Chicago Marathon Training Plan: 16 to 18 Weeks, Built for You

Chicago Marathon Training Plan: 16 to 18 Weeks, Built for You

A free AI training plan for the Bank of America Chicago Marathon on Sunday, October 11, 2026 — even-split pacing, heat readiness, and paces set from your own fitness.

Build my Chicago plan

The Bank of America Chicago Marathon runs Sunday, October 11, 2026. It is the flattest and fastest of the six Abbott World Marathon Majors: start and finish in Grant Park, 26.2 miles through 29 neighborhoods, and a course quick enough that Kelvin Kiptum ran 2:00:35 here in 2023 — the world record at the time. Around 50,000 runners finish every year, carried by crowds that barely let up from Lincoln Park through Pilsen and Chinatown. But flat does not mean easy. With no hills to throttle you, nothing stops you from going out too hot in the first 10 miles, and that is exactly where most Chicago marathons are lost. Even splits are the number one skill on this course. Add an October forecast that can hand you 40°F or 80°F, wind coming off Lake Michigan, and Loop skyscrapers that scramble your GPS for the first few miles, and Chicago becomes a race of execution rather than raw strength. This RunRun plan covers 16 to 18 weeks and adapts to what you are actually chasing — your first marathon, sub-4:00 (9:09 per mile, roughly 5:41 per kilometer), sub-3:30, or a Boston Qualifier — with every pace derived from your VO2max or a recent race result. Race details and start waves: /en/runs/marathon-de-chicago-2026.

Why choose RunRun?

16 to 18 weeks, counted back from October 11

Enter your race date and the days you can train, and RunRun builds the full block backward from race day: 4 to 5 weeks of aerobic base, a threshold and marathon-pace development phase, peak load weeks, then a 3-week taper. The plan is rebuilt every week around the sessions you actually ran, not the ones the template assumed you would run.

One plan per goal, from first marathon to BQ

Finishing your first marathon, breaking 4:00 (9:09 per mile), breaking 3:30 (8:00 per mile), or chasing a Boston Qualifier are four different builds. Weekly mileage, the number of quality sessions, and the length of your marathon-pace blocks all change. RunRun calibrates every workout to your specific goal time instead of handing you a one-size-fits-all program.

Even-split pacing built into the training

Chicago is dead flat, which means the course never protects you from your own pacing mistakes. The plan builds in progressive long runs and marathon-pace blocks of 5 to 12 miles at your exact goal pace, so holding a steady rhythm becomes automatic instead of something you have to police on your watch every thirty seconds.

Threshold work, VO2max intervals, and fast finishes

1K repeats and 95% VO2max blocks to raise your aerobic ceiling, 2×20-minute threshold runs to push back the point where lactate accumulates, and long runs finished at marathon pace to teach your legs to produce speed on tired muscles — the exact skill that decides your final 5 miles up Michigan Avenue.

Ready for whatever October gives you

Chicago in October can mean 40°F at the gun or 80°F by late morning. The plan includes heat-acclimation runs in the final weeks, a fueling strategy rehearsed on every long run, and a simple adjustment rule: expect to run roughly 2 to 3% slower for every 10°F above 60°F, and plan your goal pace accordingly the night before.

Strava synced, workouts pushed to Garmin

Connect Strava to match your runs to your planned sessions automatically and track pace deviation and weekly load. Export workouts to Garmin Connect in one click and run with the structure on your wrist. Heart rate zones are calculated with the Karvonen formula from your resting and maximum heart rate.

Chicago Marathon plan overview (18-week build)

W1

Week 1 — Aerobic base and pace calibration

A setup week with no hard running. The goal is to lock in your reference paces from your VO2max or a recent 10K or half marathon. RunRun derives your five training paces — easy, marathon, threshold, VO2max, recovery — plus your Karvonen heart rate zones. Starting mileage is set from what you have actually run in the last 8 weeks, never from a textbook curve.

