# What is job costing? A plain-English definition, with a worked example

> Job costing is figuring out what one job really cost you, then setting it against what you billed. Here's the definition, the four costs most shops undercount, and one job run line by line.

Source: https://toolbagcrm.com/blog/what-is-job-costing-with-a-worked-example/
Author: The Toolbag Crew
Updated: 2026-10-26

What one job cost you versus what you charged, with a water heater job run line by line.

Job costing is adding up everything one job cost you, then setting that number against what you charged. That’s it. One job, start to finish, on its own, not the month and not the average across every job you ran. Where people trip is confusing it with bookkeeping, or with pricing. Bookkeeping tells you how the whole business did. Pricing is the guess you make before you ever swing a hammer. Job costing is the receipt that comes after, and it’s the only one of the three that tells you whether a specific job was worth doing.

## The definition, and what it isn't

Strip away the accounting words and it’s simple. You take what the customer paid. You subtract what that job actually ate: the hours, the parts, the gas, the little stuff nobody bothers to write down. What’s left is what the job made you. A whole-business profit number can’t tell you that. It blends your winners and your losers into one average, and the average hides the exact thing you need to see, which jobs pull their weight and which ones quietly cost you money just to show up.

## The four things that count as cost

Most shops nail the price and blow the cost, because they only count half of what a job eats. Four buckets, and **the last two are where the money hides**.

### The four buckets

- **Labor**: Every hour anyone put in, at what that person actually costs you. Not their take-home. The loaded number, with payroll taxes and whatever you carry on top.
- **Materials**: Parts, fittings, the box of screws, the dump fee. What you paid at the counter, not what you marked it up to.
- **Direct costs**: The permit, the rental, the sub you brought in, the fuel out and back. Anything that job made you spend that you wouldn't have spent sitting at home.
- **Overhead**: This job's slice of the rent, the insurance, the truck payment, the phone, the software. Everybody skips it, and it's why a job that looks like a winner often isn't.

Track the first two, miss the last two, and your numbers will look great right up until the bank balance calls you a liar.

## One job, run end to end

Here’s the whole thing on a real job. You’re a plumber. Water heater swap, quoted and billed at $2,400.

You and a helper are on it six hours. Loaded, you cost yourself $65 an hour and the helper runs $38. Six hours each: that’s $390 and $228, so $618 in labor. The heater and the fittings came to $900 at the supply house. You pulled a $75 permit and burned about $25 in fuel round trip, so call the direct costs $100. Add the hard numbers, $618 plus $900 plus $100, and you’re sitting at $1,618. Looks like $782 left over. Nice day.

Now the part that gets skipped. Your overhead runs whether you work or not, the rent, the insurance, the truck, the phone, all of it, and spread across the jobs you actually run it lands somewhere near $300 a day. This one took most of a day, so it carries maybe $240 of that load. Knock that off the $782 and you’re at $542. That’s what the water heater really made you. Still a good day, don’t get me wrong. But it’s $542, not $782, and that gap is the number nobody quoted and everybody lives on.

> $782 looked like the profit. $542 was the profit. The $240 you can't see is the part that pays your rent.

## The habit is the hard part, not the math

You can read the definition in ten seconds. Doing it on every job is where it falls apart. Run that same receipt job after job for a quarter, though, and the pattern walks right up to you. The water heaters pay. The drain calls, once you count the drive time and the one that came back as a callback, barely clear. You stop guessing which work to chase, because now you actually know [which jobs make money](https://toolbagcrm.com/blog/job-costing-which-jobs-make-money/).

## Where ToolbagCRM fits

The reason shops don’t job-cost isn’t the math. It’s that the pieces live in five places: the hours buried in a text thread, the materials on a receipt in the truck, the invoice in one app, the permit in a drawer somewhere. By the time you’d chase it all down, the next job has started and you’ve given up. Keeping the hours, the materials, the invoice, and the photos on one job record is what makes it happen at all. In ToolbagCRM each job carries its own labor, parts, and billing together, so the receipt adds itself up instead of waiting on you to rebuild it from memory a month later. You can [get started](https://app.toolbagcrm.com/signup/) free with no card, and Founders is free the first month, then a flat base rate with unlimited users. [See plan terms, plug-in slots, and payment fees.](https://toolbagcrm.com/pricing/)

> The dollar figures here are an illustration to show the method, not real rates. Your loaded labor cost, your overhead per day, and your material prices are yours to pull from your own books.

- [Field service management software](https://toolbagcrm.com/field-service-management-software/)
- [get started](https://app.toolbagcrm.com/signup/)
- [Plumbing CRM](https://toolbagcrm.com/crm-for-plumbers/)
- [HVAC CRM](https://toolbagcrm.com/crm-for-hvac/)
- [Electrician CRM](https://toolbagcrm.com/crm-for-electricians/)
- [Field service CRM](https://toolbagcrm.com/field-service-crm/)

## Frequently asked questions

### What is job costing?

Job costing is adding up everything a single job cost you, including labor, materials, direct costs, and overhead, then comparing that total to what you billed. It tells you what one specific job actually made, not the business average.

### What costs should be included in job costing?

Four things: labor at your loaded hourly cost, materials at what you paid, direct costs like permits, rentals, subs, and fuel, and a share of overhead such as rent, insurance, and the truck payment. Skipping overhead is the most common mistake.

### What is the difference between job costing and bookkeeping?

Bookkeeping tracks how the whole business is doing over time. Job costing zooms in on one job to show whether that job alone made money after every cost it created.

### Can you give a simple job costing example?

On a $2,400 water heater job with $618 labor, $900 materials, and $100 direct costs, the hard cost is $1,618. Subtract about $240 of overhead for the day and the real profit is roughly $542, not the $782 the hard numbers alone suggest.

## Related resources

- [Job costing: figuring out which jobs actually make money](https://toolbagcrm.com/blog/job-costing-which-jobs-make-money/)

- [How to price & quote jobs so you actually profit](https://toolbagcrm.com/blog/how-to-price-and-quote-jobs-for-profit/)

- [Margin vs. markup: why mixing them up costs contractors money](https://toolbagcrm.com/blog/margin-vs-markup-contractors/)

- [Flat-rate vs. time-and-materials: when to use which](https://toolbagcrm.com/blog/flat-rate-vs-time-and-materials-when-to-use-which/)

- [Founders pricing](https://app.toolbagcrm.com/signup/)