Job costing for small contractors
What job costing is, how work in progress actually behaves on your balance sheet, and how to tell whether a finished job made money. Written for one-person and small crews.
The short answer
Job costing means tracking every cost against the specific job that caused it, so you can tell what each job earned rather than only what the whole business earned. For a small contractor it answers one question: did that job make money, and how much. It needs three things: a job to tag costs to, a place to hold those costs while the job is open, and a moment where the job closes and the profit becomes real.
A contractor with five jobs running does not have one business. They have five small businesses that share a truck. Job costing is how you see them separately.
The pages below cover the mechanics without the construction-ERP vocabulary: what job costing is, what work in progress means when it lands on your balance sheet, and what has to happen when a job finishes.
Do you actually need this?
Not every business does, and it is worth being honest about that before you take on the tracking discipline. Job costing earns its keep when the jobs differ from each other. If every job you run is the same size, the same mix and the same duration, your overall margin already tells you most of what job costing would.
It starts paying when any of these are true:
- Your jobs vary in size, scope or trade mix, so one average hides several very different outcomes.
- Jobs run longer than a month, or cross your fiscal year end.
- You take deposits before starting work.
- You use subcontractors, whose costs are large and job-specific.
- You are quoting new work from memory and suspect the memory is generous.
The vocabulary, briefly
| Term | What it means here |
|---|---|
| Job cost | A cost that exists because of one specific job: materials, a sub, a permit, a rental |
| Overhead | A cost that serves the whole business rather than one job: insurance, the truck, your phone |
| Work in progress (WIP) | Accumulated costs on a job that has not finished, held on the balance sheet |
| Close | The moment a job ends: revenue recognized, WIP released, deposits applied, margin known |
| Completed contract | Recognizing a job's revenue when it finishes, rather than as it progresses |
| Percentage of completion | Recognizing revenue as work progresses. Standard for large commercial contractors, and not what WIPKeep does |
Guides in this section
What is job costing?
Job costing explained for small contractors: what it tracks, the three things it needs to work, and a full worked example from first receipt to final margin.
Updated July 27, 2026
What work in progress means on a contractor's books
What WIP is, why unfinished job costs belong on your balance sheet instead of your profit and loss, and the year-end problem it solves.
Updated July 27, 2026
Back to all guides, or see how job costing works in WIPKeep.