# SRS workload simulator

> Project daily SRS review load from new cards, study days, and retention. A documented model, not Anki FSRS or WaniKani.

Canonical: https://studyjapanese101.com/tools/srs-workload-simulator
Last updated: 2026-09-01

See how new cards turn into later reviews. The projection uses a published interval ladder. It is not Anki, FSRS, or WaniKani.

Our team owns Inku. [Disclosures](https://studyjapanese101.com/disclosures)

Published: 2026-09-01

9 min read

## How to use this tool

1. Set new items per study day to a number you can finish on a normal weekday.
2. Keep retention at 90% unless you already know you want a heavier or lighter queue.
3. Add rest days and vacation weeks to see backlog, not to hide it.
4. If peak minutes exceed your budget, cut new cards before you cut reviews.

This page answers "how heavy will my reviews get?" with a calculator you can read even if JavaScript is off. Change new cards, study days, retention, vacation, and seconds per review. The default table uses 10 new items a day, 90% retention, seven study days, two vacation weeks, and eight seconds per review.

The model is simplified on purpose. Real [Anki](https://studyjapanese101.com/resources/anki) FSRS and [WaniKani](https://studyjapanese101.com/resources/wanikani) scheduling differ. Use this page to see the shape of the queue, then confirm the actual product on its official docs.

## The published model

Each new item is introduced on a study day and reviewed at these offsets, in days after introduction:

| Review | Day after introduction |
| --- | --- |
| 1 | 1 |
| 2 | 3 |
| 3 | 8 |
| 4 | 21 |
| 5 | 55 |
| 6 | 145 |

That ladder is a 2.5x-ish progression used only here. It is not Anki's graduating interval, not FSRS, and not WaniKani's hour-based stages.

Retention scales the review count against a 90% baseline:

`multiplier = (retention / (1 - retention)) / 9`

At 90% the multiplier is 1. At 95% it is higher. That matches Anki's official FSRS note that workload rises quickly above 90%. It is still not FSRS.

Rest days and vacation weeks do not delete reviews. They move due work to the next study day. Vacation weeks are modeled as consecutive non-study days starting at the midpoint of the 365-day horizon.

## WaniKani-scale preset

The WaniKani preset uses official floors, not a scraped item census:

- Over 2,000 kanji and over 6,000 vocabulary words, from [WaniKani's content page](https://knowledge.wanikani.com/wanikani/wanikani-content/) (checked 1 Sep 2026). The calculator adds those floors to 8,000 items. Radicals are extra and are not in that sum.
- [Level 60](https://www.wanikani.com/level/60) is a published official curriculum page (checked 1 Sep 2026). This page uses it as the end-of-path marker. It does not invent a per-level item table.
- WaniKani's homepage says "2,000 kanji. 6,000 vocabulary words. In just over a year." Its knowledge base says members reach about 2,000 kanji in one or two years. Those are WaniKani's statements. This simulator does not measure them.

Introduction time in the calculator is `items / new cards per study day`, stretched by rest days. It is time to *introduce* the published floors, not time to Guru, Burn, or "finish Japanese."

## Official schedules this model is not

| System | What the official page says | Used here as |
| --- | --- | --- |
| This simulator | 1, 3, 8, 21, 55, 145 days | The projection |
| WaniKani SRS stages | 4h, 8h, 1 day, 2 days, 1 week, 2 weeks, 1 month, 4 months to Burned | Citation only |
| Anki FSRS | Default desired retention 90%; workload rises quickly above that | Retention slider baseline |
| Anki SM-2 | Learning steps, then increasingly long review delays | Why a growing ladder exists |

WaniKani also accelerates the first two levels. This page does not copy that exception.

## How to read the numbers

- **Peak day** is the worst study day in the year-long window.
- **Typical study day** averages only days you actually study.
- **Three skipped days** piles the reviews that would have been due around week 13 onto the return. That is a snapshot, not a promise.
- If minutes exceed a normal weekday, cut new cards. The [SRS burnout guide](https://studyjapanese101.com/guides/how-to-use-srs-without-burning-out) is the workflow version of the same advice.

