London has five airports, and the received wisdom is simple: Stansted and Luton are the "cheap" ones, Heathrow is where you overpay. Like most received wisdom, it's half right — and the half that's wrong can cost you.
The sticker price isn't the whole price
Stansted and Luton host the low-cost carriers, so their headline fares often _are_ the lowest. But two things muddy that:
- Getting there. Stansted and Luton are well outside central London. Once you add the train or
coach — and the time — a "cheaper" fare can quietly lose its edge, especially at antisocial hours when a red-eye departure means a pricey late-night transfer.
- Route coverage. For long-haul, Heathrow is often the _only_ realistic option, and Gatwick
covers a lot of leisure long-haul the budget airports simply don't fly. On those routes the cheap-airport question doesn't even arise.
So "which airport is cheapest" only has a real answer _per route_ — and that's a data question, not an opinion.
What our data actually shows
Flight Signal tracks all five London airports — Heathrow (LHR), Gatwick (LGW), City (LCY), Luton (LTN) and Stansted (STN) — and records the cheapest fare we observe from each. On every destination price-history page there's a "cheapest by London airport" table showing exactly which airport won for that route, from real observations rather than reputation.
Some patterns hold up: short-haul European city breaks frequently come out cheapest from Stansted or Luton. Others surprise people: plenty of routes are cheapest from Gatwick or even Heathrow once you account for who flies them. The only way to know for your trip is to look at the route.
How to use it
1. Open the price-history page for where you want to go. 2. Check the "cheapest by London airport" table — that's observed, not assumed. 3. Mentally add your transfer cost and time to the budget-airport fares before deciding.
We weight your preferred airports first when scoring deals (by default Heathrow, then Gatwick), and Luton only alerts when a fare is genuinely exceptional — so you're not pinged about a Luton red-eye unless it's a steal. You can read the reasoning in our methodology.
The honest bottom line
There's no single cheapest London airport — there's a cheapest airport _for your route, on your dates_. The budget airports win often enough to be worth checking, but not so reliably that you should book blind. Look at the history, add the transfer, then decide. Or let us watch every airport for you and tell you when a genuine deal appears from any of them.