Job cost per square foot

How to Calculate Job Cost Per Square Foot

Cost per square foot is the most common shorthand in residential construction — and one of the most misused. Homeowners use it to comparison-shop. Contractors use it to sanity-check estimates. But sqft pricing only tells half the story. This calculator shows you the full build-up: direct costs, overhead allocation, profit margin, and what you need to bid to actually make money.

Direct Costs vs. Total Costs

Your direct costs are the three buckets that show up on every job: labor, materials, and subcontractors. These are the costs you can tie directly to a specific project. But direct costs alone don't tell you what to bid — they don't include the cost of running your business.

Overhead includes everything it takes to keep your company operating: office rent, vehicles, insurance premiums, estimating time, administrative staff, software subscriptions, and the tools that don't get charged to any single job. Most residential contractors run 15–25% overhead as a percentage of revenue. To calculate your actual rate, divide your total annual overhead dollars by your annual revenue.

The Margin vs. Markup Problem

This distinction costs contractors real money every year. Markup is profit expressed as a percentage of your cost. Margin is profit expressed as a percentage of your selling price. They are not the same number.

• A 20% markup on a $50,000 job = $10,000 profit = 16.7% margin
• A 20% margin on a $50,000 job requires a 25% markup on costs
• Formula: Markup% = Margin% / (1 - Margin%)

If you want a 20% net margin after overhead, you need to mark up your overhead-loaded cost by 25%. Most accounting software reports margin. Most contractors think in markup. Make sure you're using the right number when setting your target.

Labor Burden: The Hidden Cost

Never bid using gross wages. Your actual cost to employ a worker includes FICA taxes (7.65%), federal and state unemployment insurance (roughly 3%), workers' compensation insurance (varies dramatically by trade — electrical might be 5%, roofing can exceed 15%), health insurance contributions, paid time off, and any tool or vehicle allowance. For most trades, burden adds 25–40% on top of gross wages.

A carpenter paid $30/hr gross actually costs you $38–42/hr fully loaded. If you're estimating 200 labor hours at $30/hr, you're leaving $1,600–$2,400 on the table before you even start. Use burdened labor rates in your cost inputs to this calculator.

When Square Foot Pricing Misleads

Cost per sqft is a useful sanity check after you've done the real estimate — not a substitute for it. Two projects of equal square footage can have vastly different costs based on:

• Finish level (builder-grade vs. custom cabinetry, tile, fixtures)
• Complexity (open addition vs. multi-story, structural changes)
• Site conditions (access, distance from supply house, existing conditions)
• Labor market (union vs. non-union, local labor rates)

The danger is using a competitor's sqft price without knowing their cost structure. A larger contractor with better supplier pricing and lower overhead can legitimately bid lower per sqft and still make money. You can't match that price without losing.

Validating Your Numbers

RSMeans (now Gordian) publishes region-specific cost data for nearly every construction task. NAHB conducts annual cost-of-construction surveys for residential builders. As a rule of thumb for residential remodeling: labor typically represents 30–40% of direct costs, materials 50–60%, subs 10–20%. If your ratios are significantly different, investigate before bidding.

After running your estimate, use the bid-per-sqft number from this calculator to compare against published benchmarks for your region and project type. If you're 30% above RSMeans for comparable work, either your costs are high or your overhead rate needs examination.