Route reliability record
BOS→ORD
Boston to Chicago
- Flights
- 7,860
- Period
- September 2025 to August 2026
- Distance
- 867 mi
- Carriers
- 6
This route sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 5 points worse than the national rate of 77.3%. The late ones land an hour and a half behind schedule. That rests on 7,860 BOS to ORD flights, of which Envoy Air flew 441 at 75.7% on time.
Best time to fly BOS to ORD: a 5am–8am departure, ideally on a Tuesday. Flights in that window arrived on time 87.0% of the time and Tuesday flights 75.8%, against 71.9% for the route overall.
Envoy Air is the most reliable of the six carriers covered here at 75.7% on time across 441 flights.
Key figures
On time
71.9%
Arrivals under 15 minutes late, of 7,586 completed flights
Avg delay
87 min
Across delayed arrivals only, not all flights
Cancelled
2.98%
National rate is 1.89%
Best carrier
Envoy
75.7% on time across 441 flights
These figures cover 7,860 flights between September 2025 and August 2026. Beyond the headline rate, 12.9% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Carrier by carrier
Which airline is most reliable on BOS to ORD
The choice of carrier is not cosmetic here. Envoy Air arrives on time 75.7% of the time; Delta Air Lines manages 63.7%. Sample sizes sit next to every figure, because a two-point gap across 981 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Envoy Air | 441 | 75.7% | 112 min | 3.40% | B− |
| United Airlines | 2,791 | 74.5% | 86 min | 1.79% | C |
| American Airlines | 2,165 | 73.3% | 98 min | 2.86% | C |
| Republic Airways | 930 | 71.2% | 82 min | 5.91% | C− |
| JetBlue Airways | 552 | 66.6% | 80 min | 3.26% | C− |
| Delta Air Lines | 981 | 63.7% | 75 min | 3.47% | D− |
Republic Airways cancels 5.9% of what it schedules here, the highest in the table. A cancelled flight never appears in an on-time rate, so read that column alongside the punctuality one rather than after it.
Flight by flight
Flights on BOS to ORD
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
- United 204016:2553.1% · 360 flights
- United 141406:0093.6% · 337 flights
- United 173212:3083.8% · 332 flights
- United 134909:5086.0% · 308 flights
- United 101518:2350.3% · 305 flights
- JetBlue 31107:0079.1% · 285 flights
- Delta 257007:3080.5% · 266 flights
- JetBlue 81115:3552.8% · 264 flights
- Delta 264616:1559.3% · 259 flights
Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
Best ways to make this trip
The most reliable ways to fly Boston to Chicago
Every airline on this route and on the routes between nearby airports, ranked by how often a scheduled flight actually operated and arrived on time. 2 of the top 5 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. PVD → MDWProvidence to Chicago | Southwest Airlines | 81.9% | 83.1% | 1.41% | 5am–8am, Tue | — |
| 2. PVD → ORDProvidence to Chicago | American Airlines | 76.2% | 78.9% | 3.47% | 5am–8am, Wed | — |
| 3. BOS → ORDBoston to Chicago | United Airlines | 73.2% | 74.5% | 1.79% | 5am–8am, Tue | UA 1414 06:00 |
| 4. BOS → ORDBoston to Chicago | Envoy Air | 73.1% | 75.7% | 3.40% | 11am–2pm, Mon | — |
| 5. BOS → ORDBoston to Chicago | American Airlines | 71.2% | 73.3% | 2.86% | 5am–8am, Tue | — |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 36 points, against 12 points between the best and worst carrier.
- 5am–8am1,651 flights87.0%
- 8am–11am1,400 flights84.1%
- 11am–2pm1,412 flights78.1%
- 2pm–5pm1,622 flights63.2%
- 5pm–8pm1,391 flights50.8%
- 8pm–5am384 flights51.6%
Scale runs 40% to 90%.
The 5pm–8pm window is where this operation falls apart: 50.8% on time, against 87.0% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 5am–8am window is the busiest, with 1,651 flights scheduled in it.
Explore
Filter BOS to ORD by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On BOS to ORD, the best departure window is 5am–8am at 87.0% on time and the worst is 5pm–8pm at 50.8%, a wide gap of 36.2 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am87.0%
- 8–11am84.1%
- 11am–2pm78.1%
- 2–5pm63.2%
- 5–8pm50.8%
- 8pm–5am51.6%
best all US flightsScale 40% to 95%.
Across the year
When delays peak on this route
This route's year swings by 20 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
August is the worst month at 63.1% on time, 20 points below February, the best at 83.4%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. August was the busiest month here, with 793 flights.
Across the week, Tuesday is the strongest day at 75.8% on time and Sunday the weakest at 65.8%, a spread of 10 points.
Delay causes
Why this route gets delayed
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 186,000 reported delay minutes.
- 39%Late-arriving aircraft
- 38%National Airspace System
- 20%Carrier
- 3%Extreme weather
- 0%Security
39% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 186,000 reported delay minutes here, that single category outweighs weather by 13 to one. The split is drawn from 185,883 reported delay minutes.
38% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 71,000 minutes out of 186,000, against a national NAS share of 21%.
Cancellations run at 2.98%, against 1.89% nationally. That is roughly one flight in 30 cancelled outright. A cancelled flight is invisible in every on-time figure on this page, so the punctuality numbers above describe only the flights that actually operated.
Connections and stage length
What a delay here actually costs
12.9% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection here, and two hours if the onward flight is on a separate ticket.
The 867 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty.
The return leg is a different operation and performs like one: it runs 66.6% on time across 7,864 flights, 5 points below this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 5 points of difference.
The sample behind these figures is 7,860 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.
Work out the risk of missing a connection in ORD after this flight
What to do with this
Booking this route
Put together: the delay figures matter less here than the 2.98% cancellation rate. A late arrival costs you an hour and a half; a cancelled flight costs you the day. Book the 5am–8am departure so there is still a schedule behind you if it goes wrong, and treat a same-day connection as optimistic. 7,586 completed flights over 12 months sit behind that.
Common questions
BOS to ORD questions
How often is BOS to ORD delayed?
Roughly one flight in four arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 28.1% of the 7,860 flights in this analysis, against 22.7% nationally. Delayed flights are late by an hour and a half on average.
Which airline is most reliable on BOS to ORD?
Envoy Air leads at 75.7% on time across 441 flights. Delta Air Lines is at the other end on 63.7%, a gap of 12 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on BOS to ORD?
The 5am–8am departure window is the strongest at 87.0% on time. The 5pm–8pm window is the weakest at 50.8%, 36 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are August delays on BOS to ORD?
August is the weakest month at 63.1% on time, compared with 83.4% in February. Across the year that is 20 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- ORD to BOS — the return legseparate record
- Boston Logan International (BOS) delay statistics
- Chicago O'Hare International (ORD) delay statistics
- Envoy Air on BOS to ORD75.7%
- United Airlines on BOS to ORD74.5%
- American Airlines on BOS to ORD73.3%
- Republic Airways on BOS to ORD71.2%
- JetBlue Airways on BOS to ORD66.6%
- Delta Air Lines on BOS to ORD63.7%
- BOS to DCA, a related route72.6%
- LGA to ORD, a related route66.7%
- BOS to LGA, a related route76.2%
- Envoy Air on-time record75.7%
- United Airlines on-time record74.5%
- American Airlines on-time record73.3%
- The US routes with the most cancellations
- Why the first flight of the morning is statistically safest
Direction matters. BOS to ORD and ORD to BOS are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.