Need Advice on the 90/180 Rule

[akmoolah]

Hello guys, i Need your advice.

I have a schengen Tourist visa which is a multiple visa for 1 year(s). Maximum allowed days to stay is 90 . It expires on 14/02/2018.

I have travelled already to schegen state for 19 days starting in April this year from 20/04/2017 to 09/05/2017.

I want to go to Europe again for 2 months or more in August.

Now if i go to Europe from 15/08/2017 until 23/10/2017 . Will this cause a problem because i wont be exceeding the 90 days rule but my 180 day period will be expired on 18/10/2017 .

How will they look about this?

Please need your suggestion because i am confused as i know that they count the 180 from the first time you land.

Judging by this will this be considered overstaying?

[steven]

Between dates 20/04/17 and 09/05/17 you stayed 20 days.
Between dates 15/08/17 and 23/10/17 you will have stayed additional 70 days.
As of 23/10/17, that amounts to 90 days.
Staying 90 days in the Schengen zone satisfies the 90/180 rule.

The 180 days period does not expire. It is a moving period, it moves one day forward each day that you stay in the Schengen area.