Any software that can help with this ?

i think, you can search here

http://www.warriorforum.com/search.p...rchid=27698587

Keyword density Nothing between How many times our keywords optimizing in website or web pages. You can 2 to 3 keywords are Enough for Ranking, over optimization always affecting your website ranking on search Engines

Your doing it wrong...

I am writing a post about Yukon. I need to make sure that I use the word "Yukon" so many times, to achieve exactly a 5.50% keyword density - which is the safe amount to avoid getting hit by an algorithmic penalty.

By creating a post of 1,000 words, and using the word "Yukon" 55-times, I will achieve 5.50% keyword density - which will surely push me to #1 for the keyword "Yukon". I will also add 20 images with the alt tag "Yukon", and roughly 5-10 headings with "Yukon" in them.

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Jesus. OP, you're doing it ALL wrong. Stop writing for the god'damn search engines and write for your audience.

Google doesn't look at keyword density anymore - they haven't for years. It's so easy so manipulate. Google look at the whole post and try to identify what topic is belongs to. That's why huge 6,000 word posts covering a whole topic rank well above a 500 word "targeted" post. Search is moving more towards "topics" and not "keywords".

The only way you can cover a whole topic is to write naturally with expert knowledge. If you're writing about politics, and you don't know who the UK prime minister is, then stop and move on. Find a subject you are knowledgeable in and work on it.

Overoptimizing is indeed a very bad thing.

But I think you should focus only on the quality you provide in your articles and don`t think to much about keywords density. Long time ago 10% was safe, these days it`s a lot lower, you have no guarantee tomorrow even 1% will be ok for Google, they are changing their mind all the time.

What will you doo after some period of time when you have a lot of articles and that threshold will get lower ?
Rerwite all the articles ?

It`s waste of time in my opinion, it`s a lot better to focus on quality and don`t think about keywords density too much. Low bounce rate will be a signal to Google your website is HQ and your ranks will get higher. Build quality backlinks vary anchors. Focusing these days on specific keyprhases is the route to nowhere , Long Tail is the way to go. Try to use the tool like SEMRUSH ,spy your competitors which keywords they are targetting for and use them in your backlinks strategy.