Meta Description length?

Noticed FSB advises if the meta description is over 180 Characters.

What is the thinking behind this as currently any articles I have read on SEO suggest that Google cuts off at 154 characters?

If that figure is true I suggest a change to the parameter in future versions of FSB or even better, a dynamic checking display like in Yoast SEO plugin i.e when the maximum length is exceeded the text changes colour. This would make it much quicker and more accurate when editing or creating…

Meta Description length?