HVAC Job Costing Explained - Why Most Contractors Are Guessing Their True Margins

If you can't say how much labour went into each job, you're not really job costing—you're estimating margins from company-wide numbers. Real job costing ties every labour dollar to a specific job so you know true cost and margin per job.

Why Company-Wide Numbers Aren't Enough

Revenue minus total labour tells you if the company made money. It doesn't tell you which jobs made money. A few bad jobs can hide inside a "good" overall margin. Until you see labour spend per job in real time, you're guessing.

The Role of Labour in Job Costing

Labour is usually the biggest variable cost on a job. Materials are often tracked by job; labour is not. So the missing piece is: which hours (and thus which labour cost) belong to which job? Once you have job-coded time:

• You get labour cost per job from actual hours × rates (including overtime where it applies).
• You can compare that to the job's revenue and to your estimate.
• You can see which job types and which crews are profitable.

That's job costing. Everything else is approximation.

How Guessing Hurts You

When you guess margins, you underprice some work and overprice other work. You can't fix jobs that take longer than estimated if you don't know which jobs ran over. You also can't spot hidden payroll leakage that shows up as "missing" profit. Real numbers fix that.

What You Need to Job Cost Properly

1. Time tied to jobs — Techs log time to the job (or travel, admin, etc.). No unallocated hours.
2. Rates and overtime — So labour cost is hours × correct rate (regular vs overtime).
3. Comparison to revenue and estimate — Labour cost per job vs what you charged and what you quoted.

With that in place, you stop guessing and start managing. FieldCrew gives HVAC crews job-based time tracking and labour cost per job so you can see true margins and recover profit.