"When should I leave?" has three parts: how long before the flight you need to be at the airport, how long the journey takes, and how much margin to add for the things that go wrong. Get those three right and the morning of a flight stops being stressful. Let's build the number.
01 / AT THE AIRPORTHow early to be at Heathrow
Airlines publish their own guidance, and it's the figure to follow — but as a general rule of thumb:
Remember the cut-offs: bag drop and gate closing happen well before departure (often 30 to 60 minutes prior), so "arriving before the flight" isn't enough — you need to be there before those deadlines.
02 / THE JOURNEYAdd your real travel time
Next, add how long it actually takes to get to Heathrow at your travel time. From central London by car that's roughly 45 to 75 minutes off-peak, longer in rush hour — and more from further out. Be honest about the time of day: a 6am departure means a pre-dawn drive (quick roads, but no trains), while a 9am flight means leaving straight into the morning peak.
03 / THE BUFFERMargin for the things that slip
Finally, add a buffer for the unpredictable: traffic incidents, a slow bag drop, long security queues, or simply a busy day. A modest margin here is the difference between a relaxed coffee airside and a panic at the gate. The busier the period — school holidays, bank holidays, peak mornings — the bigger the buffer should be.
The formula: leave-home time = flight time − airline's recommended arrival window − realistic drive time − buffer. For a long-haul morning flight from central London, that can easily mean leaving three to four hours before departure. Write it down the night before so it's not a half-asleep guess.
04 / WORKED EXAMPLEPutting it together
Say you have a long-haul flight at 10:00am from central London:
- Be at Heathrow ~3 hours before → 07:00.
- Morning-peak drive of up to ~75 minutes → leave by ~05:45.
- Add a buffer for peak traffic and a busy terminal → aim to leave ~05:30.
For a short-haul 7:00pm flight, you'd be at the airport ~2 hours before (5:00pm), but the evening peak means leaving central London by mid-afternoon to be safe. The exact numbers shift with your start point and airline — the method is what matters.
05 / MAKE IT EASIERHow a pre-booked transfer takes the guesswork out
Booking a transfer lets you fix the pickup time around this calculation, with a driver who knows the quick routes to your terminal and a fixed fare that doesn't surge at 5:30am. For the return, flight tracking means your pickup adjusts to the real landing time. It won't shrink the buffer you should leave — but it removes the "will a car even come at this hour?" worry from the equation.
06 / FAQFrequently asked questions
How many hours before a flight should I arrive at Heathrow?
As a general guide, around 2 hours for short-haul and 3 hours for long-haul, but always follow your airline's advice, which can be longer at busy times. Then add travel time to work out when to leave.
When should I leave home for a Heathrow flight?
Work backwards: airline's recommended arrival time, plus a realistic drive time for the hour, plus a buffer. For a long-haul morning flight, that can mean leaving several hours ahead.
What time do check-in and bag drop close?
They vary by airline and flight, typically opening a few hours before and closing 30 to 60 minutes before departure. Check your airline's exact times — missing the bag-drop cut-off can mean missing the flight.
Should I leave extra time at busy periods?
Yes. Holidays, peak mornings and major events add time on the roads and at the terminal. Build a larger buffer, and consider a pre-booked transfer so your pickup is timed and the fare fixed.
Is it better to be early at the airport?
Generally yes — being early is low-cost (a coffee airside) while being late can cost you the flight. Aim for comfortably early rather than cutting it fine.
Can a transfer guarantee I make my flight?
No transfer can promise against traffic incidents, but timing the pickup to your flight, using local routing and leaving a sensible buffer stacks the odds firmly in your favour.
Time Matters
Leave on time, arrive calm
Pre-booked Heathrow transfers timed to your flight — local routes to your terminal, a fixed fare with no surge, even at 5am. Confirmed before you ride.