Calculation methods
The formulas, worked examples, assumptions and limits behind every tool.
Speed test ↗
WPM = correctly aligned final characters ÷ 5 ÷ active minutes. Accuracy compares the final typed text with the target.
Example: 250 correctly aligned characters in 60 active seconds equal 50 WPM.
The clock starts only when you press Start. Hiding the page pauses the session. Backspaces are not counted as separate errors; paste and drop are disabled in the typing area.
Custom passage ↗
The same final-text alignment scoring is used for both languages. WPM always means five characters per word; CPM is also shown.
Example: 100 correct characters in 30 seconds equal 200 CPM and 40 five-character WPM.
Maximum 3,000 Unicode characters. The custom passage itself is not saved in history. It remains in memory for the current page only.
Problem keys ↗
Selected letters are drawn with a seeded generator into five-letter groups. Historical errors count mismatched final letter positions.
Example: Choose A, S, D, F, J and K to practise home-row keys without a remote text service.
This is a synthetic letter drill, not an AI-generated story. Only A–Z keys are accepted. No key events are observed outside the typing control.
Local progress ↗
Up to 100 completed sessions are retained in this browser. The chart displays recent WPM; summaries report session averages.
Example: A 40-WPM session and a 60-WPM session have a session-average of 50 WPM, regardless of duration.
History stores scores, timing and letter-error counts, not your custom passage. Browser storage can be cleared by the browser; JSON backups are portable.
Units and numerical limits
Conversions use 1 inch = 2.54 cm, 1 mile = 1.609344 km, and 1 avoirdupois ounce = 28.349523125 g. Empty, non-finite, out-of-range and unsupported values are rejected. Displayed values are rounded; calculations retain precision. Input-specific limits are reported alongside the field when exceeded.