We ran the exact same search on Google Flights, Skyscanner, Kayak, Momondo and Kiwi.com using the same dates, currency and location. This time the result surprised us. Here's what we found.
This route flipped the script: Google Flights was the cheapest, not the priciest. It found the lowest protected fare (Aer Lingus via Dublin, €495) and the cheapest nonstop (€650). Skyscanner and Kayak were only a few euro behind on the 1-stop; Kiwi.com was the priciest. The cheapest fare of all was a €473 self-transfer (Ryanair + SAS, two stops, ~32 hours), but it barely undercuts the clean Aer Lingus ticket. Prices change constantly, so treat this as a snapshot, not a permanent ranking.
Ranked by the cheapest protected connection, the safest fare to book. The badge under each tool shows how you book with it. Every term is explained under the table.
| Rank | Tool | Cheapest direct | Cheapest protected connection | Cheapest self-transfer |
|---|---|---|---|---|
| 1 | Comparison site | €650 | €495 | €487 |
| 2 | Comparison site | €669 | €507 | €487 |
| 3 | Comparison site | €678 | €508 | €473 |
| 4 | Comparison site | €678 | €508 | €473 |
| 5 | Reseller | €719 | €546 | None cheaper here |
All legs on one ticket, so the airline rebooks you free if a connection is missed. The safest fare to book.
Separate tickets you stitch together (the tool's own label, not ours). Often cheaper, but a missed leg is on you unless a guarantee covers it.
A comparison site shows the fares and sends you to the airline or an agency to pay. A reseller like Kiwi.com takes your payment itself and adds its own fees, so it usually costs a little more.
Why the prices differ: they all list third-party agencies (you'll spot Trip.com and Kiwi in Google's own booking options too), so it isn't about who shows agencies. On this competitive transatlantic route they were all within a few euro on the same Aer Lingus fare, and Google happened to price it lowest (€495) and the nonstop lowest too. The self-transfer (Ryanair + SAS) was a touch cheaper still, but far longer. Skyscanner has the widest low-cost-carrier coverage.
A cheaper agency price isn't always the better deal. When we searched again the prices held, but a third party can still raise the fare, or even cancel it, before you've paid. Some show the price without a checked bag, or add a surcharge for certain payment methods, so the number you click isn't always the number you pay. On Skyscanner you can see each agency's rating: if it's low, it's often worth a few euro more for a better-rated one, or better still, booking straight with the airline.
Kayak and Momondo are owned by the same company and, as expected, returned the same fares; we list both because people search for each. Kiwi.com is essentially a third-party reseller: it showed the same flights but priced highest across the board (protected €546, nonstop €719), so it's ranked last. A dash in the self-transfer column means no self-transfer was cheaper than that tool's protected fare. Prices are live and drift by the hour, so read the pattern, not the exact euro.
The cheapest fare is often a stripped "Light" or "Basic" ticket with only a cabin bag and no checked luggage. It's easy to assume this only applies to low-cost airlines, but it doesn't. The cheap Aer Lingus and self-transfer fares on this route often come without a checked bag, and to the US that's a real gap.
Adding a checked bag costs roughly €30 to €70 each way, sometimes more. On a €495 fare, a €120 round-trip bag fee eats over half the gap to the nonstop. Add your bag before you compare prices, and check what the cheap fare actually includes.
This is exactly why the nonstop deserves a look: the KLM/Delta nonstop we saw at €650 already included a checked bag. Once you add luggage to a cheap 1-stop, the gap to a faster, simpler nonstop closes fast.