Let's cut through the noise. You've heard about the 70% rule in house flipping, probably from a podcast or a YouTube guru. It sounds simple, maybe even too simple. Buy a house for 70% of its fixed-up value minus repairs. How hard can it be? I've been flipping houses for over a decade, and I can tell you that's where most new investors trip up. They treat the 70% rule like a holy commandment, apply it blindly, and then wonder why their first deal barely broke even or, worse, lost money.

The 70% rule isn't a magic formula that guarantees profit. It's a risk management framework. Its real purpose is to force you to account for all the hidden costs and market uncertainties before you write a check. This guide will break down the rule, show you exactly how to use it (and when to break it), and share the subtle mistakes I see even seasoned flippers make.

What's Inside This Guide

What Exactly Is the 70% Rule?

At its core, the 70% rule is a quick math check for house flippers. It gives you the maximum price you should offer on a potential flip property. Here's the formula everyone quotes:

Maximum Allowable Offer (MAO) = (After Repair Value x 0.70) - Estimated Repair Costs

Let's unpack those terms because this is where the first misunderstanding happens.

  • After Repair Value (ARV): This is NOT your optimistic dream price. It's the realistic, current market value of the property after all your renovations are complete, based on recent sales of comparable homes (comps) in the same neighborhood. Not the Zestimate. Not what you "feel" it's worth. Solid comps.
  • Estimated Repair Costs: This is the total cost to get the property from its current condition to a market-ready state. It includes materials, labor, permits, and a contingency buffer (usually 10-20%) for the unexpected. That broken pipe behind the wall? That's what the contingency is for.

The "70%" part represents the portion of the ARV that is allocated to covering your purchase price, repair costs, and—this is critical—your profit, holding costs, and transaction fees. The remaining 30% is meant to be your safety net for all those other expenses.

Why You Absolutely Need This Rule (Even If You Think You Don't)

New investors often think, "I'll just buy low, fix it up nice, and sell high." Emotions take over. They fall in love with a property's potential or get scared of losing a deal in a hot market. The 70% rule acts as an emotional circuit breaker.

Its primary job is to protect you from yourself by baking in the costs you're most likely to forget:

Cost Category What It Includes Typical Range (as % of ARV)
Purchase & Repair Costs Your offer price + all renovation expenses. Covered by the 70% portion.
Holding Costs Loan interest, property taxes, insurance, utilities, HOA fees during the project. 2% - 5%
Selling Costs Real estate agent commissions (5-6%), closing costs, staging, marketing. 7% - 10%
Profit Margin Your reward for the risk, labor, and capital. 10% - 15% (Minimum)

If you don't account for these, your "great deal" evaporates. I once saw an investor nail the repair budget but forget about six months of HOA fees on a condo flip. That $2,400 oversight turned a modest profit into a break-even project.

How to Apply the 70% Rule: A Step-by-Step Walkthrough

Let's move from theory to practice with a real-world scenario. This is how I analyze every single deal.

Case Study: The 1978 Ranch House

Step 1: Determine the ARV. The subject property is a 3-bed, 2-bath ranch in a stable suburban neighborhood. I pull comps from the last 90 days. Three nearly identical homes, fully renovated, sold for $310,000, $305,000, and $315,000. Taking a conservative average, I set my ARV at $310,000. I don't use the high number hoping the market will rise.

Step 2: Estimate Repair Costs. I walk the property with my contractor. We need a new roof ($8,500), updated kitchen ($15,000), new flooring throughout ($7,000), paint inside and out ($5,000), and miscellaneous electrical/plumbing ($4,500). That's a base of $40,000. I immediately add a 15% contingency ($6,000) for unknowns. My total Estimated Repair Cost is $46,000.

Step 3: Run the 70% Rule Formula.
MAO = ($310,000 x 0.70) - $46,000
MAO = $217,000 - $46,000
MAO = $171,000

Step 4: Analyze the Result. The seller is asking $190,000. According to the rule, my maximum offer is $171,000. There's a $19,000 gap. This tells me one of three things: 1) The seller's price is too high for a flip, 2) My ARV or repair estimates are off, or 3) This isn't a 70%-rule deal. I might still negotiate, but I know exactly where my risk line is drawn.

If I offered the asking price of $190,000, my total project cost (purchase + repairs) would be $236,000. After selling costs (~8.5% = $26,350) and holding costs (~$8,000), I'd need to sell for over $270,350 just to break even. That's 87% of my ARV, leaving almost no room for profit or error. The rule prevented a bad decision.

The 3 Most Common (and Costly) Mistakes

Here's where that "10 years of experience" perspective comes in. These aren't the obvious mistakes; they're the subtle ones that eat away at your margins.

