Mark Zuckerberg’s 80% rule: How leaving space on your calendar can boost productivity and prevent burnout

Mark Zuckerberg

Many people equate a full calendar with importance, believing that constant busyness signals success. Yet real achievement often comes not from cramming every hour, but by deliberately leaving space. Meta CEO Mark Zuckerberg recently shared that he keeps part of his calendar intentionally open, a practice that helps him focus on meaningful work and avoid burnout.

What is the 80% rule?

Zuckerberg explained in a conversation with John Collison of Stripe that he avoids back-to-back meetings, particularly one-on-ones, as excessive scheduling can be frustrating and detract from higher-value projects. Without room for flexibility, emergencies or creative work get sidelined. Productivity research supports this approach, showing that fully packed schedules lead to fatigue, mental resistance, and diminished output.

The principle, often called the “80% rule,” encourages leaving around 20% of your work hours unscheduled. Google applies this formally, advising employees to book only 80% of their time so they can respond to urgent matters or pursue side projects. Laura Mae Martin, a Google productivity expert, emphasises that this buffer allows workers to adapt rather than be derailed by unexpected tasks.

Thinkers such as Tom DeMarco, in his book Slack, and Oliver Burkeman, author of Four Thousand Weeks, echo this approach. They caution against overfilling schedules, arguing that innovation needs space. Iconic figures such as Steve Jobs and Albert Einstein deliberately set aside time for thinking, problem-solving, or curiosity, which fuelled some of their greatest breakthroughs. Leaving the final fifth of your day free allows for deeper focus, adaptability, and greater enjoyment at work.

If high-profile leaders protect parts of their calendars from constant meetings, it may be time for everyone to do the same. Embrace blank spaces, plan just 80% of your day, and use the freedom to tackle complex problems, explore ideas, or simply respond to the unexpected.