What is job costing in simple terms?

Tracking what each individual job cost you, so you can compare it to what that job paid you. Instead of one profit number for the business, you get one per job.

Do I need job costing if I am a one-person business?

If your work comes in distinct jobs and they differ in size or type, yes. A solo contractor running eight jobs a year has eight different outcomes hiding inside one profit number, and the difference between the best and the worst is usually where the money is.

What is the difference between job costing and just categorizing expenses?

Categorizing tells you how much you spent on materials this year. Job costing tells you how much you spent on materials for the Alvarez bathroom. Only the second one lets you calculate a job margin.

Do I need special software for job costing?

No. A disciplined spreadsheet works, and plenty of contractors run one successfully. What software changes is the discipline cost: the tagging happens as you record the transaction rather than as a separate weekly chore that gets skipped when you are busy.

What is job costing?

Updated July 27, 20266 min readWritten by the WIPKeep team

The short answer

Job costing is the practice of tracking every cost against the specific job that caused it, so you can measure the profit of each job rather than only the profit of the whole business. It requires three things: a job to tag costs to, somewhere to hold those costs while the job is open, and a close at the end where costs and revenue meet and the real margin appears.

Key takeaways

Job costing answers one question: did that job make money, and how much.
A profit and loss statement for the whole business cannot answer it, because good jobs and bad jobs cancel each other out inside the total.
The costs that matter most are materials, subcontractors, direct labor, equipment rental and permits. Chasing perfect allocation of shared overhead is usually wasted effort.
Without job costing you are bidding the next job using the average of jobs you have never actually measured.

Here is the situation job costing exists to fix. At the end of the year your books say the business made $61,000. You worked every weekend. You have no idea which of the fourteen jobs you ran were the ones worth doing, so next year you bid the same way and hope.

A business-level profit number hides everything. Two jobs at plus $14,000 and minus $9,000 look identical, in the total, to two jobs at plus $3,000 and plus $2,000. Job costing separates them.

What job costing actually requires

Something to tag costs to
A job, a project, a work order, whatever you call it. Every cost that exists because of that job gets attached to it at the moment you record it.
Somewhere to hold those costs while the job runs
This is the part people skip. Costs on an unfinished job should not be sitting in this month's expenses, because the revenue that pays for them has not arrived. See work in progress.
A close, where the job ends
At completion the revenue is recognized, the accumulated costs are released against it, any deposit is applied, and the margin becomes a fact rather than a feeling.

Which costs belong to a job

Direct job costs versus overhead
Cost type	Job cost?	Notes
Materials bought for the job	Yes	The clearest case. Tag it at purchase.
Subcontractor invoices	Yes	Also track them by vendor for 1099 season.
Direct labor on the job	Yes	Hours worked on that job, at your loaded labor cost.
Equipment rental for that job	Yes	The lift you rented for one roof.
Permits and inspection fees	Yes	Job-specific and unavoidable.
Dump fees for that job's debris	Yes	If you can attribute it, attribute it.
Truck payment, insurance, phone	No	Overhead. Serves every job.
Your own admin time	No	Real, but allocating it costs more than it tells you.
Small consumables from the truck stock	No	Not worth the tracking effort at this size.

A worked example: one bathroom remodel

The numbers below are an illustration, not customer data.

You bid an Alvarez bathroom at $18,500. The customer pays a $5,000 deposit in March. Work runs March to May.

Costs tagged to the Alvarez bathroom
Cost	Amount	When
Tile, fixtures and vanity	$4,850	March
Plumbing sub	$2,400	April
Electrical sub	$1,400	April
Framing and drywall materials	$1,180	April
Your labor, 68 hours at $45 loaded cost	$3,060	March to May
Permit	$310	March
Dumpster	$420	March
Total job cost	$13,620

While the job runs, that $13,620 accumulates as work in progress on your balance sheet. The $5,000 deposit sits as a liability. Your profit and loss statement for March and April shows neither, which is correct, because nothing has been earned yet.

In May the job finishes and you close it:

Closing the Alvarez bathroom

Account	Debit	Credit
Unearned RevenueApplying the deposit you were holding	$5,000.00
Accounts ReceivableThe balance the customer still owes	$13,500.00
RevenueThe full contract, recognized at completion		$18,500.00
Total	$18,500.00	$18,500.00

Debits equal credits. And in the same close, the accumulated costs are released:

Releasing the job's costs

Account	Debit	Credit
Cost of Goods Sold	$13,620.00
Work in Progress: Alvarez bathroomThe balance sheet holding account empties out		$13,620.00
Total	$13,620.00	$13,620.00

Debits equal credits. Revenue $18,500 less costs $13,620 leaves gross profit of $4,880, which is a 26.4 percent margin, recognized in May.

What you do with the answer

A 26.4 percent margin is only useful next to other numbers. Run five bathrooms and you learn what a bathroom actually returns for you. Run five bathrooms and five decks and you learn which one to chase and which one to price higher or decline.

Bid the next one from data. Your last four kitchens averaged 22 percent. Bidding the fifth at a number that implies 31 percent is a decision, not a hope.
Find the leak. A job that came in 12 points under its siblings has a reason, and the cost detail usually names it.
Learn which customers are expensive. Change orders, callbacks and slow decisions show up in the labor line.
Price your overhead in. Gross margin has to cover the truck, the insurance and your admin time before any of it is profit.

In WIPKeep: the Close Project screen

Pick the project
Enter the sale price
Invoiced (A/R) or Received (cash/checking)
Choose the customer, or a walk-in buyer
Closing costs and who they were paid to, if any

Closing is a form, not a typed sentence. You fill in those fields and press Close Project, and WIPKeep runs the whole close as one reviewed step: revenue recognized, work in progress cleared to cost of goods sold, and any customer deposit applied to the sale so only the balance is billed. Any time before that, one click on the job shows the costs sitting in WIP right now, account by account, plus deposits already received, so you can price a change order or decide to close against real numbers. The finished job's profit lands in its report. Closed it too soon? A controlled reopen reverses the whole closing batch and keeps the audit trail intact.

Frequently asked questions

What is job costing in simple terms?: Tracking what each individual job cost you, so you can compare it to what that job paid you. Instead of one profit number for the business, you get one per job.
Do I need job costing if I am a one-person business?: If your work comes in distinct jobs and they differ in size or type, yes. A solo contractor running eight jobs a year has eight different outcomes hiding inside one profit number, and the difference between the best and the worst is usually where the money is.
What is the difference between job costing and just categorizing expenses?: Categorizing tells you how much you spent on materials this year. Job costing tells you how much you spent on materials for the Alvarez bathroom. Only the second one lets you calculate a job margin.
Do I need special software for job costing?: No. A disciplined spreadsheet works, and plenty of contractors run one successfully. What software changes is the discipline cost: the tagging happens as you record the transaction rather than as a separate weekly chore that gets skipped when you are busy.