Spaced Repetition Calculator (SM-2)
Enter the recall quality of each review (0–5) and watch the SM-2 algorithm compute your easiness factor and next interval — exactly as published by SuperMemo.
How intervals are computed: grades below 3 restart the schedule without changing the easiness factor; grades 3+ set intervals to 1 day, then 6 days, then previous interval × easiness factor (rounded to whole days). This matches the official SM-2 description — many online calculators get the failure case wrong.
Exam Countdown & Study Planner
Enter your exam date and topics. The planner spreads first-study sessions across your available days and schedules SM-2 reviews — never on or after the exam date. Download the result as a calendar file. It doubles as an exam countdown & planner: each day shows exactly what is due, counting down to exam day.
Honest scope: the plan assumes a constant recall quality (default 4 = good recall). Real learning varies — treat the schedule as a plan, not a prediction. Sessions that would fall on or after your exam date are dropped and listed openly.
Forgetting Curve Visualizer
Explore Ebbinghaus's forgetting curve: retention decays exponentially without review. Each review (orange dashed line) resets retention and grows memory stability, so intervals can stretch.
Simplified model: R = e^(−t/S). Real memory is messier — this illustrates why spaced intervals grow, not a measurement of your brain.
What is spaced repetition?
Spaced repetition is a study technique that schedules reviews at increasing intervals — instead of re-reading everything every day, you review each item right before you would forget it. Each successful recall strengthens the memory, so the next interval can be longer. It directly exploits the forgetting curve: without review, retention collapses exponentially within days; with well-timed reviews, it stays high for months.
Use it as a spaced repetition tracker for anything you must remember long-term: exam syllabi, vocabulary, anatomy, legal cases, or formulas. The planner above doubles as your tracker — every session is a checklist item with a date.
The SM-2 spaced repetition formula
SM-2, created by Piotr Woźniak for SuperMemo, is the most widely implemented spaced repetition algorithm. After each review you grade recall quality q from 0 (blackout) to 5 (perfect). The easiness factor updates as:
EF′ = EF + (0.1 − (5−q) × (0.08 + (5−q) × 0.02)), floored at 1.3
| Quality q | Meaning | What happens |
|---|---|---|
| 5 | Perfect recall | EF +0.10, interval grows fastest |
| 4 | Correct after hesitation | EF unchanged, interval grows |
| 3 | Correct with serious difficulty | EF −0.14, interval grows slowly |
| 2 | Wrong, but answer felt familiar | Schedule restarts (EF unchanged) |
| 1 | Wrong, remembered the right answer | Schedule restarts (EF unchanged) |
| 0 | Complete blackout | Schedule restarts (EF unchanged) |
Spaced repetition intervals, explained
With default easiness (2.5) and solid recall (q=4), SM-2 generates the classic interval sequence:
| Review # | 1 | 2 | 3 | 4 | 5 |
|---|---|---|---|---|---|
| Next interval | 1 day | 6 days | 15 days | 38 days | 95 days |
Notice the pattern: 1 → 6 → ×2.5 → ×2.5. This is why fixed-interval schedules (review every 7 days) waste effort — easy items get over-reviewed while hard items are forgotten. The calculator above personalizes the spaced repetition intervals to your actual grades.
Spaced repetition schedule generator
The Study Planner tab is a full spaced repetition schedule generator — and more generally a spaced repetition generator for any study plan: give it your exam date and topic list, and it produces a day-by-day spaced repetition timetable — which topics to learn each day, and exactly when each topic comes back for review. It respects two constraints real students need:
- Exam cutoff: no review is ever scheduled on or after the exam date.
- Daily review cap: overloaded days spill over to the next free day instead of piling up.
Your generated spaced repetition plan works as a countdown: every day shows what's due, counting down to the exam.
Spaced repetition calendar & reminders
A schedule only works if you see it. Click Download .ics to export your plan as a standard calendar file and import it into Google Calendar, Apple Calendar, or Outlook. Each learning session and review becomes an event — a built-in spaced repetition reminder system with zero extra apps. The file uses the open iCalendar format, so it works everywhere.
Spaced repetition template (printable & Notion)
Prefer paper or Notion? Your generated plan is a spaced repetition schedule template: print the day-by-day table and check sessions off, or paste it into a Notion table for a DIY spaced repetition template in Notion — add a checkbox column and a "next review" date column, and you have a tracker that rivals paid apps. If you searched for a spaced repetition template notion setup, this is the fastest honest path: generate the schedule here, paste it into Notion, done. No proprietary format, no lock-in.
Spaced repetition planner vs the alternatives
| This planner | mrcalcu | glasp | Pearson | Anki | |
|---|---|---|---|---|---|
| SM-2 calculator | ✅ verified vs spec | ✅ | ❌ (fixed intervals) | ❌ | ✅ (in-app) |
| Exam-date schedule generator | ✅ | ❌ | partial | ❌ | ❌ |
| Calendar (.ics) export | ✅ | ❌ | ✅ | ❌ | ❌ |
| Forgetting curve visualizer | ✅ | ❌ | ❌ | ✅ | ❌ |
| No signup / install | ✅ | ✅ | ❌ | ✅ | ❌ |
| 100% client-side | ✅ | ✅ | ❌ | ✅ | ✅ |
Comparison checked October 2026. No single competitor combines all three tools — that is the gap this planner fills.
