Cognitive Load Calculator

Cognitive load is the mental effort a task demands. Psychology has measured it since Sweller’s work in 1988, but almost nobody puts a number on their own, which is what this page does: it turns five things you can count right now into a single percentage of your working capacity.

The four things that eat capacity

The score adds up four sources, each capped so no single one can swamp the others:

Complexity is 1 for routine work, 2 when it needs focus, 3 for heavy thinking. So three complex projects score 3 × 3 × 8 = 72, which the cap trims to 50. The total is capped at 100.

Reading the result

• Under 30%: light load, room to take on more and still learn
• 30 to 50%: a good working level, which is where most productive days sit
• 50 to 70%: heavy, and adding anything else will cost you somewhere
• 70 to 90%: overloaded, time to defer or hand off
• Over 90%: you will make mistakes, so stop and prioritise before you do

Worked example

Five active projects at moderate complexity, eight decisions waiting, four interruptions an hour, and five hours of sleep:

• Tasks: 5 × 2 × 8 = 80, capped at 50
• Decisions: 8 × 3 = 24
• Interruptions: 4 × 4 = 16
• Sleep: (7 − 5) × 5 = 10
• Total: 50 + 24 + 16 + 10 = 100%, critical overload

That is the point of the caps. Five moderate projects alone already max out the task component, so the decisions and interruptions are pure overflow. Put those numbers in and the calculator returns exactly 100%.

Why sleep is scored separately

The other three are demands you could in principle put down. Sleep debt is different: it shrinks the capacity available to meet them, which is why it counts against you in the total and reduces the green wedge in the chart at the same time. Two hours short is not two hours of lost work, it is a 10% narrower channel for everything else you do that day.

The three kinds of load, and which one you can actually cut

Sweller separated intrinsic load, which is complexity built into the task and cannot be removed, from extraneous load, which comes from bad tools, unclear instructions and interruption, and germane load, the productive effort of actually learning something. Only the middle one is waste. The interruption count above is the closest thing this calculator has to a direct measure of it, and it is usually the cheapest number to improve: closing a chat client is easier than making the work simpler.

Working memory holds roughly four chunks at once. Miller’s famous “seven plus or minus two” is the older estimate and later work revised it down. This matters because chunking is what expertise buys you. A chess master looks at a board and sees three or four familiar shapes where a beginner sees thirty-two separate pieces, and the position costs the master almost nothing to hold.