  • •Easy run 45 min in zone 2 (conversational pace)
  • •Easy run 50 min + 6 × 20-second strides
  • •Long run 8 miles easy — weekly volume: 25 to 30 miles
W6

Week 6 — Threshold work begins

The development block opens. Your first structured threshold session lands alongside the first marathon-pace segment at the end of a long run. This is where your body starts to recognize the rhythm you will hold on Michigan Avenue. On a flat course like Chicago, that pace memory is worth more than any amount of hill work.

  • •20 min warm-up + 2 × 20 min at threshold pace (5 min jog recovery)
  • •Easy run 50 min in zone 2 + form drills
  • •Long run 12 miles, last 20 min at marathon pace — weekly volume: 35 to 40 miles
W13

Week 13 — Peak load and the dress rehearsal

The biggest week of the cycle. Your long run reaches 20 miles with an extended goal-pace block, run as close to race conditions as you can get: same start time, same breakfast, same gels, same shoes. After this week the volume only comes down.

  • •20 min warm-up + 3 × 2K at threshold pace (3 min recovery)
  • •Easy run 45 min in zone 2, strictly easy
  • •Long run 20 miles with the final 7 miles at marathon pace — weekly volume: 45 to 50 miles
W18

Week 18 — Final taper and race day

Volume drops roughly 60% from peak while intensity stays, delivered in very short doses to keep the legs sharp. A last touch-up session Wednesday, full rest Friday, a short shakeout Saturday. Then Sunday, October 11: your corral, Grant Park, and a pace plan you have already run twenty times in training.

  • •Easy run 35 min + 4 × 2 min at marathon pace (2 min recovery)
  • •Full rest or an easy walk
  • •Day before: 20 min very easy shakeout + 3 strides — the work is done

Chicago-specific race strategy

1

Run even splits — the first 10K should feel boring

Nothing on this course slows you down early. The Grant Park crowd, the drop under Columbus Drive, and pure adrenaline will put you 10 to 15 seconds per mile ahead of plan before you notice it. The target is simple: cover the second half in the same time as the first, or faster. That means the opening 3 miles should feel almost too easy. Rehearse it on every marathon-pace long run rather than hoping you will find the discipline on race day.

2

Do not trust your GPS through the Loop

Skyscrapers in the Loop and River North bounce the satellite signal. Between mile 1 and mile 4 your watch can show a pace 20 to 30 seconds per mile off the truth, and the cumulative distance error follows you for the rest of the race. Take manual splits at the official mile markers, run by the effort you programmed rather than by instantaneous pace, and expect to finish reading 26.4 or 26.5 miles on your watch. That is normal, not a course measurement error.

3

Have two race plans ready for the forecast

October in Chicago spans an enormous range: some editions have gone off around 40°F, others have climbed past 80°F. If summer allows, get 6 to 8 heat-acclimation runs in over the final six weeks, and set a numeric plan B in advance — above 60°F, add roughly 2 to 3% to your goal pace for every 10°F. Wind off Lake Michigan on the northern and southern stretches costs a few more seconds per mile, so tuck into a group when you can rather than pushing the effort to hold the number.

4

Rehearse the last 5 miles up Michigan Avenue

After Chinatown the course turns north onto Michigan Avenue: a long, straight, exposed stretch with thinner crowds in places and no terrain change to break the effort into pieces. This is where race plans come apart. Finish at least four of your long runs with 5 to 8 miles at exact goal pace on flat, straight roads so the pattern is automatic. The only real climb of the day is the short ramp up Roosevelt Road at mile 26, right before the final turn to the finish — know it is coming and leave a few seconds in the tank for it.

