How we build and check our travel tools

Our carry-on checker and airline comparisons cover 81 airlines, the bag fee calculator 44, our connection-time guides 56 airports and our airport guides 112, and our plug adapter finder covers 228 countries and territories. They're researched and maintained by Steven Mo at Good Flight Deals. Here's exactly where the numbers come from and how we keep them current.

Carry-on and personal item sizes

• We start from each airline's official baggage policy, linked on every airline page.
• We cross-check every figure against recent independent sources (including Upgraded Points' carry-on chart) and news coverage of policy changes, such as the spring 2026 checked-bag fee increases.
• When sources disagree, we use the more conservative number and say so on the page (for example Allegiant's personal item), so you don't get caught at the gate.
• Sizes are shown in the unit the airline publishes, with a conversion. U.S. airlines measure wheels and handles as part of the bag.
• "Included on the cheapest fare" means the lowest fare you can buy on the airline's own site includes a full-size carry-on. Where it depends on the route, we say which routes.

Checked bag fees

• For each of the 44 airlines we record the published price of the first, second and third checked bag on the route most of our readers fly with it: domestic flights for U.S. airlines, flights to and from the U.S. for international ones, and flights within Europe for European budget airlines.
• We start from the airline's own baggage page and its announcements (such as American's April 2026 fee release), then check every figure against recent independent coverage, because many airline sites block automated access or load prices only after you search. Each airline page lists what we checked it against, with dates.
• "Paid online" is the price when you pay ahead on the airline's site or app; "at the airport" is the price at check-in. "Regular economy" is the fare most travelers buy (Main Cabin, Economy Classic, Economy Saver), not a bundle; "cheapest fare" is basic economy or its equivalent.
• Airlines that price bags by route or date get a range, not a single number, and Volaris' published maximums are labeled as such. When an airline doesn't publish a price, we say "not published" rather than guess.
• Prices in other currencies are converted to U.S. dollars at European Central Bank reference rates from 2026-10-16, rounded to the dollar.

Airline comparisons

• Bag rules and fees come from the same data as the carry-on and bag fee pages. We only mark a bag-fee winner between airlines in the same market, since a domestic fee and a long-haul allowance aren't comparable.
• On-time and cancellation rates are 2025 full-year figures from the U.S. Department of Transportation's Bureau of Transportation Statistics, for each airline's own flights (regional partners are reported separately). Airlines too small to report aren't rated.
• Legroom is typical standard-economy seat pitch; Wi-Fi reflects each airline's policy as of our last check.
• We mark a winner in a category only when the difference is real (for example a bigger bag allowance or a cheaper first checked bag). We don't declare an overall winner: what's better depends on your route and what you value.

Recommended layover times

Airlines' official minimum connection times are filed in industry systems and aren't published, and they assume everything runs on time. Instead, we add up the steps a connection takes at each airport, using its layout (which terminals connect inside security, how you get between them, where customs is) and these allowances:

• Getting off the plane and walking to the next gate: 15–25 min, depending on the airport's size
• Changing terminals: The airport's own transfer time (train, bus or walk), typically 5–25 min
• Security again after a terminal change outside security: 30 min in the U.S. (15 with PreCheck), 20 min elsewhere
• U.S. immigration and customs: 35 min (15 with Global Entry); 30 min at other first ports of entry
• Collecting and rechecking bags after customs: 20 min
• TSA again after customs: 20 min (10 with PreCheck)
• Passport control at hubs like Paris or Frankfurt: 20 min
• Transfer security at hubs that screen connecting passengers: 20 min
• U.S. preclearance before a U.S.-bound flight: 45 min (30 with Global Entry)
• Separate tickets: 60 min with checked bags, 30 min without
• Reaching the gate before boarding closes: 15 min
• Buffer for a small delay: 15 min domestic, 30 min when crossing a border

We round the total up to the next 5 minutes. The "comfortable" time adds 30 minutes (45 when you cross a border or self-transfer). Try your own connection with the layover calculator.

