Jakob Nielsen, one of the leading experts on usability, suggests that 10% of a website development budget should be spent on usability and that this investment doubles the usability of the redesigned site. On average, Nielsen says that this usability improvement leads to the following improvement in site statistics:

• 100% improvement in sales
• 150% improvement in traffic and visitor counts
• 161% improvement in user performance and productivity
• 202% improvement in use of specific site features

• For every dollar spent acquiring a customer you will spend $100 dollars reacquiring them after they leave because of poor usability or bad customer service
• More than 95% of your customers will use less than 5% of the features and functions of your site. Customers will NEVER use about 75% of the functions on your site.
• The single largest predictor of call center volume is your web site’s usability
• For every $10 spent defining and solving critical usability problems early in development using professional usability research, you will save about $100 in development costs.
• For every dollar you spend improving the visual design or style of your site, you will receive virtually no improvement in sales. The same dollar spent on improving core behavioral interactions with your site’s critical way-finding and form-filling functions will, however, return $50-100 if executed in a professional and rigorous manner.