Glossary
Keystrokes per character (KSPC)
Keystrokes per character (KSPC) is the average number of keystrokes a text entry method needs to produce one character of text. A basic QWERTY keyboard scores 1, methods that need more presses score above 1, and word prediction can score below 1.
Updated October 16, 20263 cited facts, each traced to its source
Also called KSPC.
Keystrokes per character (KSPC) is the average number of keystrokes a text entry method needs to produce one character of text in a given language 1. Because it is a ratio, it compares methods on one scale, whatever the device.
KSPC is calculated from the keystrokes a method needs
To calculate KSPC, you describe how a method turns key presses into characters, then apply a language model to see how often each character and word occurs. The result is an average, so it can be worked out before anyone tests the method. I. Scott MacKenzie described the measure in a 2002 paper on text entry for mobile devices, where a single key often produces several letters.
The QWERTY keyboard is the baseline at 1
On a basic QWERTY keyboard each letter has its own key, so each keystroke produces one character, and the value is 1 2. A value above 1 means a method needs extra presses for each character. A value below 1 means one press produces more than one character, which is what word prediction does when a single key completes a whole word.
Typical values for English run from about 10 down to about 0.5
For English, the values in the paper run from about 10 for methods that use only cursor keys and a select key, down to about 0.5 for word prediction 3. The spread shows that the method, more than the language, sets the number of presses. A writer who switches from a keypad to a keyboard, or turns on word prediction, changes the KSPC of their typing even though the words stay the same.
What KSPC shows, and what it leaves out
KSPC counts presses, not time. Two methods with the same KSPC can produce different words per minute, because one may need more visual search or more thinking between presses. KSPC also ignores corrections unless they are counted as keystrokes.
For dictation the measure fits less neatly. A dictated word needs no key presses, so the keystrokes come only from corrections and punctuation typed by hand. A writer who dictates a draft and then fixes errors on the keyboard can see how many presses the fixes cost, and so judge how much the keyboard still contributes to the final text.
Related terms
- Words per minute (WPM): the usual unit of typing speed, counted in words rather than keystrokes.
- Keystrokes per hour (KPH): a count of key presses over time.
- QWERTY: the standard keyboard layout that serves as the KSPC baseline.
- Typing accuracy: the share of typed characters that are correct.
Guides that cover it
Evidence
Every number on this page, with where it comes from. Open a fact to see the exact words in its source.
- 1.KSPC is the number of keystrokes a text entry technique needs, on average, to generate one character of text in a given language.
I. Scott MacKenzie, Proceedings of the Fourth International Symposium on Human Computer Interaction with Mobile Devices (Mobile HCI 2002), LNCS 2411, Springer, 2002 · Original
- 2.For the basic QWERTY keyboard, MacKenzie's calculation gives a KSPC of 1.0000, because each letter has its own key and each keystroke produces one character.
I. Scott MacKenzie, Proceedings of the Fourth International Symposium on Human Computer Interaction with Mobile Devices (Mobile HCI 2002), LNCS 2411, Springer, 2002 · Original
- 3.For English, KSPC values across text entry techniques range from about 10, for methods that use only cursor keys and a select key, down to about 0.5, for word prediction techniques.
I. Scott MacKenzie, Proceedings of the Fourth International Symposium on Human Computer Interaction with Mobile Devices (Mobile HCI 2002), LNCS 2411, Springer, 2002 · Original
Related terms
- Typing Speed: Average WPM and How to Type FasterThe topic this term belongs to
- Articulation rateArticulation rate is the number of syllables a speaker produces per second, leaving out pauses. It measures how fast the speech itself comes out, so it is usually faster than the overall speaking rate that counts every pause.
- Characters per minute (CPM)Characters per minute (CPM) is the number of characters typed in one minute, counting spaces and punctuation. Words per minute is the same count divided by five, so a typist at 50 WPM enters 250 characters per minute.
- ColemakColemak is an alternative English keyboard layout, introduced in 2006 and designed for efficient, comfortable touch typing. Its supporters describe it as the third most popular layout for English touch typing, after QWERTY and Dvorak, but that ranking has no stated method.
- Dvorak Simplified KeyboardThe Dvorak Simplified Keyboard is an alternative English keyboard layout that places the most common letters on the home row. Dvorak and Dealey applied for a patent on it in 1932, but the studies that claimed it was faster than QWERTY have been criticized, and the evidence for a speed gain is weak.
- Home rowThe home row is the middle row of keys on a keyboard, where the fingers rest when you touch type. On a QWERTY keyboard it holds A, S, D, F for the left hand and J, K, L and semicolon for the right, and every other key is reached by moving a finger away from it and back.
- Hunt and peckHunt and peck is a typing method in which the typist finds each key by sight and presses it with one or two fingers, usually the index fingers. It is also called two-finger typing, and it differs from touch typing, which relies on memorized key positions and the home row.
- Keystroke dynamicsKeystroke dynamics is the identification of a person from the rhythm of their typing, using the timing between key presses as a pattern much like a handwritten signature. It is a behavioral biometric, so it supports identity checks through statistical matching rather than proving who typed.
- Keystrokes per hour (KPH)Keystrokes per hour (KPH) is the number of key presses made in one hour. It is the standard unit for numeric data entry, where many jobs require 8,000 or 10,000 keystrokes per hour, and it counts keys rather than words.
- Oral reading fluency (ORF)Oral reading fluency (ORF) measures how many words a reader gets right in one minute of reading a passage aloud. Schools record the result as words correct per minute (WCPM), which subtracts the words read wrongly from the total.
- QWERTYQWERTY is the standard letter arrangement on English keyboards, named for the first six letters of the top row. Christopher Latham Sholes devised it in the early 1870s for typewriters, and it is still the layout most people type on, even though faster layouts have been proposed.
- Rollover typingRollover, or key rollover, is the number of key presses a keyboard can detect when they overlap. Two-key rollover reliably detects only two keys at once, and a matrix keyboard without diodes can register a ghost key when three keys are pressed together.
- StenotypeA stenotype, also called a steno machine, is a chorded keyboard that stenographers use for shorthand, pressing several keys together to produce a syllable or word. The NCRA's court reporter skills test sets a speed of 225 words per minute, and voice writing is a newer method that uses speech recognition instead.
Pages that use this term
- Typing Speed: Average WPM and How to Type FasterTopic
- How Typing Speed Is Measured: WPM, Accuracy and TestsGuide
- How to Type Faster: What Actually Raises Your WPMGuide
- Phone Typing Speed: How Fast People Type on PhonesGuide
- Text Expanders and Autocomplete: Type Less, Not FasterGuide
- Typing Research: What Keystroke Data RevealsGuide
- Do word suggestions actually save typing time?Question
- How do you convert WPM to keystrokes per hour?Question
- How fast do people type in Japanese?Question
- Is swipe typing faster than tapping?Question
- What is a text expander and how much time does it save?Question
- Characters per minute (CPM)Glossary
- Keystroke dynamicsGlossary
- Keystrokes per hour (KPH)Glossary
- Rollover typingGlossary
- Typing accuracyGlossary