How to Estimate Rehab Costs Before You Buy

The rehab estimate is the number a flip lives or dies on — and the one buyers most often invent. “It needs about forty” is not an estimate; it is a guess wearing a hard hat. This page is a method for producing a rehab number you can defend: to yourself, to a lender, and to the math in your deal analysis.

Our running example is a $45,000 rehab budget on a house bought for $135,000 against a $260,000 ARV. The point is not the total — it is how the total was built.

Step 1 — Walk the property with a category list

Bring a fixed list of categories and inspect every one, even if the answer is “fine, $0”:

1. Demolition & cleanup — dumpsters, tear-out, haul-away.
2. Roof — repair vs. replace is often the single biggest swing in the budget.
3. HVAC — furnace/AC age and condition; a full replacement is a five-figure conversation in many markets.
4. Plumbing — supply and drain lines, water heater, fixture rough-ins.
5. Electrical — panel capacity, outdated wiring, code items an inspector will flag.
6. Kitchen — cabinets, counters, sink, layout changes (moving plumbing/electrical multiplies cost).
7. Bathrooms — per-bath cost depends heavily on whether tile and fixtures are replaced or refreshed.
8. Flooring — priced per square foot; note subfloor damage separately.
9. Paint & drywall — interior and exterior separately.
10. Appliances — the full package, including delivery and install.
11. Landscaping & exterior — curb appeal items, driveway, fencing, tree work.
12. Permits & fees — permit costs, inspections, architect/engineer if structural.
13. Miscellaneous — hardware, fixtures, cleaning, lock changes, the small items that add up.
14. Contingency — see Step 4. It is a line, not an afterthought.

For each category, note condition, scope (repair / refresh / replace) and a rough cost. Photograph everything — memory edits itself in the seller's favor. What belongs inside each line is spelled out in the rehab budget guide.

Step 2 — Price each category, conservatively

Use cost-per-square-foot references, supplier prices, and what local contractors actually charge — in that order of reliability, reversed. A national average is a starting point; a quote from the contractor who will do the work is an estimate.

Two disciplines separate estimators from guessers:

• Scope before price. “Bathroom: $7,500” means nothing until the scope says tile, tub, vanity, fixtures, and whether plumbing moves.
• Round up, individually. Every category rounded slightly up compounds into honesty. Every category rounded down compounds into a blown budget.

Step 3 — Get three contractor quotes, and compare line by line

One quote is a price. Three quotes are information.

• Give every contractor the same written scope, category by category, so the bids are comparable.
• Compare line by line, not just totals. In our sample's quote sheet, three bids totaled $43,050, $46,700 and $47,300 — but the cheapest mix (best line from each bid) was $42,950, and the cheapest total hid the most expensive kitchen. Totals conceal; lines reveal.
• A bid far below the others is not a bargain until you know what it excludes.
• Ask what is not included. Change orders born from exclusions are how “fixed” budgets grow.

Step 4 — Contingency is a real line

Budget a contingency of around 10% of the rehab total, and treat it as untouchable for upgrades. Contingency exists for the things a walkthrough cannot see: rot behind the shower wall, the sewer line, the panel that fails inspection.

Step 5 — Feed the number into the deal, then stress it

The $45,000 figure is not the end of the estimate; it is an input. In the sample deal (ARV $260,000, hard money at 85% loan-to-cost, 12%, 2 points, 6-month hold):

• At $45,000 rehab: net profit $41,660.
• At $67,500 (a 50% overrun): profit falls to $17,630 — survivable, barely.
• The MAO from the 70% rule is $137,000, so every rehab dollar you underestimate is a dollar straight off your margin.

Then keep the discipline after purchase: track plan vs. actual per category as invoices arrive. A kitchen overrun spotted in week two can be clawed back from flooring; spotted at the end, it cannot.

Tools

The free Lite version of our House Flip Analyzer runs the deal math on one sheet so you can test any rehab figure against profit, MAO and break-even instantly. The Full version adds the 14-category Rehab Budget sheet, a Contractor Quotes sheet that compares three bids line by line, an Expense Log whose actuals flow into the budget automatically, and Change Orders that revise the budget only when approved — the same plan-vs-actual discipline this page describes.

This page and the spreadsheets are calculation tools only and do not constitute financial, investment, tax, or legal advice. Rehab costs vary widely by market and scope; verify every figure with local contractor quotes before purchasing any property.