Mistake 1: Using an Overinflated ARV

This is the killer. Investors get excited and use the top-of-market comp, or they assume their fantastic renovation will command a premium no one else gets. The ARV must be based on what similar homes are actually selling for right now, not Zillow's algorithm or your gut feeling. In a shifting market, using comps from 6 months ago can be disastrous. Always be the most conservative person in the room when setting the ARV.

Mistake 2: Underestimating the "Soft" Holding Costs

Everyone budgets for repairs. Many forget the clock starts ticking the day they close. Property taxes, insurance, utility hookups, lawn care, and loan interest (especially on private money loans at 10-12%) add up fast. A 6-month project delay can add thousands. The 70% rule's 30% cushion is supposed to cover this, but if you've already squeezed that cushion thin by overpaying, you have no buffer left.

Mistake 3: Treating the Rule as Inflexible Law

This might sound contradictory, but slavish devotion is a mistake. The 70% rule is a starting point, not a finish line. In hyper-competitive seller's markets, finding a true 70% deal is like finding a unicorn. Blindly sticking to it means you'll never buy a property. The key is to know why you're deviating. Are you faster and more efficient than the average flipper, allowing for a lower contingency? Is it a premium neighborhood where the sell-through is faster, reducing holding costs? If you break the rule, you must have a specific, justifiable reason rooted in your unique strategy or market knowledge.

When and How to Adjust the 70% Rule

The market isn't static, and neither should your analysis be. The 70% rule originated in a different interest rate and inflation environment.

The 70% Rule is a Guideline, Not a Gospel. The number itself can flex. In a slow, buyer-friendly market with high inventory, you might aim for 65% to build a bigger profit buffer. In a insane seller's market with low inventory and rapid sales, you might have to accept 75-80%. But here's the critical adjustment: if you go to 80%, you must compensate elsewhere. Maybe you only do light cosmetic flips with very predictable, low repair costs. Maybe you have a direct-to-buyer sales strategy that eliminates agent commissions. The rule's components are levers you can pull, but the goal—protecting your profit—remains fixed.

For example, on a fast cosmetic flip with a reliable contractor and a hot neighborhood, my formula might look more like: MAO = (ARV x 0.75) - (Repairs x 1.10). I've tightened my repair contingency because the scope is simple, but I'm still using a disciplined formula. The worst thing you can do is abandon the structured thinking the rule provides.

Your Burning Questions Answered

Can you use the 70% rule in a super hot market where every house sells over asking?
You can, but it will mostly tell you what deals not to pursue. In those markets, the 70% rule acts as a filter to keep you from getting into bidding wars on properties that only work for retail buyers or long-term landlords. Your job becomes finding the ugly, off-market deals everyone else is overlooking, or adjusting your strategy to a higher percentage with extreme precision on every other cost variable. Sometimes, the right move in a hot market is to wait or look elsewhere.
What's the one cost almost every new flipper forgets to include in their 70% rule calculation?
Carrying costs for the period after the renovation is complete but before the house sells. You budget for 4 months of renovations, but what if it takes 2 months to get an offer and another 45 days to close? Those 3 extra months of mortgage payments, taxes, and utilities can be a $5,000-$10,000 surprise. Always add at least 2-3 months of post-renovation holding costs to your model.
Is the 70% rule still relevant with today's higher interest rates and construction costs?
It's more relevant than ever, but the pressure it reveals is greater. Higher loan costs eat directly into the 30% cushion. Increased material and labor costs make repair estimates more volatile, necessitating a larger contingency. The rule doesn't become obsolete; it just shows you that the margin for error is thinner. It might mean your profit target shrinks from 15% to 10%, or you have to be even more aggressive on purchase price. The rule is the diagnostic tool telling you the market conditions have changed.
How do you accurately estimate repair costs before you own the property?
You never will be 100% accurate, which is why the contingency is non-negotiable. The goal is to be 90% accurate. This comes from doing walkthroughs with an experienced contractor (pay them for this consult if you have to), creating a detailed line-item scope of work for every room and system, and getting actual quotes for big-ticket items like roof, HVAC, and kitchen cabinets. For the first few flips, overestimate everything. Assume every wall has hidden plumbing and every floor has rotten subfloor. Experience teaches you what's typical, but paranoia protects your bank account.

Look, the 70% rule won't make you a great house flipper. Only experience, a good team, and hard work can do that. What it will do is keep you in the game long enough to gain that experience. It forces a discipline that separates the hopeful from the profitable. Start with it as your iron law. Then, as you get a dozen deals under your belt and truly understand where every dollar goes, you'll learn when to bend it. But never forget the fundamental math it protects: your profit is not what you sell for, but what you keep after every single cost is paid.