"Three hours before the flight" is the advice everyone repeats, and it's the source of the single most expensive mistake in airport travel: treating it as the time to leave home rather than the time to be in the terminal.
Here is what the airports themselves say, what the deadlines inside the building actually are, and how to turn all of that into a pickup time.
What Heathrow and Gatwick recommend
Heathrow recommends arriving 2 hours before a short-haul flight and 3 hours before a long-haul flight. It also publishes three deadlines that matter more than the arrival target, because missing any one of them ends your trip:
- Check in at least 90 minutes before departure
- Enter security at least 60 minutes before departure
- Gates are announced around 45 minutes before departure
Gatwick recommends arriving at least 2 hours before your flight to check in and clear security. Its check-in desks typically open 4 hours before long-haul and European departures, and 2 hours before UK and Ireland flights.
(Both sets of figures are from the airports' own pages — Heathrow and Gatwick — as of 18 September 2026. Your airline can set tighter deadlines than the airport, so its rules win where they differ.)
The number that actually matters
Work from the bag drop deadline, not the arrival target. If check-in closes an hour before departure and you arrive 65 minutes before, you have technically "made it" and will still probably miss the flight, because the queue doesn't care.
So the order of events is:
- Departure time
- Minus the airline's check-in/bag-drop cut-off
- Minus queueing time at bag drop and security
- Minus the walk to the gate, which at a large terminal is longer than it looks
That's why the airports' 2- and 3-hour numbers exist. They're not padding — they're the queue.
Add time for the things that reliably go wrong
Beyond the baseline, add margin when any of these apply:
- School holidays, half terms and bank holidays, when families with hold luggage fill the bag-drop queues.
- Peak departure banks — early morning at Heathrow and Gatwick is the busiest stretch of the day.
- You're checking bags rather than travelling hand-luggage only.
- You need assistance, are travelling with small children, or have sports equipment to check in.
- Non-UK or non-EU passports, where document checks at the desk take longer.
Now work backwards to your pickup time
This is the part most people get wrong. Your pickup time is:
Target arrival time at the terminal − journey time − a traffic buffer
The journey time is the variable you can't control, so check a live route planner for your actual departure time rather than assuming the off-peak figure. A run that takes 40 minutes at 4am is a different journey at 8am.
A worked example for a 10:00 long-haul flight from Heathrow:
- Be in the terminal by 07:00 (3 hours before)
- Journey of, say, 45 minutes at that hour → leave at 06:15
- Traffic buffer of 20–30 minutes → pickup at 05:45–05:55
Note how a "10am flight" becomes a before-6am pickup. That's normal, and it's why early-morning bookings should be made well in advance — our early morning airport guide covers pre-dawn departures in detail.
Coming back the other way
Arrival is a different calculation entirely. The gap between landing and walking into the arrivals hall is anything from twenty minutes to well over an hour, depending on immigration and baggage reclaim — which is why an airport pickup should be booked against your flight number, not your landing time. Our waiting time guide explains how that works.
Can you arrive too early?
Mildly, yes. Check-in desks open on a schedule — 4 hours before long-haul at Gatwick, for instance — so turning up 5 hours early means waiting landside with your bags. Gatwick's twilight bag drop, where some airlines take your hold luggage the evening before an early flight, exists precisely for this problem; check whether your airline offers it before planning around it.
For most people the risk runs the other way. An hour spent in the departure lounge costs you an hour. An hour short at bag drop costs you the flight.
Frequently asked questions
Q: How early should I get to Heathrow? A: Heathrow recommends 2 hours before a short-haul flight and 3 hours before a long-haul flight, and separately advises checking in at least 90 minutes and entering security at least 60 minutes before departure.
Q: How early should I get to Gatwick? A: Gatwick recommends arriving at least 2 hours before your flight. Check-in typically opens 4 hours before long-haul and European flights, and 2 hours before UK and Ireland flights.
Q: Is 2 hours enough for an international flight? A: For a short-haul European flight it usually is, but for long-haul both airports advise longer, and your airline's own check-in deadline takes priority over the airport's guidance.
Q: What time should my airport transfer pick me up? A: Work backwards: target terminal arrival time, minus journey time, minus a traffic buffer. A 10am long-haul departure often means a pickup before 6am.
Q: What happens if I miss the bag drop deadline? A: You will usually not be able to check a bag on that flight, even if the plane hasn't left. That deadline, not the departure time, is the one to plan around.
Working out a pickup time? Get an estimate for your transfer — or see fixed airport transfer prices for your area.