Appropriate length for Meta keywords & description ?

SEO experts have researched and commonly agreed that meta descriptions can be any length, however search engines (especially Google) generally truncate snippets longer than 160 characters. It is thus highly advisable to keep meta descriptions long enough that they're sufficiently descriptive, but shorter than that 160-character limit.

Regarding meta keywords, please watch a youtube video by Matt Cutts on the topic: Google does not use the keywords meta tag in web ranking. Google and Bing ignored meta keywords for years and places no weight in them to rank pages. Yahoo may read them but this should not be your worry. Having said this, and as per the SEO expert advice, you may just want to create a few meta keywords for other "not-popular" search engines.

 

The good Meta descriptions can be longer between 160 to 200 characters, it is top to keep Meta Description long sufficient that they're suitably descriptive, but shorter than that 160-character limit.

Meta keywords have no effect on SEO now a days, but the good Meta Keywords between 100 to 255 characters, just be assured to place in the words that match your page's content

 

Description length you can go for 160 char, ideally we never go for meta keyword it's treated as keyword stuffing. No official length of keywords in meta, you can mention 100 char max......

 

I don't exceed above 63 words. Otherwise the Google will not show anything it will crop after 63 characters.

 

It is now about 300 words for the page meta description, according to Google. This changed about 1 month ago.