined comps analysis matters so much in deal underwriting.

Example 3: Same property, rehab bid increases

Return ARV to $300,000, but your contractor estimate rises from $45,000 to $60,000.

MAO = 300,000 - 60,000 - 4,000 - 12,000 - 8,000 - 21,000 - 30,000 - 10,000 = $155,000

The result is identical to the prior example, but for a different reason. Either a weaker resale assumption or a larger rehab budget can force the same purchase adjustment.

Example 4: Fast screen using a rule of thumb

Some investors use a quick screening rule before running a full house flipping calculator. One simplified version is:

MAO = ARV x target percentage - rehab

If your target percentage is 70 percent and ARV is $300,000 with rehab at $45,000:

MAO = 300,000 x 0.70 - 45,000 = $165,000

This can be useful for triage, but notice how it differs from the detailed model. The gap may be small or large depending on your financing, hold period, and selling costs. Use shorthand formulas as filters, not final underwriting.

How to use these examples in real life

When you evaluate a deal, run at least three cases:

• Base case: your best realistic assumptions
• Conservative case: lower ARV, higher rehab, longer hold
• Optimistic case: only for comparison, not for deciding your offer

If the deal only works in the optimistic case, it is usually too thin. A safe MAO is one that survives ordinary friction.

When to recalculate

A maximum allowable offer is not a one-time number. It should be updated whenever the inputs that drive it move. This is the main reason a calculator-based approach is worth revisiting over time.

Recalculate your MAO when any of the following changes:

• Your ARV estimate changes. New comps, a softening market, or a revised resale strategy can alter your value assumption.
• Your rehab scope changes. Once you get contractor walk-throughs, permits, or inspection findings, the budget may expand or contract.
• Lending terms change. Different points, rates, draw schedules, or extension fees can lower the purchase price the deal supports.
• Your timeline changes. A longer construction or sale period increases holding and financing costs.
• Your exit plan changes. If you shift from a fast resale to a higher-finish retail listing, your costs and sales assumptions may both change.
• The seller counters at a higher number. Re-run the deal rather than forcing the numbers to fit the asking price.

For a broader discussion of market context and margins, see Is House Flipping Worth It in 2026? Profit Margins, Risks, and Market Realities.

A practical MAO checklist before you make an offer

• Confirm ARV with recent, relevant comparable sales
• Use a written scope of work instead of a rough rehab guess
• Include lender fees, interest, and realistic hold time
• Add taxes, insurance, utilities, maintenance, and resale costs
• Keep profit and contingency separate
• Run a conservative scenario before setting your ceiling
• Decide your walk-away number in advance

The final step is simple but important: write down your MAO, your preferred offer, and your absolute ceiling before negotiations begin. That protects you from making a decision based on competition, urgency, or seller pressure.

A good maximum allowable offer calculator does not just help you estimate a number. It helps you stay disciplined. In house flipping, discipline at acquisition often matters more than creativity during the renovation. Buy right, and you give the project room to work. Buy wrong, and even a strong rehab may not save it.