In the graph below you see the time zone difference between Greenwich Mean Time and Pacific Daylight Time. Drag the bubble to adjust the time and to see the corresponding time in the other time zone.
Greenwich Mean Time is the time zone of the 0 meridian, located in London, United Kingdom, including cities like London, Lisbon and Dublin (in the winter). Pacific Daylight Time is the time zone of the Canadian and US West Coast when observing daylight saving time in the summer, with places like Seattle, Vancouver, San Francisco and Los Angeles.
Usually it is preferable to schedule meetings in the late afternoon for the person in GMT and before lunch for the person in PDT.
GMT, or Greenwich Mean Time, is the zero when it comes to time zones – they are all counted from the zero meridian that runs through the village of Greenwich.
While both the UK and Portugal are officially on GMT you need to pay attention to whether they are actually observing it or are using their own. Britain in the summer for example use British Summer Time – which is different than GMT.
London, Lisbon, Dublin, Edinburgh
GMT does not observe DST as it is the zero hour time zone – it never changes.
Pacific Daylight Time is the time of the Western United States and Canada and is typically abbreviated as PDT. It is 8 hours behind GMT. Although PDT is for the Western part of the US and Canada it is not the Westernmost – both Hawaii and Alaska are on their own time zones due to their location.
Pacific Daylight Time is for the Western US and Canada and thus include locations such as Vancouver, Seattle, San Francisco and Los Angeles. It also extends halfway down Baja California in Mexico. In addition to California and Washington also Nevada and Idaho are on PDT in the summer.
PDT is only used in the summer months so you will need to pay attention to when the switch takes place. Daylight Time is in the Pacific area observed from November to March and is one hour ahead of Pacific Standard Time.