Finance8 min read

The Complete Guide to Job Costing for Contractors

BidBuild Team

Published January 10, 2026

Updated October 11, 2026

Job costing is the backbone of a profitable contracting business. Without it, you're essentially guessing whether each project is making or losing money. This guide breaks down everything you need to know.

What is job costing?

Job costing is the process of tracking all costs associated with a specific project — labor, materials, equipment, subcontractors, and overhead — so you can measure actual profitability against your original estimate.

Why does job costing matter?

Many contractors price jobs based on gut feeling or rough percentages. The problem? Small miscalculations compound across dozens of projects per year, quietly eroding your profits. Accurate job costing reveals:

Which types of projects are most profitable

Where you consistently over- or under-estimate

Which crews are most efficient

Whether your markup is sufficient

The Three Pillars of Job Costing

1. Direct Labor Costs

Track every hour your crew spends on a specific job. Include wages, benefits, workers' comp, and payroll taxes. A $25/hour worker actually costs you $35-$40/hour when you factor in burden.

2. Material Costs

Log every material purchase against the correct job. This includes delivery fees, waste factors, and returns. Pro tip: negotiate volume discounts with suppliers and track savings per job.

3. Overhead Allocation

Your trucks, insurance, office rent, and software don't bill to a single job — but they need to be accounted for. Most contractors allocate overhead as a percentage of direct costs or revenue.

Getting Started

Start simple. Track labor hours and material costs per job for 90 days. You'll quickly see patterns that inform better pricing decisions. Then layer in overhead allocation and subcontractor tracking.

The Technology Advantage

Modern job costing software like BidBuild Finance automates much of this process. Time tracking integrates with payroll, purchase orders link to job budgets, and dashboards show real-time profitability at a glance.

A worked example: costing one job

Example only. A bathroom remodel sells for $28,000.

Direct labor: 120 hours × $45 burdened rate = $5,400

Materials: $8,600

Subcontractors (plumber, electrician): $4,900

Permits and disposal: $700

Direct cost total: $19,600

Overhead runs 15% of revenue ($4,200), leaving $4,200 profit, or 15% net. If labor runs 30 hours over, that's $1,350 gone — about a third of the profit — from one line.

What is a burdened labor rate?

A $30-an-hour wage is not a $30-an-hour cost. Add payroll taxes, workers' comp, insurance, paid time off and the hours that can't be billed. Many contractors find their true cost is meaningfully higher than the wage. Calculate yours from last year's payroll records rather than using a rule of thumb.

Overhead allocation methods

Percent of revenue. Simple; works when jobs are similar.

Percent of direct cost. Better when material-heavy and labor-heavy jobs are mixed.

Per labor hour. Best when overhead is driven by crew size.

Pick one, apply it consistently, and revisit it once a year.

Common job-costing mistakes

Coding costs to "general" instead of a job

Ignoring committed costs (open POs)

Comparing to an estimate that was never updated for approved change orders

Reviewing job cost only after the job is finished

Getting started

Start with three cost categories (labor, materials, subs) on every job for one quarter. Get the habit right before adding detail.

Estimated vs. committed vs. actual cost

Estimated cost: what you expected the job to cost when you priced it.

Committed cost: money you've agreed to spend, such as issued purchase orders and signed subcontracts, even if no bill has arrived.

Actual cost: bills received and labor recorded.

Reading only actual cost makes a job look healthier mid-way than it really is. Committed plus actual is the honest picture of where a job will land.

Updating the budget for change orders

When a change order is approved, add its cost and price to the job budget the same day. Otherwise the job will look over budget for reasons that were already agreed and paid for, and real overruns become harder to spot.

How often should you review job cost during a job?

Look at each open job at least every two weeks. Compare percent of budget spent with percent of work complete. If 70% of the budget is gone and the job is half done, you still have time to talk to the client, adjust the plan or tighten purchasing. After the job is finished, all you can do is learn from it.

Using results to improve estimates

Keep a simple record for each finished job: estimated and actual cost by category, and a note on the largest differences. Before pricing a similar job, read the last few records. Over time your estimates rest on your own history instead of memory.

Choosing cost categories

Start broad and add detail only where it changes decisions. Labor, materials, subcontractors, equipment and other direct costs cover most jobs. Split a category further only when you'd act differently on the result, such as separating rough and finish carpentry because you price them differently.

Accurate job costing isn't just about knowing your numbers — it's about making confident decisions that grow your business sustainably.

Finance