Route reliability record
LAS→ORD
Las Vegas to Chicago
- Flights
- 5,148
- Period
- September 2025 to August 2026
- Distance
- 1,514 mi
- Carriers
- 5
This route sits in the middle of the pack with a B. Close to three flights in four arrive on time by the DOT's definition, 2 points worse than the national rate of 77.3%. The late ones land an hour and a half behind schedule. That rests on 5,148 LAS to ORD flights, of which United Airlines flew 2,354 at 78.2% on time.
Best time to fly LAS to ORD: a 5am–8am departure, ideally on a Tuesday. Flights in that window arrived on time 87.5% of the time and Tuesday flights 82.8%, against 75.6% for the route overall.
United Airlines is the most reliable of the three carriers covered here at 78.2% on time across 2,354 flights.
Key figures
On time
75.6%
Arrivals under 15 minutes late, of 5,041 completed flights
Avg delay
88 min
Across delayed arrivals only, not all flights
Cancelled
1.24%
National rate is 1.89%
Best carrier
United
78.2% on time across 2,354 flights
These figures cover 5,148 flights between September 2025 and August 2026. Beyond the headline rate, 9.1% 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 LAS to ORD
The choice of carrier is not cosmetic here. United Airlines arrives on time 78.2% of the time; Southwest Airlines manages 67.1%. Sample sizes sit next to every figure, because a two-point gap across 551 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Spirit Airlinesthin sample | 136 | 84.8% | 66 min | 2.94% | B |
| United Airlines | 2,354 | 78.2% | 76 min | 0.34% | B+ |
| American Airlines | 1,894 | 75.2% | 114 min | 2.16% | B |
| Southwest Airlines | 551 | 67.1% | 60 min | 0.18% | C+ |
| Frontier Airlinesthin sample | 213 | 65.8% | 90 min | 4.69% | C− |
United leads Southwest by 11 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
Flight by flight
Flights on LAS 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.
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Best ways to make this trip
The most reliable ways to fly Las Vegas 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. 1 of the top 4 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. LAS → ORDLas Vegas to Chicago | United Airlines | 77.9% | 78.2% | 0.34% | 8pm–5am, Tue | UA 2102 23:59 |
| 2. LAS → MDWLas Vegas to Chicago | Southwest Airlines | 74.2% | 74.7% | 0.62% | 5am–8am, Tue (route) | — |
| 3. LAS → ORDLas Vegas to Chicago | American Airlines | 73.6% | 75.2% | 2.16% | 5am–8am, Tue | AA 2258 07:00 |
| 4. LAS → ORDLas Vegas to Chicago | Southwest Airlines | 67.0% | 67.1% | 0.18% | 8am–11am, 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 23 points, against 11 points between the best and worst carrier.
- 5am–8am762 flights87.5%
- 8am–11am1,023 flights81.4%
- 11am–2pm776 flights67.8%
- 2pm–5pm1,030 flights64.9%
- 5pm–8pm574 flights71.8%
- 8pm–5am983 flights80.0%
Scale runs 55% to 95%.
Book the early departure. Flights leaving between 5am–8am arrive on time 87.5% of the time, against 64.9% for the afternoon window. That is 23 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 1,030 flights scheduled in it.
Explore
Filter LAS 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 LAS to ORD, the best departure window is 5am–8am at 87.5% on time and the worst is 2pm–5pm at 64.9%, a wide gap of 22.6 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am87.5%
- 8–11am81.4%
- 11am–2pm67.8%
- 2–5pm64.9%
- 5–8pm71.8%
- 8pm–5am80.0%
best all US flightsScale 55% to 95%.
Across the year
When delays peak on this route
This route's year swings by 21 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 63.7% on time, 21 points below February, the best at 84.3%. 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. April was the busiest month here, with 504 flights.
Across the week, Tuesday is the strongest day at 82.8% on time and Friday the weakest at 70.0%, a spread of 13 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 108,000 reported delay minutes.
- 41%Late-arriving aircraft
- 30%Carrier
- 28%National Airspace System
- 1%Extreme weather
41% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 108,000 reported delay minutes here, that single category outweighs weather by 32 to one. The split is drawn from 108,466 reported delay minutes.
The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 87.5% on time here.
Cancellations sit at 1.24% against a national 1.89%, which is ordinary. Diversions add another 0.84%.
Connections and stage length
What a delay here actually costs
9.1% 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.
At 1,514 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.
The return leg runs 72.9% on time across 5,154 flights, within 3 points of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
The sample behind these figures is 5,148 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 calendar is the biggest lever here, not the carrier or the hour. February runs 84.3% on time and August 63.7%, a swing of 21 points. If the dates move at all, move them out of August before you think about anything else. 5,041 completed flights over 12 months sit behind that.
Common questions
LAS to ORD questions
How often is LAS to ORD delayed?
About 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 24.4% of the 5,148 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 LAS to ORD?
United Airlines leads at 78.2% on time across 2,354 flights. Southwest Airlines is at the other end on 67.1%, a gap of 11 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 LAS to ORD?
The 5am–8am departure window is the strongest at 87.5% on time. The 2pm–5pm window is the weakest at 64.9%, 23 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 LAS to ORD?
August is the weakest month at 63.7% on time, compared with 84.3% in February. Across the year that is 21 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 LAS — the return legseparate record
- Harry Reid International (LAS) delay statistics
- Chicago O'Hare International (ORD) delay statistics
- Spirit Airlines on LAS to ORD84.8%
- United Airlines on LAS to ORD78.2%
- American Airlines on LAS to ORD75.2%
- Southwest Airlines on LAS to ORD67.1%
- Frontier Airlines on LAS to ORD65.8%
- LAS to LAX, a related route77.9%
- LGA to ORD, a related route66.7%
- LAS to DEN, a related route76.5%
- Spirit Airlines on-time record84.8%
- United Airlines on-time record78.2%
- American Airlines on-time record75.2%
- Why the first flight of the morning is statistically safest
- Same route, different airline: where the carrier you pick matters most
Direction matters. LAS to ORD and ORD to LAS 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.