St Pancras to Heathrow Terminal 5 transportation help

Wouldn't it be taking the best route in the opposite direction?

https://search.ricksteves.com/?button=&date_range=6m&filter=Travel+Forum&query=st+pancras+heathrow&utf8=%E2%9C%93

Will this be cutting it too close?

Your trip requires perfect execution to be successful.

( cue the Clint Eastwood/Dirty Harry clip... "Do you feel lucky?.... well do you?" )

Not saying it cannot be done, but it would be more drama than I would want. Check the cost of the walk cost of a ticket from LHR to your destination and decide if that is a bet you would place on a single hand of blackjack.

Use the TFL website. It doesn't get much simpler: walk to Kings Cross underground. Take the Picadilly line to Heathrow Terminal 5. It will take about an hour. And yes, that's cutting things close. Sure hope your Eurostar isn't late arriving. Not a gamble I'd be willing to take

Can you fly to your destination from Amsterdam?

The most straightforward way from St Pancras to Heathrow is to walk swiftly from the Eurostar terminal to the tube station below St Pancras, then hop on a Piccadilly line tube which will take you all the way to Heathrow in about an hour.

If you got your timings right I guess you might save some time by switching to the Heathrow Express at Paddington but I think it would be a minimal saving.

Generally speaking, if all goes well you can get from St Pancras to Heathrow in an hour by tube. But bear in mind you’re relying on your train from Amsterdam being on time, then it can take a long time to get off the train and move through St Pancras.

I’ve used - or tried to use - Eurostar on three occasions. The first time, all trains were cancelled due to a body on the line. The second time, all trains between Brussels and Amsterdam were cancelled due to storms and high winds. The third time, everything went absolutely like clockwork. So: as the previous poster said, do you feel lucky?

In case there is flexibility in your plans, it may not be ideal to take a four-hour train journey, for which you’ll need to check in 60 minutes in advance, get to London, have a nail biting hour-long transfer then check in for a flight - when there’s an international airport right there in Amsterdam. I’d only take the train from Amsterdam to London to actually go to London.

That is high stakes living.

What if the Eurostar is delayed for any reason at all? It happens. What if any of the 3 routes below is having problems on the day? It happens.

Whoever said 2 1/2 hours is plenty is not going to be there to pick up the pieces and buy you a new air fare home when it all goes pear shaped. Yes everything may run to time, yes you may find 2 1/2 hours is adequate. But there are very good reasons why everyone advises 3 hours- including all public transport operators, airlines and the airport.

I can't think why you are not flying from Amsterdam.

So in a very optimal world you will arrive at between 1152 and 12 noon.

These are TfL timings and assumes a HEX is just about to leave from Paddington (runs every 15 minutes)-51 to 52 minutes-
ROUTE 1-
Walk to King's Cross St. Pancras Underground Station
Walk to King's Cross St. Pancras Underground StationJourney time:6 min
Step 2
DepartKing's Cross St. Pancras Underground Station at 19:06viaCircle line to Paddington (H&C Line)
Circle line to Paddington (H&C Line)Journey time:10 min
Step 3
DepartPaddington (H&C Line)-Underground at 19:17viaWalk to Paddington Rail Station
Walk to Paddington Rail StationJourney time:8 min
Step 4
DepartLondon Paddington Rail Station at 19:25viaHeathrow Express to Heathrow Terminal 5
Heathrow Express to Heathrow Terminal 5Journey time:21 min
Step 5
DepartHeathrow Terminal 5 Rail Station at 19:46viaWalk to Heathrow Terminal 5
Walk to Heathrow Terminal 5Journey time:5 min
Arrive atHeathrow Terminal 5 at 19:51Heathrow Terminal 5

ROUTE 2- ELIZABETH LINE (far more frequent trains)- 1 hour 1 minute-
Walk to King's Cross St. Pancras Underground Station
Walk to King's Cross St. Pancras Underground StationJourney time:8 min V
Step 2
DepartKing's Cross St. Pancras Underground Station at 20:17viaMetropolitan line to Farringdon
Metropolitan line to FarringdonJourney time:2 min
Step 3
DepartFarringdon at 20:27viaElizabeth line to Heathrow Terminal 5
Elizabeth line to Heathrow Terminal 5Journey time:38 min
Step 4
DepartHeathrow Terminal 5 Rail Station at 21:05viaWalk to Heathrow Terminal 5
Walk to Heathrow Terminal 5Journey time:5 min
Arrive atHeathrow Terminal 5 at 21:10Heathrow Terminal 5

ROUTE 3- UNDERGROUND 1 hour 12 minutes-
Walk to King's Cross St. Pancras Underground Station
Walk to King's Cross St. Pancras Underground StationJourney time:8 min
Step 2
DepartKing's Cross St. Pancras Underground Station at 19:39viaPiccadilly line to Heathrow Terminal 5
Piccadilly line to Heathrow Terminal 5Journey time:1 h 0 min
Step 3
DepartHeathrow Terminal 5 Underground Station at 20:39viaWalk to Heathrow Terminal 5
Walk to Heathrow Terminal 5Journey time:4 min
Arrive atHeathrow Terminal 5 at 20:43Heathrow Terminal 5

Go to the tfl.gov.uk website which allows you to plan journeys by train, tube and bus. They came up with take tube from St Pancras to Paddington, take Heathrow Express from Paddington to LHR, total time for journey is shown as 53 minutes including the in between walking from tube to station.

It is way too tight between train arriving and flight departure as it does not allow for any hold-ups. I have always allowed the full three hours before departure from LHR. Have sometimes whipped through security in 20 mins or so, but more likely it has taken at least a couple of hours for check in and security, even with carry on and on-line check in.

Hi, as your name is Beatnikbean, I'm hoping you are a traveler used to walking a lot, hopefully fast!
Earlier this summer I arrived at Heathrow 3 hours early, checked in easily then sat around a long time. Are you checking in luggage, or taking in onboard? Spend your time on the train getting your bags ready, i.e., get all your liquids together ready to put in a baggie. Double check that you don't have anything that can't be taken onboard. That way you're ready to go once you arrive at the airport. I don’t know current flight statistics, but at least the student holidays are over and it’s not Christmas travel time, so that helps. Do use the Elizabeth line, its quick, airconditioned and comfortable, the Piccadilly is very slow and it will drive you nuts. Don't worry if you don't have an Oyster card, you can now just use your credit card to tap in and out of the stations.
Have you been to St. Pancras before? If not, look at the sitemap. I see you have been given information on the tube to the Eliz line. If you need to look at the Underground map, this is the link:
https://tfl.gov.uk/maps/track/tube

I hope it works out.