What Is the Forgetting Curve? – How to Make Training Stick

A team finishes a well-designed training program, and assessment scores are strong. Six weeks later, managers report that people are making the same mistakes they made before. What happened? Usually nothing went wrong in the course; memory simply did what memory does when nothing reinforces it. What is the forgetting curve, and what can you do to make training stick?

The forgetting curve describes how memory for newly learned information declines over time, quickly at first and then more slowly, unless it is reviewed or used. It comes from experiments that German psychologist Hermann Ebbinghaus ran on himself in the 1880s, memorizing lists of nonsense syllables and measuring how much time he saved when relearning them later. The steepest drop happens in the first hours and days. The good news is that the curve is not fixed. Spaced review, retrieval practice, meaningful content and real use on the job all slow forgetting considerably.

What Did Ebbinghaus Actually Measure?

Ebbinghaus wanted to study memory in a controlled way, so he removed meaning from the material. He memorized lists of nonsense syllables, such as consonant-vowel-consonant combinations, until he could recite them perfectly. After a delay, he relearned the same lists and recorded how much less time the second learning took. That reduction, called savings, was his measure of what memory retained.

He published the results in 1885 in a book usually translated as Memory: A Contribution to Experimental Psychology. The chart below shows his savings scores at seven delays, as commonly reported from his data.

Notice the shape: savings fell sharply within the first day, then leveled off. Even a month later, relearning was still faster than learning from scratch, which means some memory remained. A 2015 replication by Jaap Murre and Joeri Dros followed the same method and produced a very similar curve. The forgetting curve overview covers the original work and later research in more detail.

Do Employees Really Forget 70% of Training in a Day?

Probably not, at least not as a general rule. You may have seen claims that people forget a fixed percentage of training within 24 hours or a week. Those numbers are usually presented without a source, and they don't come from Ebbinghaus in that form.

There are three problems with applying his curve directly to workplace training. First, his material was deliberately meaningless, whereas meaningful content connected to what people already know is generally retained far better. Second, he measured savings in relearning time, not the percentage of information someone can recall. Third, the rate of forgetting depends heavily on how well something was learned to begin with and whether it gets used.

The shape of the curve is real and well replicated: fast early decline, then slower loss. The specific percentages don't transfer to your compliance course. When I see a vendor pitch built on a precise forgetting statistic, I ask for the source, and I'd encourage you to do the same.

Why Do People Forget What They Learned?

Researchers generally point to a few overlapping causes, and each one suggests a different fix.

The first is decay: memory traces that are not used seem to weaken over time. Decay is hard to separate from other causes in experiments, but the everyday experience is familiar to anyone who has tried to recall a procedure they haven't performed in a year.

The second, and probably more important for workplace training, is interference. New learning can disrupt old memories, and old habits can disrupt new learning. Anyone who has switched to a new software system and kept clicking where the old button used to be has felt this. When training replaces a familiar process, interference is the main enemy, so practice should focus on the points where old and new differ.

The third is retrieval failure, where the memory may still exist but the cue that would bring it back is missing. Training that happens in a classroom, far from the real setting, can leave knowledge that people can't access on the job. Practicing in realistic conditions, with the same cues people will see at work, makes retrieval easier later.

What Slows the Forgetting Curve?

Several factors flatten the curve, and most of them are within a designer's or manager's control.

• Spaced review. Revisiting material after gaps, rather than all at once, produces much longer-lasting memory. This is the spacing effect, one of the most reliable findings in learning research.
• Retrieval practice. Pulling information out of memory, through quizzes, scenarios or explaining it to someone, strengthens it more than rereading.
• Meaning and connections. Material linked to real situations and to what learners already know is easier to keep.
• Depth of initial learning. Practicing until a skill is solid, not just until a single correct answer, slows later decline.
• Use on the job. Skills used regularly stay sharp. Skills used once a year fade, which is why rare, high-stakes procedures need planned refreshers.
• Sleep. Research on memory consolidation suggests sleep helps stabilize new learning, which is one argument against cramming a full day of new content.

How Do You Design Training That Beats the Forgetting Curve?

Design for the weeks after the course, not just the hour inside it. The practical plan below works well for most programs.

1. Teach less, practice more. Cut content that isn't needed for the job, and use the time for practice on realistic tasks.
2. Build retrieval into the course. Replace "click to read more" with questions and scenarios that make learners recall and apply.
3. Schedule spaced follow-ups. Plan short reviews a few days, a couple of weeks and a month or so after training. Each one can be a few scenario questions.
4. Provide a job aid. Not everything needs to be memorized. A checklist at the point of work carries the details so memory can focus on judgment.
5. Involve managers. A manager who asks about the new skill in a team meeting, or watches for it on the job, provides both retrieval and accountability.
6. Time the training. Deliver it close to when people will use the skill, so practice on the job begins before the curve drops too far.

The interactive model below shows how spaced reviews change a modeled forgetting curve. Try adding reviews at different intervals and watch how the curve flattens after each one.

The pattern you'll see in the model matches the research: each review lifts retention back up, and the next decline is slower than the last. If you want to plan that review schedule for a real program, our guide to spaced repetition training covers intervals, formats and what the evidence supports.

Which Skills Are Most at Risk?

Not all training fades at the same rate. The skills most vulnerable to the forgetting curve share a few traits:

A useful planning question for any course is, "How often will people use this between now and the next time we train them?" If the answer is "rarely," design the follow-up before you launch.

How Can You Measure Forgetting in Your Own Training?

You don't need a research lab, because a simple delayed assessment tells you most of what you need to know.

Give a short assessment at the end of training, then give a parallel version (same skills, different questions or scenarios) a few weeks later. The difference between the two scores is a rough measure of decline. If the delayed scores drop sharply on certain items, those skills need reinforcement or a job aid. If they hold steady, your design and the job itself are doing their work.

Better still, examine job performance data. Error rates, quality checks or observation checklists over the months after training show whether the skill survived contact with real work. That is the measure that matters most.

Working With the Forgetting Curve Instead of Against It

The forgetting curve shows that new learning fades quickly at first and then more slowly. Ebbinghaus measured it with meaningless syllables, so the exact numbers don't apply to workplace training, but the shape does. Forgetting is normal, and it is predictable enough to plan around.

The solution is not a longer course but a smarter schedule: practice that requires recall, reviews spaced over weeks, job aids for the details and managers who keep the skill in use.

Look at your next program's plan and check what happens after launch day. If the answer is "nothing," add two or three short spaced reviews, because that small addition can matter more than anything inside the course itself.

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