These three free engines power most flight searches on the internet, and people constantly ask which one is "cheapest." The honest answer: they pull from overlapping data, so on a given route they often show the same fare. The differences are in the features that help you find the cheap fare faster - and in what each one quietly leaves out.
Quick verdict
| Google Flights | Skyscanner | Kayak | |
|---|---|---|---|
| Best at | Calendar & Explore map | Budget carriers & "Everywhere" | Filters & price forecast |
| Budget airline coverage | Partial | Widest | Good |
| Flexible-destination search | Explore map | Everywhere search | Limited |
| Price prediction | Yes (low/typical/high) | Basic | Yes (forecast) |
| Hidden-city fares | No | No | No |
| Cost | Free | Free | Free |
Google Flights: the best scout
Google Flights is the fastest, cleanest interface and has the most useful planning tools: the date grid and price calendar that reveal the cheapest days to fly at a glance, and the Explore map for flexible destinations. Its weak spots: it omits some ultra-low-cost carriers and never shows hidden-city itineraries. Use it first to understand the price landscape - the full feature list is in our Google Flights tricks guide.
Skyscanner: the widest net
Skyscanner's edge is coverage and flexibility. It tends to include more budget and regional carriers than Google, and its "Everywhere" search - type your origin, destination "Everywhere," and see the cheapest countries and cities - is the single best tool for travelers who'll go wherever is cheap. If a fare exists on an obscure low-cost airline, Skyscanner is the most likely of the three to surface it.
Kayak: the power user's filters
Kayak's strength is control. Its filters are the most granular (cabin, stops, specific airports, flight quality, even "no red-eye"), and its price forecast gives a buy-or-wait recommendation. It also monitors a fare after you find it. If you know exactly what you want and need to slice a busy route down to the right option, Kayak does it best.
The catch all three share
None of these engines shows hidden-city/skiplagging fares or most split-ticket combinations, and each omits some carriers. So the cheapest fare for your route can be invisible to all three at once. That's the case for cross-checking: after scouting with Google and Skyscanner, compare against tools that catch those fare types. Our flight finder tool comparison covers Aviasales (agency fares Google skips) and Kiwi (hidden-city and virtual-interline routings) - the two that most often beat the big three.
Don't pick one - compare them all
FareFinderAI runs your route across multiple engines at once, including the budget carriers and hidden-city fares Google, Skyscanner, and Kayak miss. Free, no account.
Search All Engines Free →So which should you use?
- Flexible on dates? Google Flights' calendar.
- Flexible on destination? Skyscanner's Everywhere search.
- Fixed route, want the perfect option? Kayak's filters.
- Want the genuine lowest fare? Scout with one or two of these, then cross-check a tool that shows hidden-city and budget fares before you book.
Frequently asked questions
Bottom line: these three are excellent scouts but imperfect finishers. Search with them, then cross-check - that combination is what actually lands the lowest fare.