Quick answer
Job costing measures the labour, materials, subcontractor costs, and overhead consumed by one job, then compares the total with job revenue. Use actual tracked labour hours, not estimated hours. The core formulas are job cost = labour + direct expenses + allocated overhead, and job profit = revenue − job cost.
This guide is written for agency owners, consultants, contractors, bookkeepers, and small service businesses that need profit by client or job who want time tracking to support better planning, billing, reporting, and project decisions.
Use five numbers for each job
A useful job record needs revenue, actual labour hours, a labour cost rate, direct expenses, and an overhead allocation. Revenue is what the client pays for the job, excluding taxes collected on behalf of a government. Direct expenses are costs attributable to that job, such as materials, travel, software bought for the work, or a subcontractor invoice.
The labour cost rate is not the client billing rate. It is the cost to the business of one working hour, including wages or owner compensation and any employment costs you choose to load into the rate. Overhead covers shared costs that cannot be tied neatly to one job, such as rent, general software, insurance, and administration.
- Revenue earned by the job
- Actual labour hours tracked against the job
- Internal labour cost per hour
- Direct materials, travel, and subcontractor expenses
- A consistent share of business overhead
Calculate labour from actual hours
Labour cost equals actual job hours × labour cost rate. If a job used 42 hours and the loaded labour cost is $38 per hour, labour cost is $1,596. Include all work required to deliver the job, not only the hours that appeared on the client invoice.
Estimated hours belong in the quote and the variance report, but not in actual job cost. Reusing the estimate after delivery hides the very difference job costing is meant to reveal. Track project management, client calls, rework, and handoff against the same job so the cost follows the work.
Allocate overhead with one stable rule
Small service businesses usually allocate overhead by labour hour, labour cost, or a percentage of revenue. No method is perfect. Choose the driver that best follows how the business consumes resources, document it, and apply it consistently enough to compare jobs over time.
An hourly overhead rate works well when people are the main constraint. Divide expected annual overhead by realistic annual productive hours, then multiply the rate by each job’s hours. Revisit the rate when staffing or fixed costs change, not whenever one job looks worse than expected.
Work through a complete job costing example
Suppose a client job earns $8,000. The team records 70 hours at a loaded labour cost of $40 per hour, so labour costs $2,800. Direct expenses are $650 and allocated overhead is $1,050. Total job cost is $4,500, leaving $3,500 of job profit.
Job margin equals profit ÷ revenue × 100. In this example, $3,500 ÷ $8,000 × 100 = 43.75 per cent. That percentage can now be compared with the quoted margin, similar jobs, and the minimum the business needs. The same revenue without actual hours could not answer any of those questions.
Review variance before and after delivery
During delivery, compare actual hours used and the latest hours-to-complete estimate with the original allowance. That gives the team time to discuss scope, change the plan, or ask the client to approve extra work. After delivery, compare estimated and actual cost by phase so the next quote uses evidence.
Keep the review about the estimate and the system before blaming an individual. A large variance may come from unclear scope, missing client inputs, a senior person doing junior work, or revision limits that were never enforced. The time entries should help locate the cause, not become a surveillance record.
When detailed job costing is not worth it
Skip elaborate allocation for a tiny, repeatable job when the cost of maintaining the model exceeds the decision it supports. A simple labour total plus direct expenses may be enough. The useful level of detail is the one that changes pricing, scope, staffing, or which work you accept.
Detailed job costing matters most for fixed-fee projects, work with several contributors, jobs with material expenses, and services whose margins vary widely. Start with consistent time by project and a handful of cost categories. Add detail only after a real question cannot be answered without it.
Where Zeitio fits
Zeitio helps teams connect tracked hours to clients, projects, tasks, reports, approvals, and invoices so time data becomes useful business context instead of another spreadsheet.
Start with simple time entries, review them weekly, and use the data to improve project planning, billing accuracy, and team workload decisions.
Compare Zeitio pricing or create a workspace to try the workflow.
Further reading
FAQs
What is job costing for a service business?
Job costing adds the actual labour, direct expenses, subcontractor costs, and allocated overhead consumed by one job, then compares that total with job revenue to calculate profit and margin.
What is the formula for job cost?
Job cost equals labour cost plus direct materials and expenses plus subcontractor costs plus allocated overhead. Job profit equals job revenue minus that total cost.
How do I calculate labour cost for a job?
Multiply actual hours tracked against the job by the internal labour cost per hour. Use a loaded rate that reflects wages or owner compensation and the employment costs included in your costing policy, not the rate charged to the client.
Should job costing use estimated or actual hours?
Actual job cost must use actual tracked hours. Keep estimated hours separately so you can compare the quote with reality, explain the variance, and improve the next estimate.
How often should job costs be reviewed?
Review live jobs weekly when they are fixed-fee, long-running, or at risk of scope change. Complete a final review after delivery so actual hours, expenses, profit, and estimate variance inform future pricing.