M40 Traffic Statistics
How much traffic does the M40 carry, and what kind? This page gives the headline figures from the Department for Transport road traffic statistics for 2025, and explains how to read them. Two further pages go into detail: one ranks every stretch, the other looks at lorries.
The headline numbers
| Measure | 2025 |
|---|---|
| Count points on the M40 | 33 |
| Busiest count point (J1A to J2) | 136,403 vehicles a day |
| Average across all count points | 85,733 vehicles a day |
| Busiest main-line stretch north of Oxford (J14 to J15) | 113,433 vehicles a day |
| Quietest main-line stretch (J8 to J9) | 70,986 vehicles a day |
| Highest lorry share on the main line (J11 to J12) | 12.3% |
What an annual average daily flow means
Each figure is an annual average daily flow: a year’s traffic past one M40 count point, divided evenly across its days, with the London-bound and Birmingham-bound carriageways combined. It smooths out weekday peaks, quiet Sundays and holiday weekends into one number.
Some count points are counted by people or equipment on the road in that year. Others are estimated from earlier counts and traffic trends. On the M40, both kinds appear; the busiest point, between the M25 and Beaconsfield, is a counted one.
What the figures show about the M40
The M40 is two roads in one. The southern end, inside the M25 catchment and past Beaconsfield and High Wycombe, carries well over 100,000 vehicles a day. From the Chilterns north it mostly settles into a run of 88,000 to 101,000, with a quieter stretch east of Oxford and a busier one around Warwick and Leamington.
The mix changes too. At the London end cars and taxis make up about three-quarters of traffic and lorries around 6%. North of Oxford the lorry share rises to between 8% and 12%.
Look deeper
- How busy is the M40? — every stretch ranked from busiest to quietest.
- M40 lorry and freight traffic — where the lorries are.
- Northbound and southbound pages — the same counts split by direction.
A note on duplicates
The Department for Transport sometimes records one stretch at several count points where it crosses a council boundary, and gives each the same figure. On the M40 this happens between Junctions 5 and 6, 8 and 9, 10 and 11, and 11 and 12. Our tables show each measurement once, so the 33 count points become 17 main-line stretches plus a few link roads.
The same figures appear on each of our junction pages, so you can see the count for the stretch you drive.
Traffic count figures on this page are from the Department for Transport road traffic statistics, 2025.