Contractor job costing: compare estimated and actual costs by task

1. Keep the original estimate as the comparison point

Save the estimate version used to plan the job before replacing any of its numbers. If you overwrite five estimated preparation hours with seven actual hours, the final worksheet may balance, but you have erased the two-hour miss you needed to study.

Use the same short task names in both records: preparation, application, setup and cleanup, materials, and other direct costs. Choose enough detail to explain the work without making recording burdensome. A one-room repaint does not need dozens of cost codes.

The small interior painting example demonstrates building these assumptions before the job. The review should follow those same boundaries afterward.

2. Record hours and purchases while the job is fresh

Record each person's time by task. Two workers spending three hours on preparation create six labor hours, not three. Keep travel and return visits in their assigned categories so they do not disappear into an unexplained labor total.

Attach the job reference to purchase records and note returns or materials retained for future work. The IRS recordkeeping guidance identifies invoices, receipts and paid bills as supporting business documents. For this operational review, those records help you trace an amount back to the actual purchase.

Use a consistent material-cost basis. Charging all purchased containers to the estimate but only consumed fractions to the actual column creates an artificial improvement. Document any inventory allocation with your bookkeeper.

3. Calculate the difference for each task

This hypothetical repaint uses a constant loaded labor cost of $35 per hour. The hours and dollar amounts are invented, not production benchmarks. Positive variances below mean costs exceeded the estimate; negative variances mean costs were lower.

Estimated labor totals 18 hours and $630; actual labor totals 20 hours and $700. The net labor difference is $70. Adding the $30 material increase and $10 saving elsewhere produces the $90 total overrun.

Divide that $90 by the estimated $960 to express the direct-cost overrun as 9.375%, or about 9.4%. Always name the denominator. A cost overrun percentage and a change in gross-margin percentage are different calculations.

4. Explain the variance before changing a production rate

The largest task miss is preparation: two extra hours and $70. Read the site notes. Was a repair missed during inspection, was access different from the assumption, or did the customer add another surface? Those causes need different responses.

If the original scope genuinely required more preparation, revise the inspection questions and future allowance for similar conditions. If the customer added work, keep that work and its approval separate. The scope-change guide explains what to record.

The application saving should also be examined. It might reflect easier access, fewer edges or a more efficient sequence. Do not lower every future application allowance based on one easier job.

5. Translate the overrun into the amount left

Assume the hypothetical selling price stayed at $1,280 and no scope was added. Estimated direct costs of $960 left $320, or 25% of the price. Actual direct costs of $1,050 leave $230: $230 ÷ $1,280 = approximately 18.0%.

The $90 cost overrun reduced the amount available for overhead and other expenses by the same $90. It did not reduce the gross margin by 9.4 percentage points; the gross margin fell by approximately 7.0 points because that calculation uses selling price.

This table excludes business overhead from both cost columns. It therefore does not calculate net profit. Review the markup and margin guide before labeling the remainder.

6. Finish the review after the missing costs arrive

A job can look better than it was when a rental bill or final time entry has not arrived. Mark the cost review provisional until those items are checked. Include known unpaid job costs in the operational comparison instead of treating their absence from the bank feed as a saving.

The SBA's finance guidance distinguishes money owed, bills payable and available cash. Keep those records alongside the job review: customer payment status answers a different question from what the work cost.

End with one or two specific actions, such as “measure damaged trim separately” or “include the second collection trip.” Assign a review date for the relevant estimating template rather than writing only “charge more.”

Estimate-versus-actual review checklist

• Preserve the original estimate and its scope version.
• Use matching task labels and cost definitions.
• Include every worker's hours and the owner's time.
• Reconcile receipts, returns and outstanding job costs.
• Calculate actual minus estimate consistently.
• Separate added scope, rate changes and productivity differences.
• Check the amount left before overhead, then update a specific assumption.

Use the estimate checklist when applying the lessons to the next proposal.

Questions about reviewing job costs

What if the actual hourly labor cost also changed?

Separate time and rate effects. If this example's 20 actual hours cost $37 each, actual labor becomes $740. Compared with the $630 estimate, the $110 difference consists of $70 for extra hours at $35 plus $40 from the $2 rate increase across 20 hours.

Should a cost overrun become an extra invoice?

A cost comparison is an internal learning tool. It does not establish permission to bill more. Review the agreed scope and pricing arrangement separately.

How many jobs prove a new production rate?

This method sets no universal sample size. Compare similar surfaces, access and preparation conditions, and note unusual events. Keep reviewing as more comparable records accumulate.

About this article

Prepared for the Quote Your Jobs blog. Worked examples use illustrative assumptions, not customer case studies or local market rates. Replace them with the actual scope, supplier information and costs for your job.