Job Costing: Why Your Quoted Margin Disappears

You price a job at 22% gross margin. By the time it ships, the actual margin is closer to 11%. The gap is real money and it happens on enough jobs that you know it is not a one-off. The question is where the cost went.

This is the most common conversation Result Marketing's founder Jared Loo has with manufacturing owners. He ran logistics and e-commerce at scale before building software, and the pattern was the same: quoted economics and actual economics diverged, and no one could explain why fast enough to act.

The Four Places Margin Disappears

Job costing failures are predictable. The variance almost always comes from the same four sources:

The problem is not that these things happen — they happen in every factory. The problem is finding out about them after the job is invoiced rather than while it is in progress.

Standard Cost vs Actual Cost: The Core Comparison

Job costing works by comparing what the job was supposed to cost (standard) against what it actually cost (actual). The gap is the variance, and variances have causes.

Standard cost is derived from your BOM and your labour routing: at standard material prices, standard yield, and standard hours, this job should cost RM X. Actual cost is the sum of what was actually issued, the hours actually logged, and the overhead actually absorbed.

Without a system that captures actual consumption in real time, you can only calculate this comparison at month-end — by which point the job has shipped, the invoice is out, and you cannot adjust the price.

What "In-Job" Visibility Changes

When job costing is live rather than retrospective:

• A supervisor can see that Job #5041 has already consumed 94% of its material budget at 70% completion
• Finance can flag it before the job closes rather than discovering it in the monthly P&L
• The production team can investigate whether it is a BOM error, a material quality issue, or a process problem

This is the difference between a dashboard that explains the past and one that influences the present. The business dashboards and BI we build for manufacturers are designed around operational decisions, not just financial reporting.

Common Costing Mistakes in Singaporen SME Factories

Ignoring yield loss in the BOM. If your process loses 7% of input material and your BOM does not encode that, every job will show a material variance that looks like over-consumption when it is actually a structural BOM error.

Flat overhead rates applied annually. Overhead rates based on last year's production volume become inaccurate when volume changes. A job in a slow month absorbs too little overhead; a job in a busy month absorbs too much.

Labour booked to "production" not to specific jobs. When labour is posted to a cost centre rather than a job number, you cannot tell which jobs were expensive to run. All you see is that production labour is over budget.

Treating scrap as a write-off rather than a job cost. Scrap that is not allocated back to the job that generated it understates that job's actual cost and inflates the next period's material purchases without explanation.

Building a Job Costing System

A job costing system does not need to be complex. It needs three data feeds: material issues from the store (tied to job numbers), labour bookings from the floor (by operator and job), and a job-complete trigger that closes the cost card and compares it to standard.

The output — actual vs standard by job, by product, by period — gives management the information they need to tighten quoting, fix the BOM, or address a process inefficiency.

See everything we build for manufacturers at /industries/manufacturing.

FAQ

How often should job costing variances be reviewed?

Weekly is practical for most manufacturers. Monthly is the minimum. Daily review is possible with a live system and is useful for long-running jobs where early intervention is worth the most.

Can job costing work without a full ERP?

A focused job costing module can be built as a standalone system that connects to your existing stock and accounting tools. You do not need to replace your whole technology stack to get accurate per-job margins.

What is the first step to fixing margin leakage?

Audit your BOM yield factors. In most factories, correcting the BOM to reflect actual material consumption eliminates 50–60% of the "unexplained" variance before any other system change is made.

Margin leakage is a data problem before it is a production problem. Chat with us on WhatsApp and we will show you exactly where the numbers are hiding in your current setup.