London Heathrow to Seattle Tacoma liquid rules
LHR → SEA · United Kingdom → United States
Outbound flex, return tight. You can take larger liquids out, but not necessarily back. Pack to 100ml unless you're checking luggage on the return journey.
Rule basis: Both airports have official guidance we can show (see each airport's source and check status).
What to do: Conservative packing fallback: containers of 100ml (3.4oz) or less in one clear quart-sized resealable bag, ready to take out at security. US airports (TSA 3-1-1) require a clear quart-sized resealable bag; the other airport's own bag rule is shown on its card. Exceptions: LHR: Flights to Australia: liquids in containers over 100ml can't be taken. LHR: Metal and insulated containers (e.g. flasks) must be empty. SEA: TSA lists medications and infant/child nourishment as exemptions to the 3.4oz (100ml) limit — tell the officer; they may need extra screening. SEA: Duty-free liquids over 3.4oz (100ml) are allowed only on international journeys connecting in the US, in the retailer's sealed tamper-evident bag with the receipt (bought within 48 hours), and must still pass screening.
Liquid Limits is a travel planning tool, not an official aviation source. Always confirm with the airport before you travel.
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Outbound · LHR
- Flights to Australia: liquids in containers over 100ml can't be taken.
- Metal and insulated containers (e.g. flasks) must be empty.
Return · SEA
- TSA lists medications and infant/child nourishment as exemptions to the 3.4oz (100ml) limit — tell the officer; they may need extra screening.
- Duty-free liquids over 3.4oz (100ml) are allowed only on international journeys connecting in the US, in the retailer's sealed tamper-evident bag with the receipt (bought within 48 hours), and must still pass screening.
What to pack in cabin baggage
Conservative packing fallback: containers of 100ml (3.4oz) or less in one clear quart-sized resealable bag, ready to take out at security. US airports (TSA 3-1-1) require a clear quart-sized resealable bag; the other airport's own bag rule is shown on its card. This works at both LHR and SEA, including any exceptions listed above. Keep medications and contact lens solution accessible — they can usually go above the limit.
What to check in hold luggage
Full-size shampoo, perfume, sunscreen, olive oil, jam — anything over the limit. Wrap glass in clothes and seal liquids in plastic bags in case pressure changes pop the lids.
Common items people lose on this route
Packing checklist for LHR → SEA
A short checklist for this trip — pack what you need to stay within the rules above.
Match the stricter airport's 100ml limit.
Required for liquids at the security tray.
Anything bigger goes in the hold.
Return-flight reminders — coming later
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