The London Marathon course
35 m net downhill (41 m → 6 m).
From 41 m on Blackheath to 6 m beside Buckingham Palace, London hands back about 35 m net — nearly all of it inside the opening 7 km. Find My Marathon rates the course 99 out of 100 for PR potential, and the pacing problem is precisely that generosity: the early descent makes goal pace feel like jogging, the Cutty Sark roar near 11 km invites a second surge just as the road narrows, and Tower Bridge at halfway is the loudest, most dangerous place on the route to feel good. The bill lands between miles 14 and 21 in Canary Wharf — flat, but full of sharp turns, tower-funnelled wind, and GPS shadow that turns the watch into fiction. Runners who treated Blackheath as banked discipline own the finish: from 33 km the Embankment is flat, straight, and crowd-charged, the shape of a negative split, and the route sweeps past Big Ben toward the Palace before the last 385 yards on The Mall. One admin note: London's Good for Age scheme is its own entry system, not a Boston qualifying standard.
Course segments
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Blackheath start & Charlton descent (0–7K) -0.5% · −38 m
The plateau falls away almost immediately and keeps falling for 7 km — the defining decision of your London race. Hold marathon effort and let the grade pick the number; forcing a faster one here is quad damage on credit.
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Greenwich & the Cutty Sark (7–19K) flat · −6 m
Greenwich levels the route out, then the Cutty Sark crowd at 11 km tries to relaunch you just as the road pinches. Sit in, keep contact with your group, and bank rhythm rather than seconds.
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Tower Bridge & halfway (19–22K) +0.1%
The rise onto Tower Bridge is small; the noise is not. This is the loudest point of the day and the easiest place to throw a surge you cannot afford — cross the halfway mats on the printed split, unhurried.
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Canary Wharf & the Docklands (22–33K) flat
Miles 14–21 thread Canary Wharf, where turns, tower wind, and GPS drift conspire against pace-by-watch. Navigate by effort and the mile markers; the table's split is the target for the stretch as a whole, not for every twisty fragment.
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The City & the Embankment (33–40K) flat
From 33 km the City hands you the Embankment: flat, straight, and lined with noise. If the Blackheath restraint held, this is where London repays it — lift the effort a notch and start hunting.
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Westminster to The Mall (40–42.2K) flat
Big Ben signals the final turn, Buckingham Palace slides past, and the last 385 yards climb nothing at all on The Mall. Spend everything that is left.
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
How should I read this London split table?
As a restraint contract for the first 7 km and a licence afterwards. The plan deliberately keeps the Blackheath descent near goal effort — if your opening splits land much quicker than the printed ones, you are pre-spending the fast Embankment finish you came for.
Is the downhill start at London worth free time?
It is worth free effort, not free time. The drop off the plateau lets goal pace arrive at a lower cost, and the trap is converting that discount into a faster split. Take what the grade gives at unchanged effort and treat anything quicker as a loan against miles 14–21.
What makes the Docklands hard if they are flat?
Between roughly miles 14 and 21 the course threads Canary Wharf: sharp turns that break rhythm, wind squeezed between towers, thinner crowds after Tower Bridge's wall of noise, and high-rise GPS shadow that stops the watch telling the truth. It is a concentration problem dressed up as an easy section.
What weather does a late-April London start usually bring?
Cool and forgiving — typically around 47 °F with a dew point near 44 °F, part of why the course produces such quick times. The exceptions are real, though: 2018 hit roughly 75 °F. If the forecast runs warm, trim the goal before the start rather than negotiating with the course at 30 km.
Does running London help me get into Boston?
Only the way any certified marathon does — a London finish can be submitted toward Boston qualification. London's own Good for Age scheme is a separate system with separate standards for entry into London itself, so never treat one acceptance as implying the other.
Course split estimates use public profile information and the target you enter. Real race execution still depends on training, fueling, weather, crowding, and pacing discipline; this is planning help, not medical or coaching advice.