Privacy
This tool is 100% client-side. Your topics, exam date, and schedule are computed in your browser and never sent to any server — block all network requests and everything keeps working.
Frequently asked questions
What is spaced repetition?
Spaced repetition is a learning technique where reviews are spread out over increasing intervals of time instead of crammed into one session. Each successful recall strengthens the memory, so the next review can wait longer. It is based on the forgetting curve discovered by Hermann Ebbinghaus: without review, retention drops exponentially; with well-timed reviews, long-term retention rises dramatically.
How does the SM-2 algorithm work?
SM-2, developed by Piotr Wozniak for SuperMemo, tracks an easiness factor (EF) per item starting at 2.5. After each review you grade recall quality from 0 to 5. Grades below 3 restart the schedule without changing EF; grades 3 and above set the next interval to 1 day, then 6 days, then the previous interval multiplied by EF. EF itself is adjusted after every successful review and never drops below 1.3.
What is the SM-2 formula?
The SM-2 easiness factor update is: EF' = EF + (0.1 - (5-q) * (0.08 + (5-q) * 0.02)), where q is the recall quality from 0 to 5. Intervals follow I(1)=1 day, I(2)=6 days, and I(n)=I(n-1)*EF for n>2. This calculator implements the formula exactly as published.
What do the quality grades 0-5 mean in SM-2?
0 = complete blackout, 1 = incorrect response but the correct one remembered, 2 = incorrect response but the correct one seemed familiar, 3 = correct response recalled with serious difficulty, 4 = correct response after some hesitation, 5 = perfect recall. Grades 0-2 restart the item's schedule; grades 3-5 advance it.
What are the standard spaced repetition intervals?
With the default easiness factor of 2.5 and good recall (quality 4), SM-2 produces intervals of 1, 6, 15, 38 and 95 days. Easier items (quality 5) stretch further; harder items (quality 3) shrink. The exact sequence depends on your grades, which is why a calculator beats a fixed schedule.
Does spaced repetition actually work?
Yes — it is one of the most replicated findings in learning science. Cepeda et al.'s 2006 review of 254 studies found spaced practice consistently outperforms massed practice (cramming), with the advantage growing as the retention interval grows. It works because each spaced retrieval strengthens the memory trace more than an immediate re-read.
Is spaced repetition better than cramming?
For anything you need to remember longer than a day or two, yes. Cramming can work for a test tomorrow, but retention collapses within days. Spaced repetition trades a little extra scheduling effort for durable memory — ideal for exams weeks away, language learning, and medical or law school.
How do I make a spaced repetition study plan for an exam?
Enter your exam date and your topics in the Study Planner tab above. The tool spreads first-study sessions across your available days and schedules each topic's reviews at SM-2 intervals (1, 6, 15, 38 days), never placing a review on or after the exam date. You can cap daily reviews so no day is overloaded, then export everything to your calendar.
Can I export my study schedule to Google Calendar or Apple Calendar?
Yes. After generating a plan, click Download .ics to get a standard iCalendar file. Import it into Google Calendar, Apple Calendar, or Outlook — each learning session and review becomes a calendar event, which doubles as your spaced repetition reminder system.
What is the forgetting curve?
The forgetting curve, discovered by Hermann Ebbinghaus in the 1880s, describes how memory retention decays exponentially over time without review: R = e^(-t/S), where S is memory stability. Each successful review resets retention and increases stability, which is why intervals can grow. The visualizer tab above lets you explore this interactively.
How is this different from Anki?
Anki is a full flashcard app you install and commit to daily; this is a lightweight planner you use once. Use this tool to generate an exam study schedule or check SM-2 intervals, then study however you like — including inside Anki. No signup, no sync, no daily app habit required.
How is this different from other spaced repetition calculators?
Most calculators do one thing: mrcalcu computes SM-2 intervals for a single card, glasp uses fixed (non-adaptive) intervals, and Pearson's tool only draws the forgetting curve. This planner combines all three — a verified SM-2 calculator, an exam-date schedule generator with calendar export, and a forgetting curve visualizer — in one page.
Do I need to sign up or install anything?
No. The planner runs entirely in your browser. There is no account, no signup, and nothing to install. Your topics and schedule never leave your device.
Is my study data private?
Yes. This tool is 100% client-side: all computation happens in your browser and nothing you type is sent to any server. You can verify this by blocking network requests — the tool keeps working.
Can I use spaced repetition for language learning?
Absolutely — vocabulary is the classic use case. Learn new words in small daily batches and let the SM-2 schedule bring them back at 1, 6, 15 and 38 days. The planner tab works the same way: put word sets in as topics and it will space their reviews for you.