Is there an percentage of duplicate content required before you should use a canonical tag?

[punchseo]

Is there a percentage (approximate or exact) of duplicate content you should have before you use a canonical tag? Similarly how does Google handle canonical tags if the pages aren’t 100% duplicate?

I've added some background and an example below;

• Nike Trainer model 1 – has an overview page that also links to a sub-page about cushioning, one about Gore-Tex and one about breathability.
• Nike Trainer model 2,3,4,5 – have an overview page that also links to sub-pages page about cushioning , Gore-Tex and breathability.

In each of the sub-pages the URL is a child of the parent so a distinct page from each other e.g.

• /nike-trainer/model-1/gore-tex
• /nike-trainer/model-2/gore-tex.

There is some differences in material composition, some different images and of course the product name is referred multiple times. This makes the page in the region of 80% unique.

[badgergravling]

There's no exact rule as far as I'm aware, but generally 75-80% unique is a commonly quoted threshold.

The actually amount of duplicate content on a page won't affect how Google handle a canonical tag - either the tag is there or not, just the same as a redirect etc.

[punchseo]

Hi Dan

Thanks for coming back.

Great, so canonicals will be taken into consideration regardless.

Do you have any suggestions on how to mitigate the negative effects of duplicate content if it is unavoidable? Hypothetically. Excluding canonical tags?

Thanks again.