Most owners of a garage know roughly how busy they are. Far fewer know whether they are actually making money on each job, where profit is leaking, or which part of the business is growing. Key performance indicators, or KPIs, answer those questions in a few numbers you can check every month.
This guide covers the 7 KPIs that matter most for a garage, how to calculate each one, and what to do when a number moves the wrong way.
Why KPIs matter more than turnover
Turnover tells you how much came in. It does not tell you whether prices cover costs, whether time is being used well, or whether cash will be there next month. A garage can grow turnover and still make less profit if costs grow faster. KPIs show you the drivers behind the result, early enough to act.
The 7 KPIs for a garage
1. Average job value
How to calculate it: Revenue ÷ jobs
Shows whether jobs are growing in size.
2. Labour hours sold
How to calculate it: Hours charged to customers
Your capacity.
3. Parts value
How to calculate it: Parts charged to customers
Parts margin is a big profit source.
4. Labour margin
How to calculate it: (Labour revenue − labour cost) ÷ labour revenue
Whether your labour rate covers technician costs.
5. Technician efficiency
How to calculate it: Hours sold ÷ hours paid
Shows lost time in the workshop.
6. Repeat customers
How to calculate it: Customers returning within 12 months ÷ customers
Service reminders drive this.
7. Comebacks
How to calculate it: Jobs redone ÷ jobs
A quality measure that protects profit.
Interpreting these measures in practice
Compare labour hours sold with technician hours paid, then inspect comeback rate and parts margin by job type. High workshop utilisation can conceal unpaid diagnosis, waiting for parts or warranty work. Track average invoice and repeat service bookings with customer complaints, not in isolation. If billed hours fall, identify whether the cause is appointment gaps, slow parts supply, rework or estimating before adding capacity. Review the same technician and job categories over comparable periods.
Start with the profit basics
Alongside the industry KPIs above, every owner should check four headline figures each month:
- Total income for the month and year to date
- Total costs, split into direct costs and overheads
- Net profit and operating margin
- Lowest cash balance in the next 12 weeks, from a cash flow forecast
If net profit is falling while turnover rises, look at the cost KPIs first. If cash is tight while profit looks fine, look at unpaid invoices.
An example month (illustrative figures)
Say a garage takes £18,000 in a month and spends £11,000 on the direct costs of delivering the work. Gross profit is £7,000, a gross margin of 39%. If last month the margin was several points higher on similar turnover, something has changed in prices, costs or the mix of work, and the KPIs above show where to look. These figures are illustrations only: use your own.
What to do when the numbers slip
- Pricing parts with a clear margin
- Service and MOT reminders for every customer
- Fixed-price service menus
- Specialising in hybrid and electric vehicles
Pick one action at a time, so you can see what made the difference. If you are asking what the business could pay you, read how much a motor mechanic earns in the UK.
How to review your KPIs every month
1. Update your records for the month: jobs, sales, costs and invoices. 2. Compare each KPI with last month and the same month last year, so seasonal swings do not mislead you. 3. Pick the one number that moved most in the wrong direction and find out why. 4. Decide one action for next month, such as a price change, a rota change or chasing a debtor. 5. Check the result at the next review.
Fifteen minutes a month on this routine is enough to catch most problems while they are still small.
Common mistakes with KPIs
Tracking too many numbers. Pick the handful that drive your profit and review them consistently.
Looking at one month in isolation. Trends matter more than single results.
Not acting on what you find. A KPI that never changes a decision is just a number.
Keeping figures in your head. Write them down, or let a spreadsheet calculate them, so nothing is guessed.
Run the numbers on your own business
The **Garage Management System** tracks every job, cost, invoice and VAT return, and works out your profit, margin and key figures automatically on a one-page dashboard. It costs £15 once, with no subscription. Before you open, work out your start-up costs with our free garage start-up calculator.
Frequently asked questions
What is the most important KPI for a garage? Gross margin, because it shows whether your prices cover the direct cost of each job. If it is wrong, growth only makes things worse.
Which KPIs should a new garage track first? Start with average job value, labour hours sold and parts value. They are quick to work out and show straight away whether your pricing and capacity are right.
Can KPIs help me set prices? Yes. If your margin or rate per job is below target, your prices are too low for your costs, however busy you are.
What is a good gross margin for a garage? There is no single benchmark, because margins depend on your mix of work, location and whether you pay staff. The useful test is your own trend: a margin that holds steady or rises as you grow is healthy, and a falling one needs action on price or costs.
How often should I check my KPIs? Monthly for most figures, and weekly for cash and unpaid invoices.
Do I need software to track KPIs? No. A spreadsheet that calculates the figures from your records works well for most small businesses and avoids monthly fees.