What is the forgetting curve?

The forgetting curve describes how people lose newly learned information over time when they do not review or use it. Memory drops fastest soon after learning and then levels off. The German psychologist Hermann Ebbinghaus first measured it in experiments he published in 1885.

Reviewed by Clark Quinn, Chief Learning Strategist Updated October 28, 2026

Example

A manufacturing company runs a half-day safety induction for new line workers. Four weeks later, a supervisor notices that several of them cannot list the lockout steps for the machine they operate, even though they all passed the end-of-course quiz.

The L&D team recognizes the forgetting curve. The workers knew the steps on day one and then had few chances to recall them. The team keeps the induction but adds short reviews after it: a two-question quiz on day 3, a one-minute video on the lockout sequence on day 10, and a supervisor walkthrough at the machine on day 21. A card listing the steps also goes up beside each machine. For the next group of new hires, the four-week check becomes part of the plan instead of a surprise.

How it works

What Ebbinghaus measured

Hermann Ebbinghaus wanted to measure memory without the influence of meaning or prior knowledge. He memorized lists of nonsense syllables (made-up combinations such as “ZOF”) until he could recite them without error. He then relearned each list after an interval, from minutes to about a month, and measured how much time he saved compared with learning it the first time. A smaller saving meant more forgetting. He was his own and only test subject, and this approach is known as the savings method.

Plotted against time, his results drop steeply in the first hours and day, then flatten out. That shape is the forgetting curve.

The shape of the curve

The curve has two parts:

• A steep early drop. Most of the loss happens soon after learning, within the first day or two.
• A long, slow tail. After that, forgetting continues at a much slower rate, and part of what was learned stays for a long time.

Reviews reset the curve

Each time a learner recalls the material, forgetting starts again from a higher point and proceeds more slowly. Plotted together, several well-timed reviews produce a series of curves, each flatter than the one before. This is the idea behind spaced repetition.

What affects how fast people forget

Ebbinghaus chose meaningless material on purpose, so his curve is close to a worst case. In workplace training, several factors change the rate:

• Meaning. Content that makes sense and connects to what people already know is easier to keep.
• Repetition and recall. Material that has been recalled several times fades more slowly than material seen once.
• Use on the job. Skills people apply soon and often stay. Procedures used once a year fade.
• Emotion and relevance. Information tied to a real consequence or a vivid example tends to be remembered better.
• Overload. Long sessions that cover too much leave less of each point behind.

How to slow the forgetting curve

• Spread the learning out. Spreading the same study time across several sessions works better than one long session.
• Ask for recall, not rereading. Questions, knowledge checks and scenarios strengthen memory more than repeating the slides.
• Get people using the skill quickly. Practice on the job soon after training, with a supervisor or a job aid for support, keeps the skill in use.
• Keep reviews small. Breaking content into microlearning units makes reviews quick to send and quick to complete.
• Be careful with precise figures. Percentages often quoted for how much people forget in a day or a week vary widely with the material and the learner. Treat them as illustrations, not benchmarks.

Why it matters for L&D teams

• Completion is not retention. A passed end-of-course quiz shows what people knew that day, not what they will remember when they need it.
• It explains the post-training dip. When performance slips weeks after a course, forgetting is often the cause, even if the course itself was sound.
• It justifies reinforcement. The curve gives L&D teams a clear reason to budget for follow-up reviews as well as new courses.
• It shapes safety and compliance plans. Procedures people use rarely are the ones most likely to be forgotten, so they need planned refreshers.