What Is Job Costing?
Job costing is a cost accounting method that tracks the actual cost of an individual project, job, or contract separately, rather than averaging cost across all production during a period. It is used whenever work is distinct enough, a specific construction project, a custom manufacturing order, a client engagement, that knowing its true, standalone cost and profitability matters more than knowing an average cost per unit.
How Job Costing Works
- Set up a job or project code.
Every cost related to this specific job will be tracked against this code.
- Track direct materials to the job.
Materials purchased or allocated specifically for this job are coded to it.
- Track direct labor to the job.
Hours worked on this specific job, at the appropriate labor rate.
- Allocate overhead to the job.
A share of indirect costs, using a consistent allocation method, applied to the job.
- Total the job's cost.
Sum of direct materials, direct labor, and allocated overhead gives the job's total actual cost.
- Compare against the contract or bid.
Actual job cost measured against what was quoted or budgeted reveals the job's real profitability.
Job Costing vs. Process Costing
- Job costing:
Tracks cost per distinct job or project, appropriate when each job is different enough that average cost per unit would not be meaningful, such as a custom home build or a bespoke manufacturing order.
- Process costing:
Tracks average cost across a continuous production run of largely identical units, appropriate when output is standardized, such as a beverage bottling line.
The choice between the two follows directly from how uniform the output is. A business making thousands of identical units benefits from process costing's simplicity; a business where every job is genuinely different needs job costing's per-job precision, since an average cost across dissimilar jobs would tell management very little about any specific one.
A Job Costing Example
EXAMPLE
A custom fabrication job: $8,200 in direct materials, 120 hours of direct labor at $45/hour ($5,400), and overhead allocated at $20 per labor hour (120 × $20 = $2,400).
Total Job Cost = $8,200 + $5,400 + $2,400 = $16,000.
The job was quoted at $19,500. Actual profit on this specific job: $19,500 − $16,000 = $3,500, an 18% margin, information a business tracking only total company-wide cost would never see at the individual job level.
Job Costing in Construction and Manufacturing
Construction is the industry most associated with job costing, since every project is inherently unique and profitability needs to be tracked project by project against its specific contract value, including any retainage and change orders that adjust that value along the way. The same logic applies directly to custom or made-to-order manufacturing, where each job or work order needs its own cost tracking rather than being averaged into a standard product cost.
This is why job costing and construction billing share so much infrastructure: the schedule of values that drives AIA billing is, in effect, the revenue side of job costing, while the direct materials, labor, and overhead tracked against that same job are the cost side.
Why Job Costing Accuracy Depends on Timely Invoice Coding
A job costing report is only as current and accurate as the invoices coded to it. If a supplier invoice for job materials sits unprocessed for weeks before being entered and coded to the correct job, the job's reported cost understates reality during that entire window, which can make an unprofitable job look profitable right up until the missing invoices finally post and the true picture appears, often too late to correct course on that specific job.
Consistent, prompt job coding on every invoice is what keeps job costing useful as a real-time decision tool rather than a report that only tells the truth in hindsight, after the job is already finished.
Frequently Asked Questions About Job Costing
Job costing is a cost accounting method that tracks the actual cost of an individual project or job separately, rather than averaging cost across all production. It is used when work is distinct enough that standalone cost and profitability need to be tracked per job.
2. What is the difference between job costing and process costing?
Job costing tracks cost per distinct job, appropriate when each job differs meaningfully, such as custom construction or manufacturing. Process costing tracks average cost across a continuous run of largely identical units, appropriate for standardized production.
3. What costs are included in job costing?
Direct materials specifically purchased or allocated for the job, direct labor hours worked on the job at the appropriate rate, and an allocated share of overhead, summed together to give the job's total actual cost.
4. Why is job costing important in construction?
Every construction project is unique, and profitability needs to be tracked project by project against its specific contract value, including adjustments from retainage and change orders, which a company-wide average cost figure would never reveal.
5. How does job costing relate to the schedule of values in construction billing?
The schedule of values represents the revenue side of a job, what will be billed for each scope of work. Job costing tracks the cost side, the actual materials, labor, and overhead incurred, allowing true job profitability to be measured by comparing the two.
6. Why does job costing accuracy depend on invoice processing speed?
A job costing report only reflects invoices that have actually been coded to that job. Delayed invoice processing understates a job's real cost during the delay, which can make an unprofitable job look profitable until the missing costs finally post.
