# Southwest left a quarter of its domestic seats empty in 2025

Published 2026-11-07 · By Pushbuild · Data: [Airline Route Traffic API – US Passengers, Seats and Cargo by Route](https://pushbuild.com/apis/airline-route-traffic.html)

**Southwest filled 74.3% of its domestic seats in 2025, the lowest of any large US airline; Delta filled 82.7%.**

“TranStats provides one-stop shopping for intermodal transportation data for researchers, decision-makers, as well as the general public interested in transportation issues.”

— [Bureau of Transportation Statistics, T-100 Segment (All Carriers)](https://www.transtats.bts.gov/Fields.asp?gnoyr_VQ=FMG)

| Airline | Passengers | Seats | Seats filled |
| --- | --- | --- | --- |
| Southwest Airlines Co. | 165,845,814 | 223,187,191 | 74.3% |
| Breeze Aviation Group DBA Breeze | 6,272,898 | 8,375,590 | 74.9% |
| SkyWest Airlines Inc. | 44,096,742 | 57,034,891 | 77.3% |
| Spirit Air Lines | 28,668,063 | 36,990,211 | 77.5% |
| Republic Airline | 19,552,803 | 25,197,149 | 77.6% |
| Frontier Airlines Inc. | 31,685,561 | 40,680,704 | 77.9% |
| Endeavor Air Inc. | 14,015,556 | 17,611,827 | 79.6% |
| PSA Airlines Inc. | 13,621,931 | 17,073,768 | 79.8% |
| Alaska Airlines Inc. | 33,200,065 | 41,415,680 | 80.2% |
| JetBlue Airways | 28,565,492 | 35,353,521 | 80.8% |
| Hawaiian Airlines Inc. | 10,589,608 | 13,058,662 | 81.1% |
| Envoy Air | 17,396,140 | 21,435,404 | 81.2% |
| Horizon Air | 5,979,154 | 7,348,440 | 81.4% |
| American Airlines Inc. | 132,093,389 | 162,172,404 | 81.5% |
| Allegiant Air | 18,824,033 | 23,106,734 | 81.5% |
| United Air Lines Inc. | 109,998,660 | 135,035,880 | 81.5% |
| Delta Air Lines Inc. | 138,819,819 | 167,948,190 | 82.7% |
| Piedmont Airlines | 6,046,494 | 7,248,386 | 83.4% |

## Caveats

Domestic segments, carriers with 5M+ passengers. Load factor by seats, not miles.

## Sources

- [Bureau of Transportation Statistics, T-100 Segment (All Carriers)](https://www.transtats.bts.gov/Fields.asp?gnoyr_VQ=FMG), read through the Pushbuild [Airline Route Traffic API](https://pushbuild.com/apis/airline-route-traffic.html) on 2026-11-07

Data as of 2026-11-07. Every figure in this post is in the table above and the CSV below.

Download the data behind this post: [b4-t100-load-factor-by-carrier-2025.csv](https://pushbuild.com/apis/analysis/data/b4-t100-load-factor-by-carrier-2025.csv)

## Get this data

Every number in this post comes from the [Airline Route Traffic API – US Passengers, Seats and Cargo by Route](https://pushbuild.com/apis/airline-route-traffic.html). $0.0008 per row returned; every key gets $1 of free usage each month.

```
curl -X POST https://api.pushbuild.com/airline-route-traffic/run \
  -H "X-API-Key: YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{"airports": ["BOS"], "maxItems": 20}'
```

[API docs and key](https://pushbuild.com/apis/airline-route-traffic.html)[More analysis from this data](https://pushbuild.com/apis/analysis/api/airline-route-traffic/)Embed this chart

Free to reuse with the credit link. Paste this HTML into your page, or use the [SVG file](https://pushbuild.com/apis/analysis/airline-load-factor-2025/chart.svg).

Want a table like this in Google Sheets, refreshed on demand? Free script: [copy a web table into Google Sheets](https://pushbuild.com/free/scripts/website-table-to-sheets/).

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Header photo: [Alf van Beem](https://commons.wikimedia.org/wiki/File:D-AIPZ_Lufthansa_Airbus_A320-211_takeoff_from_Schiphol_runway_36C_pic1.JPG), Public domain, via Wikimedia Commons.

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As of 2026-11-07. Source: https://pushbuild.com/apis/analysis/airline-load-factor-2025/