The London Marathon course
35 m net downhill (41 m → 6 m).
The London Marathon is one of the flattest of the World Marathon Majors — Find My Marathon scores it 99 out of 100 for PR-friendliness — and its only real piece of terrain is a help, not a hill: a sustained drop off the Blackheath plateau in the first few miles that hands you roughly 40 m of free descent. That gift is also the trap. It feels effortless, so runners bank time well under goal pace and arrive at the technical middle miles already overdrawn. After the Cutty Sark the course flattens; the emotional peak is Tower Bridge at halfway, where the crowd is loudest and the temptation to surge is strongest. Then comes the genuine challenge: the Canary Wharf and Docklands miles from about 14 to 21, the quietest and most technical of the day, full of sharp turns, wind tunnels between the towers and GPS drift that makes your watch lie. The finish along the Embankment and up to The Mall is fast and flat. Pace London by even effort, treat the early downhill as banked discipline rather than banked seconds, and the flat second half is where a negative split lives. Note that London’s entry "Good for Age" scheme is separate from Boston qualifying — they are not the same standard.
Course segments
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Blackheath start & Charlton descent (0–7K) -0.5% · −38 m
The defining feature: the steepest sustained descent of any major, dropping off the Blackheath plateau. It tempts a fast, quad-trashing start — hold marathon effort.
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Greenwich & the Cutty Sark (7–19K) flat · −6 m
Largely flat past the Cutty Sark, where the noise around 11 km is the second over-pacing risk. The road narrows here.
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Tower Bridge & halfway (19–22K) +0.1%
A small rise onto Tower Bridge with the loudest crowd of the day at halfway — the biggest pace-spike danger. Bank effort, not seconds.
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Canary Wharf & the Docklands (22–33K) flat
The crux despite being flat: miles 14–21 are the quietest and most technical, with sharp turns, wind tunnels between towers and GPS drift. Run by effort.
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The City & the Embankment (33–40K) flat
Exceptionally flat, fast and crowd-charged — the place for a controlled push if you have it.
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Westminster to The Mall (40–42.2K) flat
Big Ben, Buckingham Palace and the final 385 yards on The Mall. Essentially flat — empty the tank.
Race-day weather
The London Marathon is run in April. A typical race morning is around 47 °F with a dew point near 44 °F (a temperature-plus-dew-point sum of 91), so no heat penalty in a typical year. If the forecast is warmer than usual, slow your goal with the heat-adjusted pace calculator before race day — heat is the most common reason a goal pace falls apart.
How this plan is built
Splits come from an even-effort, grade-adjusted model: your goal time is spread across the course by each segment's energy cost, so you hold the same effort up the hills and down them instead of chasing one flat clock pace. See the generic marathon pace calculator for a course-blind even pace, or browse marathon pace calculators by course for other majors.
Sources
- London Marathon official course TCS London Marathon — official course information (Blackheath/Greenwich start to The Mall finish, ~−35 m net).
- Course profile & PR-friendliness Find My Marathon — London Marathon elevation profile and PR score (start/finish elevation, "Mostly Flat").
- London April climate (temperature & humidity) Met Office / Weather Spark — average late-April weather for London (used to estimate race-morning temperature and dew point).
- Even-effort pacing (grade-adjusted cost) Minetti, Moia, Roi, Susta & Ferretti (2002), “Energy cost of walking and running at extreme uphill and downhill slopes”, J. Appl. Physiol. 93(3): 1039–1046.
- Race-day heat & humidity adjustment Mark Hadley / Maximum Performance Running — temperature + dew-point pace-slowdown method (air temp °F + dew point °F → % slowdown band).
FAQ
Is the London Marathon course flat and fast?
Yes — it is one of the flattest and fastest majors, a world-record course with only about 35 m of net drop and no significant climbs. The one notable feature is a downhill start off Blackheath. The real challenge is pacing discipline and the twisty, sometimes windy Canary Wharf section, not elevation.
How should I handle the downhill start at London?
Treat it as banked effort, not banked time. The Blackheath descent is the steepest sustained downhill of any major and it feels free, so most runners drift well under goal pace in the first 5 km and then fade in the technical middle miles. Hold steady marathon effort down the hill — the even-effort plan above keeps your early pace honest.
What is the hardest part of the London Marathon?
The Canary Wharf and Docklands miles, roughly miles 14–21. They are flat but mentally and technically demanding: the quietest crowds of the day, sharp turns, wind funnelling between high-rises, and GPS that drifts long so your watch reads short. Run this stretch by effort and feel, not by the number on your wrist.
What is the weather usually like for the London Marathon?
The late-April start is typically cool — around 46–48 °F with a dew point near 44 °F — and rarely muggy, which is part of why it is so fast. But it is volatile: 2018 was a record-hot ~75 °F. If your forecast is warm, slow your goal with the heat-adjusted pace calculator linked on this page.
Does a London time count as a Boston qualifier?
Only in the same way any certified marathon does — London is not a special BQ race. London has its own separate "Good for Age" entry scheme for getting into London itself, which is independent of Boston’s standards. Use the Boston qualifier calculator to check a BQ time, and do not confuse the two systems.
Estimates only. Segment elevations are approximate, drawn from public course profiles, and your real splits depend on fitness, fuelling, weather and pacing discipline on the day. Not medical or coaching advice.