Route reliability record
ORD→BOS
Chicago to Boston
- Flights
- 7,864
- Period
- September 2025 to August 2026
- Distance
- 867 mi
- Carriers
- 6
This route draws a C. About one flight in three arrives at least 15 minutes late, and the typical late arrival is a little over an hour behind schedule. Build slack into anything you connect to. That rests on 7,864 ORD to BOS flights, of which Envoy Air flew 440 at 82.7% on time.
Best time to fly ORD to BOS: a 5am–8am departure, ideally on a Saturday. Flights in that window arrived on time 86.6% of the time and Saturday flights 72.6%, against 66.6% for the route overall.
Envoy Air is the most reliable of the six carriers covered here at 82.7% on time across 440 flights.
Key figures
On time
66.6%
Arrivals under 15 minutes late, of 7,613 completed flights
Avg delay
81 min
Across delayed arrivals only, not all flights
Cancelled
2.99%
National rate is 1.89%
Best carrier
Envoy
82.7% on time across 440 flights
These figures cover 7,864 flights between September 2025 and August 2026. Beyond the headline rate, 15.6% 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 ORD to BOS
The choice of carrier is not cosmetic here. Envoy Air arrives on time 82.7% of the time; American Airlines manages 59.5%. Sample sizes sit next to every figure, because a two-point gap across 2,164 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Envoy Air | 440 | 82.7% | 67 min | 2.50% | B |
| Republic Airways | 932 | 69.7% | 79 min | 5.90% | C− |
| JetBlue Airways | 553 | 68.1% | 98 min | 3.98% | C− |
| United Airlines | 2,794 | 68.0% | 80 min | 1.79% | C |
| Delta Air Lines | 981 | 67.4% | 90 min | 3.47% | C− |
| American Airlines | 2,164 | 59.5% | 78 min | 2.91% | 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 ORD to BOS
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.
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Best ways to make this trip
The most reliable ways to fly Chicago to Boston
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. 1 of the top 5 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. ORD → BOSChicago to Boston | Envoy Air | 80.6% | 82.7% | 2.50% | 8am–11am, Thu | — |
| 2. MDW → PVDChicago to Providence | Southwest Airlines | 76.5% | 77.6% | 1.42% | 5am–8am, Wed | — |
| 3. ORD → BOSChicago to Boston | United Airlines | 66.8% | 68.0% | 1.79% | 5am–8am, Sat | UA 1693 13:55 |
| 4. ORD → BOSChicago to Boston | Republic Airways | 65.6% | 69.7% | 5.90% | 5am–8am, Tue | — |
| 5. ORD → BOSChicago to Boston | JetBlue Airways | 65.4% | 68.1% | 3.98% | 5am–8am, Wed | B6 312 10:56 |
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 32 points, against 23 points between the best and worst carrier.
- 5am–8am1,534 flights86.6%
- 8am–11am1,453 flights78.3%
- 11am–2pm1,086 flights60.2%
- 2pm–5pm1,580 flights54.1%
- 5pm–8pm1,423 flights55.7%
- 8pm–5am788 flights58.8%
Scale runs 45% to 90%.
Book the early departure. Flights leaving between 5am–8am arrive on time 86.6% of the time, against 54.1% for the afternoon window. That is 32 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 2pm–5pm window is the busiest, with 1,580 flights scheduled in it.
Explore
Filter ORD to BOS 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 ORD to BOS, the best departure window is 5am–8am at 86.6% on time and the worst is 2pm–5pm at 54.1%, a wide gap of 32.5 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am86.6%
- 8–11am78.3%
- 11am–2pm60.2%
- 2–5pm54.1%
- 5–8pm55.7%
- 8pm–5am58.8%
best all US flightsScale 45% 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.
May is the best month on the calendar at 76.6% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. August was the busiest month here, with 794 flights.
Across the week, Saturday is the strongest day at 72.6% on time and Sunday the weakest at 62.4%, a spread of 10 points.
Delay causes
Why this route gets delayed
Late-arriving aircraft accounts for 44% of the 207,000 delay minutes carriers reported here, and the remaining four split what is left.
- 44%Late-arriving aircraft
- 33%National Airspace System
- 18%Carrier
- 5%Extreme weather
- 0%Security
44% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 207,000 reported delay minutes here, that single category outweighs weather by 10 to one. The split is drawn from 206,901 reported delay minutes.
33% 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 68,000 minutes out of 207,000, against a national NAS share of 21%.
Cancellations run at 2.99%, 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
15.6% 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 71.9% on time across 7,860 flights, 5 points above 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 7,864 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 BOS after this flight
What to do with this
Booking this route
Put together: the delay figures matter less here than the 2.99% cancellation rate. A late arrival costs you a little over an hour; 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. 7,613 completed flights over 12 months sit behind that.
Common questions
ORD to BOS questions
How often is ORD to BOS delayed?
About one flight in three arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 33.4% of the 7,864 flights in this analysis, against 22.7% nationally. Delayed flights are late by a little over an hour on average.
Which airline is most reliable on ORD to BOS?
Envoy Air leads at 82.7% on time across 440 flights. American Airlines is at the other end on 59.5%, a gap of 23 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 ORD to BOS?
The 5am–8am departure window is the strongest at 86.6% on time. The 2pm–5pm window is the weakest at 54.1%, 32 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 September delays on ORD to BOS?
September is the weakest month at 56.2% on time, compared with 76.6% in May. 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
- BOS to ORD — the return legseparate record
- Chicago O'Hare International (ORD) delay statistics
- Boston Logan International (BOS) delay statistics
- Envoy Air on ORD to BOS82.7%
- Republic Airways on ORD to BOS69.7%
- JetBlue Airways on ORD to BOS68.1%
- United Airlines on ORD to BOS68.0%
- Delta Air Lines on ORD to BOS67.4%
- American Airlines on ORD to BOS59.5%
- ORD to LGA, a related route66.6%
- DCA to BOS, a related route70.1%
- ORD to LAX, a related route72.0%
- Envoy Air on-time record82.7%
- Republic Airways on-time record69.7%
- JetBlue Airways on-time record68.1%
- The US routes with the most cancellations
- Why the first flight of the morning is statistically safest
Direction matters. ORD to BOS and BOS to ORD 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.