Actual job costing, and why estimates drift

Most manufacturers know their overall margin and very few know it per job. The gap between those two is where repeat work quietly stops paying.

Where the drift comes from

• Setup booked against run. A short batch carries a full setup; averaging the two makes small jobs look like large ones.
• Unbooked time. Work that happened but was never recorded has to land somewhere, and it usually lands in overhead.
• Material valued at a standard set years ago rather than at what was paid for the lot issued.
• Subcontract treated as an estimate because the invoice arrives after the job has closed.
• Rework booked to the original operation, so the job looks slow rather than looking like it went wrong.

What to record

Costing is only as good as the bookings underneath it, which is an argument for making booking easy rather than for insisting on discipline.

• Setup and run as separate bookings against the operation.
• Material issued from a specific lot, valued at what that lot cost.
• Subcontract cost against the consignment that went out.
• Rework as its own operation or job, not folded into the original.

Reading the result

Compare against the estimate the quotation was built from rather than against a standard cost. The estimate is what you sold; the standard is an internal convention.

Watch for lines reported as unvalued. A job with a missing rate is not a cheap job — it is an incomplete measurement, and treating a gap as a zero is how a loss-making part keeps getting quoted.

What this does not cover

This covers operational job costing, not statutory cost accounting or overhead absorption for financial reporting. Those stay with your accountant and your ledger.

Actual job costing in Keystone · Works orders and shop-floor booking