The ideal cover letter should be four paragraphs. Each paragraph needs to focus on a specific theme, usually answering some of the key requirements of the job specification and how your skills and experience match these requirements.
Be sure to keep your sentences short and to the point. It is also good practice to use the STAR method when giving examples of how you exceeded existing/previous employers expectations, which will be closely correlated with the specifications of the role you are applying for.
The four paragraphs should fit neatly into one page, as a recent study of hiring managers found that 70% stated they would prefer if cover letters they received are less than one page.
Remember, that white space is good and first impressions matter. Therefore, avoid trying to squeeze everything into one page as a first impression which conveys clutter and chaos is not something you want to pursue.
In conclusion, the ideal cover letter should be no more than four paragraphs, with plenty of white space and will fit neatly into one page. The content should highlight your most relevant skills and experience which meet the specifications of the job. It is important to remember that recruiters spend an average of six seconds reading a cover letter, so if you can get them to remember three key points in six seconds which arouses their curiosity, you are doing exceptionally well.