Rehab Cost Estimator: The Checklist That Catches Omissions

Introduction

Rehab budgets rarely fail because someone mispriced a kitchen. They fail because nobody priced the panel, the permits, or the dumpsters — and then the contingency that was supposed to absorb surprises gets spent on things that were never surprises at all.

TL;DR: The arithmetic here is addition. The value is the checklist. Every line stays visible whether or not you are spending on it, and the results count how many you left at zero — because a zero should be a decision you made, not a line you never saw. Contingency defaults to 15%, and on anything pre-1950 or structural it should be higher.

The formula

Hard costs  = sum of every line
Contingency = hard costs
              × contingency %
Total       = hard costs
              + contingency
Per sqft    = total ÷ square footage

On the defaults — a mid-grade cosmetic rehab on a 1,600 square foot single family:

• Interior (kitchen, baths, flooring, paint): $38,000
• Systems (HVAC, plumbing, electrical): $11,500
• Exterior (siding, landscaping): $5,000
• Soft costs (permits, dumpsters): $2,100
• Hard costs: $56,600
• Contingency at 15%: $8,490
• Total: $65,090, or about $41 per square foot

Note that roof and windows are at zero in that example, and the results say "2 checklist lines at zero." That is the calculator doing its actual job: prompting you to confirm you inspected the roof and decided it was fine, rather than never having thought about it.

Per-square-foot benchmarks

Per-square-foot is the fastest sanity check on any budget. Broad ranges, and they vary heavily by market and labour cost:

Scope	Typical range
Paint and carpet only	$10 – $20 /sqft
Cosmetic: kitchen, baths, flooring, paint	$25 – $45 /sqft
Cosmetic plus one or two major systems	$45 – $70 /sqft
Full gut, systems and layout unchanged	$70 – $110 /sqft
Full gut with layout changes or addition	$110 /sqft and up

The $41 in the example sits at the upper end of cosmetic, which is consistent with a scope that includes HVAC.

If your number falls well below the range for your scope, you have probably missed a line. If it falls well above, either your scope is larger than you think it is or you are over-improving for the neighbourhood — which is its own expensive mistake, since ARV is set by comparable sales, not by what you spent.

The lines people actually forget

The checklist is fixed because these are the omissions that recur:

Permits and inspections. Cheap relative to the project and expensive to skip — unpermitted work surfaces at resale, at appraisal, and sometimes with an order to undo it.

Dumpsters and haul-away. A full gut generates several pulls. At $400–700 each, this reaches four figures quickly.

The electrical panel. Not the outlets — the panel. Older houses commonly need a service upgrade before anything else can be permitted, and it is a five-figure line in some markets.

Windows. Easy to defer, and often the largest single line if they genuinely need replacing.

Landscaping. The first thing a buyer or tenant sees, and consistently the last thing budgeted.

The roof. Not forgotten so much as wished away. If it has under five years left, price it — the appraiser and the inspector will both find it.

Beyond the checklist, three costs sit outside a rehab budget but inside the deal, so do not lose them: holding costs while you own it, financing costs on the money, and your own time.

How much contingency

Contingency is not padding. It is the reserve for the things you could not see from the driveway, and the correct amount is a function of how much you could not see:

Situation	Contingency
Cosmetic work, recent construction, inspection done	10%
Standard cosmetic rehab, house built after 1980	15%
Pre-1950 construction, or any systems work	20%
Structural work, foundation, or unknown behind walls	25%+

Age is the strongest predictor. Older houses hide knob-and-tube wiring, galvanised supply lines, cast iron waste stacks, asbestos, lead paint and framing that was never square. None of it appears on a walkthrough and all of it appears once the walls open.

The discipline that matters: contingency is spent on discoveries, not on decisions. Upgrading the countertops after you started is not a contingency draw, it is a scope change — and treating one as the other is how a project runs 40% over while everyone insists nothing went wrong.

Where this calculator is deliberately simple

It does not price anything for you. Line-item costs vary by a factor of three across markets and by labour availability. A calculator that guessed your kitchen at a national average would be confidently wrong. Get bids for the top three lines.

No draw schedule or timeline. Cash-flow timing matters if you are funding rehab from a lender's draws — see the hard money calculator.

No holding costs. Taxes, insurance and utilities during the work belong in the flip or BRRRR analysis, not the rehab budget.

No labour-versus-materials split. Useful for managing a project, irrelevant to the total, and it doubles the data entry.

FAQ

How much does it cost to rehab a house?

For a cosmetic rehab — kitchen, bathrooms, flooring, paint — expect $25 to $45 per square foot in most markets, so $40,000 to $72,000 on a 1,600 square foot house. A full gut runs $70 to $110 per square foot and up. Both ranges move substantially with local labour costs and with how much of the systems work you inherit.

What should my rehab contingency be?

10% on cosmetic work in a newer house with an inspection done, 15% as a general default, 20% on anything pre-1950 or involving systems, and 25% or more where there is structural work or genuine unknowns behind the walls. Age of construction is the single best predictor of what you will find.

Should I get contractor bids before making an offer?

For the two or three largest lines, yes if the timeline allows — those are where a bad estimate does real damage. For the rest, a considered per-line estimate plus adequate contingency is usually enough at the offer stage. What you should not do is offer on a single per-square-foot number without having walked the property.

Does a rehab budget include holding and financing costs?

No, and mixing them causes real confusion. This budget is construction only. Holding costs (taxes, insurance, utilities while you own it) and financing costs (interest and points) are separate lines in the deal analysis. Keeping them apart is what lets you compare your rehab estimate against a contractor's bid.

Is a higher-end rehab worth it?

Only up to what comparable sales support. Over-improving relative to the neighbourhood is one of the most reliable ways to lose money on a flip — the extra $15,000 in finishes does not return $15,000 of ARV if no comp in the area sold at that level. Match the finish to the comps you underwrote.

How do I estimate a rehab I have not seen inside?

You do not, meaningfully. You can bracket it — square footage and age give you a plausible range — but a budget built without walking the property is a guess with a decimal point. If you must offer sight-unseen, make the inspection contingency real and price the top of your range.

Conclusion

Fill in every line, including the ones you are setting to zero, and then look at the count of zeros the calculator gives you. If it is high, walk the property again with that list in your hand. The cheapest money you will ever save on a rehab is the line you remembered before closing rather than after.