Airport guides

• Transit options, journey times and fares come from the operators (linked on every guide) and are rounded and labeled approximate, since fares change. Taxi prices are typical ranges or the official flat fare where one exists.
• We list established lounges and hotels inside or connected to the terminals, not every pay-in lounge.
• Parking lists each U.S. airport's official options from cheapest to closest. Most airports now price parking by demand, so we link to live rates and only show a price where the airport publishes a daily maximum.
• "Leave on a layover" adds the time to get out of the airport (20 minutes in the U.S., 45 with passport control abroad), the fastest round trip into town, an hour there and the time to get back through security to the gate (1 hour in the U.S., 1½ hours abroad), rounded up to the half hour.

Airlines at each airport and airport rankings

• Airport guides cover every airport we send cheap flight alerts from. The airlines listed at each airport are the ones we have pages for with regular service there, checked against the airport's own airline list and its Wikipedia "Airlines and destinations" table; regional brands count as their mainline airline (United Express as United). It isn't a complete list.
• Connection-time guides cover 56 hubs and focus cities where travelers actually connect; smaller airports get an airport guide instead.
• Airport rankings are computed from the same guide and connection data, so a ranking always matches the guide it links to.

Guides

• Basic economy guides take bag rules from our airline data and seats, boarding, changes and miles from each airline's fare rules and recent coverage of changes, with the sources on each page. Where a rule isn't published or sources disagree, we leave it out rather than guess.
• Airline rankings compare U.S. airlines only, where we have like-for-like data (U.S. DOT on-time figures, legroom, Wi-Fi policy and domestic bag fees). Equal values share a rank.
• Bag size pages run the same fit check as the carry-on checker against every airline's published limit, turning the bag whichever way fits best.
• Passenger rights guides summarize the official regulations (linked on each page) and say what's pending, such as the 2026 EU261 reform. They're not legal advice.
• Flight search comparisons describe documented features only; we leave out add-on prices, which change constantly. We aren't affiliated with any of these sites.

Plug types and voltage

• Plug types, voltage and frequency for 228 countries and territories follow the International Electrotechnical Commission's World Plugs list, as compiled on Wikipedia. Where a country uses two voltages, we show both.
• Adapter advice uses which plugs physically fit which sockets: for example a two-pin Type C plug also fits Type E, F, H, J, K, L and N sockets, which is why one Type C adapter covers most of continental Europe.
• Voltage advice compares 100–130 V countries with 220–240 V countries; it can't know your device, so check its label.

Research and widgets

• Our data studies are computed from the same datasets as the tools, so a study, its CSV download and the tool pages always agree. You're welcome to use the data with a link to the study.
• Our embeddable widgets show the same data as the tool pages and carry no ads, cookies or analytics.

How often we check

We review the full dataset at least every quarter and whenever an airline announces a change. Each page shows the date we last verified it, currently Oct 17, 2026.

About the author

Steven Mo researches and maintains the data behind Good Flight Deals' travel tools and studies, checking every figure against the sources listed on each page and updating them when airlines and airports change their rules. Every rule change we apply is recorded, with its source, in our changes log.

Corrections

Spotted something out of date? Email hello@goodflightdeals.com with the page and what's changed. We check every report against the airline or airport's own information and update the page.

Changelog

• Oct 20, 2026: added carry-on rules for 37 more airlines (81 in all), airport guides for every airport we send deals from (112 in all, 56 with connection guides), airport rankings, basic economy guides, airline rankings, bag size pages, passenger rights guides, flight search comparisons and a changes log. Updated Lufthansa and SWISS for Economy Basic on every European route, and JetBlue for its new fare names.
• Oct 17, 2026: added checked bag fees for 44 airlines, airport guides for 43 airports, plug types for 228 countries, three data studies and embeddable widgets.
• Oct 17, 2026: launched with 44 airlines and 43 airports. Spirit Airlines isn't listed because it stopped flying on May 2, 2026. Checked-bag fees reflect the spring 2026 increases at United, Delta, Southwest, American, Alaska and JetBlue.

See all free tools or get cheap flight alerts from your home airport.