5

Lock in fueling from your very first long run

Running somewhere between 3:30 and 4:30, you need 60 to 90 grams of carbohydrate per hour after the first hour. That is a trainable skill: start taking a gel every 35 to 45 minutes on runs of 90 minutes or more, and test the on-course sports drink well in advance so you can decide whether to use the aid stations or carry your own. Chicago aid stations are frequent and well staffed, but a product you have never tried in training is still the single biggest cause of race-day stomach trouble.

landing.faq

How many weeks should I train for the Chicago Marathon?
Sixteen weeks if you are already running 25 to 30 miles per week consistently, 18 weeks if you are building from a smaller base or running your first marathon. Below 12 weeks the threshold development phase gets compressed and injury risk climbs sharply. For the October 11, 2026 race, an 18-week build starts in early June and a 16-week build starts in late June. RunRun works with whatever runway you have and redistributes the phases accordingly, flagging it clearly if the timeline is too short for the goal you entered.
How many miles per week do I need to run?
To finish your first marathon: 25 to 35 miles per week peaking around 40. To break 4:00: 30 to 40 miles peaking near 47. To break 3:30: 40 to 50 miles peaking around 55. To chase a Boston Qualifier: 50 to 70 miles. Distribution matters as much as the total — roughly 80% of your volume easy and 20% hard, following the polarized model described by Stephen Seiler. Build by no more than about 10% per week and take a down week every third or fourth week.
How do I get into the Chicago Marathon?
There are three main routes. The drawing, which typically opens in the fall of the prior year with results announced a few weeks later. A time qualifier, which guarantees entry if you have run a marathon or half marathon under the standard for your age group and gender inside the eligibility window. And charity entries, which require a fundraising commitment but stay available later in the year once the drawing has closed. Exact dates and qualifying standards change from edition to edition, so confirm them on chicagomarathon.com before you set your training calendar.
What is the weather like on Chicago Marathon race day?
A typical mid-October morning start sits somewhere around 45 to 55°F, close to ideal marathon weather. The historical range is much wider: some editions have run near 40°F, others well above 80°F. Wind off Lake Michigan is the other variable, most noticeable on the northern and southern portions of the course. Prepare two outfits and two pace plans, then commit the night before based on the forecast. Bring a throwaway layer for the wait in your Grant Park corral — mornings there are colder than the daytime high suggests.
When should I do my last 20-mile long run?
Your longest run — 20 miles for most runners, 22 at the outside for experienced, faster athletes — belongs three weeks out, which puts it around September 20, 2026. Follow it with a 15-mile long run, then a 10-mile long run in race week minus one. A long run inside two weeks of race day gives you no physiological return: adaptations take 10 to 14 days to show up as fitness, and the residual fatigue will still be in your legs on the start line.
What pace do I need to break 4:00 at Chicago?
Sub-4:00 means holding 9:09 per mile for the full 26.2 miles. Train at 9:05 per mile to build a small cushion and aim to come through halfway around 1:59:00. The honest prerequisite is being able to run a half marathon around 1:52, or a 10K around 51 minutes, within the two months before race day. On a flat course like Chicago that pace has to stay level from the gun to the finish — steady execution is the whole difference between 3:58 and 4:07.
The course is flat — should I expect a PR?
Chicago is statistically one of the fastest marathons in the world, with almost no elevation change and a single genuine rise, the Roosevelt Road ramp at mile 26. It is excellent PR terrain, with two conditions. First, the weather: above 70°F the advantage of the flat profile evaporates. Second, pacing discipline: on a course that never slows you down, going out 10 seconds per mile too fast gets paid back in full after mile 20. Flat rewards preparation, and it is completely unforgiving of improvisation.
Where can I find a free Chicago Marathon training plan?
RunRun generates a personalized plan free when you sign up. Enter the October 11, 2026 race date, your goal time, your available days, and your current fitness, and the plan is built for you rather than downloaded as a static PDF. Paces come from your VO2max or a recent race result, heart rate zones use the Karvonen formula, and the plan is recalculated every week from the sessions you actually completed. You can connect Strava and export workouts to Garmin Connect. Other Illinois races are listed at /en/runs/us/illinois.

Build your 2026 Chicago Marathon plan

Tell RunRun your goal time, your available training days, and your current fitness. You get a 16-to-18-week plan counted back from October 11, 2026, with paces set from your own numbers. Free, synced with Strava, exportable to Garmin.

Build my Chicago plan