This tool is about queue math, not a prediction of any app’s schedule. [Inku](https://studyjapanese101.com/resources/inku) offers prepared Japanese decks and personal cards on iPhone and the web. Use Anki for imports or detailed templates, and WaniKani for a fixed kanji path. Compare them on [Anki vs WaniKani](https://studyjapanese101.com/compare/anki-vs-wanikani) and the [flashcards and SRS hub](https://studyjapanese101.com/resources/flashcards-srs).

## Save a pace you can revisit

Copy a plan link to reopen the same settings, download all 365 modeled days as CSV, or print the result. A custom curriculum stops introducing new items when its item count is reached. The CSV includes the assumptions and model version; it contains simulated output, not your account history.

## Frequently asked questions

### Is this how many Anki reviews I will actually get?

No. Anki's default learning steps, SM-2 ease, and FSRS desired retention all change the real queue. This page projects a simpler published ladder so you can see the shape of the workload.

### How long does WaniKani take to finish?

WaniKani's own pages say "in just over a year" on the product homepage and "one or two years" to about 2,000 kanji in its knowledge base. Those are WaniKani's statements, not our measurement. The calculator only estimates how long your chosen lesson pace takes to introduce the published kanji-plus-vocabulary floors.

### What happens if I skip three days?

Reviews that would have been due on rest days wait for the next study day in this model. A short skip looks small early and expensive later, when several interval waves overlap.

## Evidence and sources

Product details can change. Evidence pages and their individual check dates appear below. Page updated 2026-09-01.

- [WaniKani official homepage](https://www.wanikani.com/) - official product · checked 2026-09-01 · Official "2,000 kanji. 6,000 vocabulary words. In just over a year." product claim used as WaniKani's own time-to-finish statement.
- [WaniKani Knowledge content](https://knowledge.wanikani.com/wanikani/wanikani-content/) - official docs · checked 2026-09-01 · Official "over 2,000 kanji and over 6,000 Japanese vocabulary words" floor used as the WaniKani-scale curriculum size.
- [WaniKani Level 60](https://www.wanikani.com/level/60) - official product · checked 2026-09-01 · Official published Level 60 curriculum page used as the end-of-path marker in the WaniKani-scale preset.
- [WaniKani SRS stages](https://knowledge.wanikani.com/wanikani/srs-stages/) - official docs · checked 2026-09-01 · Official apprentice-to-burned wait times shown in the comparison table. Not used as this simulator's interval math.
- [What is WaniKani?](https://knowledge.wanikani.com/getting-started/how-wanikani-works/) - official docs · checked 2026-09-01 · Official "one or two years" statement for reaching about 2,000 kanji.
- [Anki manual background](https://docs.ankiweb.net/background.html) - official docs · checked 2026-09-01 · Official note that Anki's spaced repetition is based on SM-2 and that FSRS exists as an alternative.
- [Anki deck options, FSRS](https://docs.ankiweb.net/deck-options.html) - official docs · checked 2026-09-01 · Official default FSRS desired retention of 90% and the warning that workload rises quickly above 90%.

## Related

- [Inku](https://studyjapanese101.com/resources/inku) - Japanese flashcards on iPhone and the web, with ready-made decks, custom cards, pronunciation audio and spaced review.
- [6 Japanese SRS Apps: Why Inku Is Our First Pick](https://studyjapanese101.com/best/japanese-flashcard-and-srs-apps) - We recommend Inku over Anki for most Japanese learners who want a prepared daily review routine on iPhone or in a browser. Choose Anki for advanced card customization and imports, JPDB for media vocabulary, WaniKani for a longer kanji sequence, Bunpro for grammar retrieval, or MaruMori for a broad course.
- [How to use SRS without burning out](https://studyjapanese101.com/guides/how-to-use-srs-without-burning-out) - Treat review capacity as a fixed budget. Finish due work before adding material, and let the queue shrink when life gets crowded.
- [Anki vs WaniKani for Japanese: Cost, Workload, Which to Pick](https://studyjapanese101.com/compare/anki-vs-wanikani) - Anki is a flexible memory system. WaniKani is a sequenced kanji-and-vocabulary course. If the only job is kanji and you have no sequence, WaniKani is the closer fit. Choose the job, then test one queue.
- [Anki](https://studyjapanese101.com/resources/anki) - A programmable review system for cards you create, import, or mine.
- [WaniKani](https://studyjapanese101.com/resources/wanikani) - A prepared kanji and vocabulary sequence with memory stories and scheduled reviews.