London vs Chicago Marathon — Spectacle vs Speed

London's Tower Bridge pageant and record 1.33M ballot vs Chicago's pan-flat PB machine and easier entry. Compare odds, course and which Major to run.

Quick Comparison

Feature 2027 TCS London Marathon - Apr 25 2026 Chicago Marathon - Oct 11
Country/RegionUKUSA
MonthAprilOctober
Avg Temperature8-14°C10-16°C
Course TypeFlatFlat
Elevation~30m~15m
Field Size56,00054,000
EntryLottery/CharityLottery/Time
World MajorYesYes
BQ CourseYesYes
Crowd SupportExcellentExcellent

Detailed Comparison

Course feel: a downhill spectacle vs a pan-flat metronome

Both are fast, but they get there differently. London is net downhill — roughly 127m of gain against 161m of loss — and the drop off Blackheath in the opening miles is so generous that the real danger is going out too hard before Cutty Sark at mile 6. The course narrows and surges through Greenwich, hits a short climb up to Tower Bridge near halfway (where the noise is loudest you'll hear all day), then funnels along the Embankment to a finish on The Mall beside Buckingham Palace. Chicago is the flatter of the two on paper — a pan-flat loop (~20m of total relief) through 29 neighborhoods on wide grid streets, with one cruel little rise onto Roosevelt in the final 400m before Grant Park. Chicago feels like a metronome; London feels like a parade you happen to be running in.

The practical upshot: London's early downhill flatters your watch and punishes your quads late, so bank nothing in the first 10K. Chicago gives you no hills to blame, which is exactly why a bad day there feels so exposed.

Entry: the world's hardest ballot vs the easiest Major to secure

This is the sharpest split between them. London is now the most over-subscribed marathon on earth: a record 1.33 million people entered the ballot for 2027 (up from 1.13 million for 2026), pushing general-ballot odds to roughly 1.3%. Realistic routes in are Good For Age (London's own time standard), a Championship place, or — by far the most common — a charity place that asks you to fundraise a few thousand pounds. Chicago is widely called the easiest Major to secure: its drawing pulls from a smaller pool (160,000+ applicants), and on top of the lottery there are time-qualifier, multi-year legacy, charity and international tour-operator entries. If you simply want a Major bib without a multi-year wait, Chicago is the pragmatic answer; London is the one you keep entering and hoping for.

Weather: a temperate April vs the warmest Major

London runs in late April at a forgiving 8-14C — the single biggest reason average runners PB there. Chicago goes in mid-October (10-18C) and is, on average, the warmest of the Majors; its 2007 edition was famously halted mid-race in ~88F heat, and Lake Michigan can throw cold crosswinds or a sudden warm spell on the same calendar date. London's weather is the reliable variable; Chicago's is the gamble. Plan your kit either way with What to Wear, and use the Race Time Predictor to set a sane target before you toe either line.

Travel, history and what each finish means

For an international runner, Chicago is the simpler trip — one US city, one flat course, no transit puzzle — while London rewards you with a long weekend in one of the world's great cities. The pedigree differs too: London now holds the men's marathon world record after Sabastian Sawe ran around 1:59:30 there in April 2026, cementing its status as where the sport's fastest times are chased in spring. Chicago carries its own history — Kelvin Kiptum ran 2:00:35 here in 2023, long among the fastest marathons ever recorded — but that mark is historical, not the current record. Both finishes are iconic; only one ends with you running up The Mall toward the palace.

Who should pick which

If you are a PB or Boston-qualifying chaser who wants the surest fast conditions, London's cool April and net-downhill profile edge it — provided you can get in; if you can't, Chicago's flat October course is the reliable fallback and you can verify your target with the Boston Qualifying Calculator. If you are a Six Star collector who just needs the medal without a multi-year ballot saga, run Chicago and save London for when (or if) the ballot finally smiles on you. If you are a first-time Major runner chasing pure atmosphere, London's million-strong crowds and landmark-after-landmark route are unmatched theater. Build the buildup for either with a structured training plan and use a pace calculator to lock your splits.

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Frequently Asked Questions

Is London or Chicago Marathon faster for a PB?

Both are among the fastest Majors. Chicago is the flatter course (~20m of total relief) on its pan-flat grid-street loop, but London is net downhill (about 127m gain vs 161m loss) and runs in cooler April weather, which is why many average runners PB there. The deciding factor is usually weather, not gradient — Chicago's October day can be warm, while London's April is reliably temperate. Set a realistic target for either with our Race Time Predictor.

How hard is it to get into the London Marathon vs Chicago?

London is far harder. A record 1.33 million people entered the 2027 ballot, pushing general-ballot odds to roughly 1.3%. Realistic routes are Good For Age, a Championship place, or a charity place with a fundraising commitment. Chicago is widely considered the easiest Major to secure: its drawing draws from a smaller pool (160,000+ applicants), plus time-qualifier, legacy, charity and tour-operator entries. For a bib without a multi-year wait, Chicago is the pragmatic pick.

Is the London Marathon flat compared to Chicago?

Chicago is the flatter of the two — essentially pan-flat with only about 20m of total relief and one short rise to the Grant Park finish. London is net downhill rather than truly flat: a steep early drop off Blackheath, a relatively flat middle past Cutty Sark, a short climb to Tower Bridge near halfway, then a fast run-in to The Mall. London's early downhill tempts runners into going out too fast, so don't bank time before 10K.

Can I qualify for Boston at the London or Chicago Marathon?

Yes — both are certified Boston-qualifying courses, and both are popular BQ destinations thanks to their flat-to-downhill profiles and large pace groups. London's cool April weather and net-downhill course make it an excellent BQ attempt if you can secure entry; Chicago's flat October loop is the reliable US alternative. Check your exact cutoff with the Boston Qualifying Calculator, then plan your splits with our Pace Calculator.

What is the weather like at London vs Chicago Marathon?

London runs in late April at a temperate 8-14C, which is a big reason it's such a strong PB race. Chicago goes in mid-October at 10-18C and is, on average, the warmest of the Majors — its 2007 race was halted mid-event in roughly 88F heat, and Lake Michigan can deliver cold crosswinds or warm spells on the same date. London's weather is the dependable variable; Chicago's is the gamble. Pack accordingly with our What to Wear tool.

Which has a better atmosphere, the London or Chicago Marathon?

It depends on what you want. London delivers wall-to-wall theater — roughly a million spectators, the world's largest charity-running community, and a landmark-after-landmark route past Cutty Sark, Tower Bridge and The Mall. Chicago's energy shifts neighborhood by neighborhood across its 29 districts, with a famously loud Grant Park finish. London wins on grandeur and crowd density; Chicago wins on a steady, all-day roar and an easier overall race-day experience.

Should I run the London or Chicago Marathon first for Six Stars?

If you're collecting the Six Star medal and want to lock in a Major without a multi-year ballot saga, run Chicago first — it's the easiest Major to secure and a friendly course. Save London for whenever the ballot finally comes through, or pursue Good For Age, a Championship place or a charity slot if you'd rather not wait. Sequencing usually comes down to which entry you can actually get, not which is the harder course.

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