How to Calculate Rehab Costs

Estimating renovation costs is the single most important skill for a real estate investor. If you overestimate, you miss out on great deals. If you underestimate, you lose money. Use our calculator below to get a baseline estimate, then read our deep-dive guide on how to master the numbers.

The Art and Science of Rehab Estimation

Real estate "flipping" shows make rehab look easy. In reality, calculating rehab costs requires a systematic approach. You cannot simply walk into a house and "feel" that it needs $30,000. You need a Scope of Work (SOW) that accounts for every square foot and every major system.

1. The Square Foot Method (The Quick Check)

When you are first analyzing a deal, you don't have time to call three contractors. You need a "back of the envelope" calculation. Most professional investors use a tiered square foot pricing model:

• Low End ($15 - $25/sqft): This covers "lipstick" renovations. Think interior paint, new carpet, light fixture updates, and professional cleaning.
• Medium End ($35 - $55/sqft): This is your standard flip. It includes everything in the low end plus a full kitchen remodel (cabinets/counters), updated bathrooms, and potentially some new windows.
• High End ($75+/sqft): This is a gut rehab. You are moving walls, replacing plumbing and electrical, and perhaps addressing foundation issues.

2. Identifying the "Big Five" Killers

While the square foot method is great for interiors, it often fails to account for the major systems that can sink your budget. Always inspect these five items separately:

• The Roof: Depending on size and material, a new roof can range from $8,000 to $20,000+.
• HVAC: A full furnace and AC split system usually costs between $6,000 and $10,000.
• Foundation: Cracks or bowing walls can cost anywhere from $5,000 to $30,000. Never guess on foundation; get an expert.
• Electrical: Replacing an old knob-and-tube system or upgrading a panel can add $5,000 to $12,000.
• Plumbing: Re-piping a whole house with PEX is relatively affordable, but main sewer line replacements are not.

3. Creating a Detailed Scope of Work

Once a property is under contract, your estimate must become granular. A Scope of Work (SOW) is a document that lists every single task to be performed. This document serves two purposes: it gives you an exact cost, and it becomes the legal basis for your contract with your General Contractor.

Break your SOW down by room and then by trade (Plumbing, Electrical, Carpentry). This prevents "scope creep," where costs balloon because you forgot to account for small things like baseboards or outlet covers.

4. The Importance of the Contingency Fund

No matter how experienced you are, you will find surprises behind the walls. Termite damage, mold, or outdated wiring that wasn't visible during the walkthrough are common. Always add a 10% to 15% contingency to your final number. If your estimate is $50,000, your budget is actually $57,500.

Summary Checklist

• Measure total square footage accurately.
• Determine the level of finish required for the neighborhood (don't over-improve!).
• Check the age of the roof, HVAC, and water heater.
• Look for structural red flags (sloping floors, wall cracks).
• Get at least two bids from reputable contractors.
• Always include a 15% buffer for the unknown.