About Day CPU

Day CPU is a collection of free and easy-to-use day calculation tools. We help people add and subtract days, calculate days between dates, find weekdays, and discover birthdays.

Our mission

Our mission is to make calendar math simple for everyone. Whether you’re planning a project deadline, checking when your next birthday falls, or just curious about “what day is 100 days from now”, Day CPU gives you the answer instantly.

Who we are

Day CPU is an independent project focused on clarity, accuracy, and speed. All calculations run directly in your browser using modern calendar algorithms (Gregorian calendar rules).