Stock turn is how many times a year your pitch sells through its average inventory. UK trade guidance puts the floor at 8 turns a year; the market-average pace of sale implies a theoretical ceiling closer to 13. The gap between those two numbers, multiplied by your margin per unit, is real money — and most of the inputs are arithmetic you can do on the back of an invoice.
This article does that arithmetic, shows its working, and is honest about which parts are published data and which parts are derivation.
What stock turn is
Stock turn = annual retail sales ÷ average stock held.
Worked example: you hold an average of 30 cars on the pitch and sell 240 cars a year. 240 ÷ 30 = 8 stock turns. Each slot on your pitch sells through roughly every 46 days.
Sell the same 240 cars off an average holding of 20 — by selling each car faster — and you turn 12 times. Same volume, same pitch, less capital tied up, and each slot is producing more often.
The metric matters because used car retail is fundamentally a capital-velocity business. Margin per unit matters, but margin per unit per slot per year is what actually pays the bills.
The benchmarks
UK trade guidance: Dragon2000, a UK dealer management system vendor, advises in guidance first published in 2017 and updated in 2022 that stock should turn at least 8 times a year, with an ideal stock-age policy of 60–90 days. (Dragon2000, "Stock Turn Simplified") Worth labelling clearly: this is trade guidance from a DMS vendor, not a market census — but it is a widely-used UK reference point.
US benchmarks: Cox Automotive's US used-car KPI guidance (2018) puts a good inventory turn at 12 a year, a great one at 16, with the highest-performing dealers turning their entire inventory every 20 days. (Cox Automotive, 2018, US) US market, different stocking dynamics — but a useful picture of what the top end of the discipline looks like.
So: 8 is the floor, 12 is good, 16 is exceptional.
The actual maths
Here is the part you will not find in a published study, because it is not one — it is arithmetic from verified inputs. We show the working so you can redo it with your own numbers.
Input 1 — pace of sale. The UK market-average used car sold in 27 days in April 2026. (Auto Trader Retail Price Index, April 2026)
Input 2 — margin per unit. The Dealer Auction Retail Margin Monitor for April 2026 — methodology: Dealer Auction sold prices vs the Auto Trader market average, models with 20+ units — reported the Tesla Model Y carrying an average potential margin of £4,400, and the Mazda CX-5 as the UK's fastest seller at 23 retail days. (Dealer Auction Retail Margin Monitor, April 2026)
The derivation:
- A pitch slot selling at the market-average 27 days turns 365 ÷ 27 ≈ 13.5 times a year — in theory, with instant restocking.
- A slot whose cars average 45 days turns 365 ÷ 45 ≈ 8 times a year — right at the trade-guidance floor.
- Now attach a margin figure. Using the Model Y's £4,400 as a worked example (it is one model's April 2026 figure, not a market average): 13.5 turns × £4,400 ≈ £59,400 of annual margin potential through one slot, versus 8 × £4,400 ≈ £35,200 at the slower pace.
Roughly £24,000 a year of difference, per pitch slot, from velocity alone — same car type, same margin per unit, different speed. Even if your real margin per unit is half the Model Y example, the shape of the result holds: the slot selling at market pace out-earns the slow slot by roughly two-thirds.
To be completely clear: this is the arithmetic, not a published study. Real operations have restocking gaps, prep time, and mixed stock. The point is not the precise figure — it is that velocity compounds, and the inputs to check it against your own operation are all public.
Where imagery enters the maths
Imagery does not appear anywhere in the stock-turn formula. So why is a photo platform writing about it? Because of what sits one level up from the formula: a car only sells fast if enquiries arrive fast, and the published data on what drives enquiries is unambiguous.
AutoTrader Canada's marketplace data (January–July 2022) found used listings with 11 or more photos generated 205% more Vehicle Detail Page views and 185% more leads. (AutoTrader Canada) A Motors.co.uk buyer survey (UK, 2013) found over two thirds of buyers would not contact a dealer without seeing a photo of the car first. (Motors.co.uk via Car Dealer Magazine)
Label that data for what it is: engagement data, not stock-turn data. Nobody has published a study connecting photo quality directly to turn rate. But the chain is short and each link is either published or simple logic: more photos → more views and leads (published) → more enquiries per week on sale → better odds of selling in week one rather than week five → faster days-to-sell → more turns. The full days-to-sell side of that chain is worked through in days-to-sell: how presentation moves the metric.
There is a second, less obvious entry point: time-to-live. A car that takes three days to photograph and edit before it goes live has added three days to its effective days-to-sell before a single buyer has seen it. At 8 turns a year, three days of listing lag per car is a meaningful fraction of each cycle. How dealers compress that is covered in how dealers save time on car photography.
What this means in practice
If your stock turn is at or below the 8-a-year UK trade-guidance floor, the levers are the usual ones — sourcing, pricing, prep speed. Presentation belongs on that list because it is the cheapest lever to pull and the only one that costs nothing to test.
The cost side is smaller than most dealers assume — a full breakdown is in what car photo editing actually costs, and the payback arithmetic is worked through in the ROI of car photo editing. Motuva's free tier covers 20 images a month at full output quality, no watermark, with studio library access — no card, no demo. Pro: 150 images and lets you build your own studios; Ultra: unlimited, and API access is Ultra-only. Plan details on Motuva pricing →.
Run the arithmetic above with your own average days-to-sell and margin per unit. Then decide whether the velocity end of your operation is getting the attention the numbers say it deserves.
Start free — no card, no demo →
Related reading: Days-to-sell: how presentation moves the metric → · What car photo editing actually costs →
Related reading
Days to sell a used car averages 27 in the UK (April 2026). What the metric means, why it matters, and where presentation honestly fits in moving it.
Manual photo editing costs dealers hours every week. Where the time goes in the old process and what changes with AI batch editing.
Spyne and CarCutter don't publish pricing. AI editing starts at £49. The full car photography cost breakdown — tools, time, and outsourcing included.
Does a £49–£99/month photo tool pay for itself? A worked car photo editing ROI example with labelled assumptions, honest evidence, and a free way to test it.