How Many Hours a Day Should You Study? What the Research Says (and the 40/60 Split That Matters More)

You plan a 10-hour study Saturday. Snacks ready, phone in a drawer, color-coded schedule. By evening you've done maybe two hours of real work, and, as one student on r/GetStudying put it, "8 hours of looking like i was studying."

So how many hours a day should you study? It comes up on study forums all the time, and the honest answer is that nobody has found a magic number. What the research does show is that total hours predict your grades surprisingly weakly. What you do inside those hours predicts a lot more.

Do more study hours mean better grades?

Not by themselves.

A 2005 study by psychologist E. Ashby Plant and colleagues at Florida State University, including the expertise researcher Anders Ericsson, asked exactly this. Why does the amount students study do such a poor job of predicting their GPA? Their answer, published in Contemporary Educational Psychology, was that study time only became a significant predictor of GPA once they also accounted for the quality of studying and how well students had done before. Hours on their own didn't tell you much.

An even bigger study points the same way. In a 2019 paper in the Journal of Human Resources, economist Philip Oreopoulos and colleagues randomly assigned more than 9,000 students at three colleges to build a weekly study schedule online, then sent them study reminders or coaching by text. Students engaged, and at two of the colleges they studied slightly more. The effect on their grades, credits and whether they stayed in college was zero.

Getting students to schedule more hours didn't move their results. That's a big clue that the hours aren't the main thing.

Why your 10-hour study day turns into 2 hours

Part of it is attention. Nobody can concentrate hard for ten hours, and the hours after the first few tend to fill up with breaks that get longer, rereading the same page, and checking your phone between paragraphs. We covered what that kind of marathon does to memory in our post on studymaxxing.

The bigger part is what those hours are spent on. Rereading notes, highlighting, rewatching a lecture. It feels productive because it gets easier each time, and that ease tricks you into thinking you know the material, the illusion of competence.

A 2006 study by Henry Roediger and Jeffrey Karpicke at Washington University in St. Louis shows how misleading that feeling is. Students read prose passages and then either reread them or took recall tests on them without feedback. On a test five minutes later, rereading won. But on tests two days and a week later, the students who had tested themselves remembered substantially more. And the rereaders felt more confident they'd remember it.

So a day of rereading can be long, tiring and mostly wasted, while feeling like a great study day.

The 40/60 split: a 100-year-old study on reading vs reciting

In 1917, Arthur Gates ran one of the first experiments on this question for his PhD at Columbia University. He had pupils at a school in Oakland, California, memorise short biographies and lists of nonsense syllables. Some only read the material over and over. Others split their time between reading and recitation, which meant looking away from the page and trying to say it from memory.

The best mix clearly beat reading alone. For the biographies, the best results came from spending about 40% of the time reading and the rest reciting. That combination beat pure reading by roughly 30% on an immediate test, and the gap was nearly twice as large when pupils were tested again three or four hours later. Older pupils also handled reading-heavy mixes better than younger ones did.

Recently a student on r/studytips shared what they call a 65/35 rule, which means spending less time reading than proving you learned it. That's almost exactly what Gates found a century ago.

Does the 40/60 split work for adults?

The exact ratio is shakier. In 2014, Kathleen McDermott and Farah Naaz ran four experiments modelled on Gates's design with adults, and found no consistent benefit from recitation in that setup.

But the bigger idea, that pulling information out of your head beats putting it back in, holds up well for college students. That's what the Roediger and Karpicke study above found, and it's the idea behind the testing effect. So treat 40/60 as a direction, not a law. If most of your study time is reading, flip it so most of it is testing.

So how many hours should you actually study?

Here's a practical way to set your own number instead of copying someone's 10-hour routine.

1. Start from what you need to cover

List the topics for your next exam and mark each one as solid, shaky or unknown. Your study time is however long it takes to get the shaky and unknown ones to solid. That might be 90 minutes a day for one class and three hours for another.

2. Work in focused blocks

Use blocks of 25 to 50 minutes with real breaks in between. The Pomodoro Technique is the classic version. Count blocks, not hours. "Four good blocks" is a better daily goal than "eight hours at the library."

3. Use the 40/60 split inside each block

In a 50-minute block, spend about 20 minutes reading or making notes and 30 minutes producing answers. That means practice questions, flashcards answered out loud, explaining it to an empty room, or the blurting method, where you write down everything you remember on a blank page and then check.

4. Track output, not time

At the end of the day, don't ask how long you studied. Ask how many questions you answered, how many blank pages you filled, or how many topics moved from shaky to solid. If you got two hours of that, it was a good day.

Our honest take: if you're doing three or four focused blocks of mostly self-testing on a school day, you're doing more than most people who claim eight hours.

FAQ

How many hours a day should a college student study?

There's no research-backed number, and it depends on your course load and how close your exams are. The Florida State study and the 9,000-student experiment both found that hours alone barely predict results. Set your time by what you need to cover, then make most of it self-testing.

Is studying 10 hours a day too much?

For most students, yes. Concentration drops long before hour ten, and extra hours spent rereading add little. A few focused, testing-heavy blocks beat a long day of rereading.

Do top students study less?

The research doesn't say they study less. It says hours alone don't predict who does well. Students who get good results tend to study in ways that make each hour count.

What is the 40/60 study split?

It comes from a 1917 study by Arthur Gates, where the best results came from spending about 40% of study time reading and the rest trying to recall the material from memory. For adults, use it as a direction. Spend more of your time testing yourself than rereading.

Plan tomorrow in blocks, not hours

Tonight, write down tomorrow's study as blocks instead of hours. Three or four of them. For each one, write what you'll read first and how you'll test yourself for the rest of the block.

If testing yourself is the part you keep skipping because making questions takes too long, StudyLab can turn your notes or slides into a practice quiz, so the 60% part of each block is ready to go.