Job Costing Calculator (Budget vs Actual)

What the numbers mean

Budget used vs work done is the early-warning number. If 45% of the cost budget is gone and 40% of the work is done, the job is running about 12% hot. In week six you can still find out whether that is timing (materials bought ahead of use) or a real overrun (more hours than the quote assumed). At handover you can only write it off.

Projected final cost assumes the rest of the job runs at the same rate as the part done so far. It is a rough estimate, and a useful one: on a S$140,000 budget, 45% spent at 40% complete projects to about S$157,000, so roughly S$17,000 over.

Done but not yet billed is the cash-flow number. If 40% of a S$186,000 contract is complete and only the 10% mobilisation claim has been raised, S$55,800 of finished work is sitting unbilled while wages and supplier bills go out every week. That gap is usually funded by the overdraft.

The four things job costing needs

1. Every cost lands on a job when it is recorded: supplier bills, materials issued from stock, subcontractors, equipment hire. If it is not tagged at the moment of entry, someone has to allocate it later, and later usually means never.
2. Labour hours against the job. For most contractors and workshops labour is the biggest cost and the most invisible one. A timesheet that only feeds payroll tells you nothing about which job used the hours. The free timesheet calculator totals hours; the job needs them tagged.
3. Budget vs actual while the job runs, not in a month-end report.
4. Billing from the job, so cost to date sits next to billed to date. The free progress claim calculator handles the claim itself.

Can you do this in Xero or QuickBooks?

Partly. A "Job" tracking category shows costs per job for a handful of jobs. It will not show labour by job, a budget per job, or billed against cost, and the 100-option limit means archiving old jobs to make room. The Projects features on higher plans add time and estimates, which suits service firms. Contractors who issue materials from stock and bill in progress claims usually outgrow both once they run more than about twenty jobs at once.

A real example

In a fictional stainless-steel workshop set up for demonstration, welding four work tables was planned at 4 hours. The team clocked time against the operation: it took 6 hours 20 minutes. At the welding bay's S$70 an hour that is about S$163 of labour nobody quoted for, on one job, in one operation. Without time recorded against the job, it disappears into the monthly wage bill. Multiply it across a month of jobs and it is the difference between a good year and a flat one.

Questions

How do you calculate job cost? Add materials and supplier bills, labour hours multiplied by the hourly cost (wages plus levies and benefits), and subcontractor or other direct costs booked to the job. Compare the total with the job's cost budget and with the percentage of work done.

What is a projected overrun? The projected final cost (cost to date divided by the percentage complete) minus the cost budget. It assumes the rest of the job runs at the same rate, so treat it as a warning, not a forecast.

What hourly labour cost should I use? The fully loaded cost: basic wage plus CPF or levies, allowances and the share of paid leave, divided by the hours actually worked on jobs. For many trades that is 20% to 40% above the basic hourly wage.

What is the difference between job costing and project accounting? Job costing answers what a job cost and whether it made money. Project accounting adds revenue recognition, billing schedules, work in progress and retention, which long jobs with progress claims also need.