Job costing is the process of comparing what you expected a job to cost with what it actually cost. For contractors, builders and trades, it is one of the clearest ways to identify which jobs are making money and which ones are quietly eroding margin.
What a contractor job costing spreadsheet should track
A useful job costing spreadsheet does not need to be complicated. At minimum, it should let you record the quoted revenue, the original cost budget and the actual cost of labour, materials, subcontractors and other direct expenses.
The most important outputs are:
- Actual total job cost
- Actual gross profit
- Actual gross margin
- Budget versus actual variance
- Job status
Example: quoted profit versus actual profit
Suppose you quote a job at £12,000 with a £7,200 cost budget. On paper, that gives £4,800 gross profit and a 40% gross margin.
During the job, labour runs £700 over budget, materials run £500 over, and a subcontractor adds another £300. Actual cost becomes £8,700. The job still makes £3,300, but the actual gross margin has fallen to 27.5%.
Without job costing, the job can still feel profitable because cash came in. With job costing, you can see exactly where the margin moved.
Track costs by category
Separating actual cost into categories is useful because the total variance alone does not tell you what went wrong. If labour is consistently over budget, your estimating assumptions, productivity rates or labour charge-out need review. If materials are the problem, supplier pricing, waste, take-offs or allowances may need attention.
Use one row per job for management visibility
For many small contractors, a simple job register is enough for management reporting. Each row can contain one job ID, client, quoted revenue, budgeted cost, actual labour, actual materials, actual subcontractors, other cost, profit and margin. That makes it easy to compare dozens of jobs without opening a separate file for each one.
Watch budget variance before the job is finished
Job costing is most useful while there is still time to act. A job that has already finished cannot be rescued. If actual costs are being updated during delivery, you can spot overspend early and decide whether to control labour, renegotiate scope, raise a valid change order or tighten purchasing.
Connect job costing to estimating
The best feedback loop is simple: estimate the job, record actual results, then use the variance to improve the next estimate. Over time, your own completed jobs become the best pricing data for your business.
Use a ready-made contractor job cost tracker
The MarginRidge Job Cost Tracker & Profit Analyzer is built for this workflow. It tracks quoted revenue, budget, actual labour, materials, subcontractors, other costs, actual profit, actual margin and budget variance across up to 100 jobs.
If you also want estimating, margin-protected pricing, change orders and invoice tracking, use Contractor Profit OS instead.