Capacity planning for a small workshop: how many cars a day is right?
How to set a realistic daily car capacity for your bays, why over-booking costs more than it earns, and how a capacity limit lets you automate booking safely.
A booking diary is only useful if it reflects what your bays can genuinely turn around. Over-book and you end up ringing customers to push them back, which costs you more goodwill than the extra job was worth. Under-book and you have technicians standing around at 3pm.
Start from bay hours, not car count
Count the productive hours you actually have: number of ramps multiplied by hours staffed, then subtract a realistic allowance for interruptions, parts collection, road tests and paperwork. Divide what is left by your average labour hours per job. That gives a car count grounded in reality rather than optimism.
Leave deliberate slack for the work you cannot predict
- Diagnostics that turn out to be bigger than the description suggested.
- Parts that arrive late or arrive wrong.
- MOT failures that need work the same day.
- Existing customers with genuine emergencies you will not turn away.
That MOT allowance is not guesswork. DVSA publishes MOT test results quarterly, and across all vehicle classes in the first quarter of the 2025 to 2026 financial year the initial fail rate was 26.80%, with a final fail rate of 21.54% once defects rectified at the test station are excluded DVSA, MOT test results by class of vehicle. If roughly a quarter of the tests you book turn into remedial work, your diary needs room for it.
A common approach is to hold back one slot a day. If nothing urgent lands, you use it for catch-up or an extra booking taken manually. Our piece on what the MOT data says about the work coming through your bay breaks down which failures are most likely to fill it.
Why a capacity number makes automation safe
The reason many garage owners distrust automated booking is the fear of a machine filling the diary with work they cannot do. A capacity limit removes that. In Garage Ghost you set the number of cars you will take per day, per day of the week. The AI books inside that ceiling and nothing beyond it. When the day is full, it offers the next available day instead.
You can change the number at any time — down for a technician's holiday, up for a quiet week you want to fill. If you want to see what filling those quiet days would be worth, put your own figures into the missed-call calculator.
Published Sources & References
- MOT test results by class of vehicle (statistical data set)(Driver and Vehicle Standards Agency)