CPM and KPH, and How They Relate to WPM
CPM is WPM multiplied by five, and KPH is CPM multiplied by sixty, which means 40 words per minute, 200 characters per minute and 12 000 keystrokes per hour all describe exactly the same pace. Three units survive for the same measurement because three different industries adopted them separately, and none of them is more correct than the others.
The three units, defined precisely
WPM, words per minute, counts a word as five characters including the space that follows it. The convention exists so that a passage of long words and a passage of short words can be compared, and it is explained in what WPM means.
CPM, characters per minute, drops the fiction of the word and counts characters directly. It is the unit in German language material, where it appears as Anschläge pro Minute, and the same idea carries other names elsewhere: pulsaciones por minuto in Spanish, toques por minuto in Portuguese, aanslagen per minuut in Dutch and frappes par minute in French.
KPH, keystrokes per hour, is CPM scaled up by sixty. It belongs to data entry and clerical recruitment, where requirements are written as 8 000, 10 000 or 12 000 KPH.
Converting in your head
Two steps cover every case. Divide KPH by 60 to reach CPM, then divide CPM by 5 to reach WPM. Dividing KPH by 300 goes straight from an advert to a test result.
- 8 000 KPH is 133 CPM, about 27 WPM.
- 10 000 KPH is 167 CPM, about 33 WPM.
- 12 000 KPH is 200 CPM, 40 WPM exactly.
- 15 000 KPH is 250 CPM, 50 WPM exactly.
Going the other way, multiply your WPM by 300. A steady 45 WPM is 13 500 KPH, which is a figure worth knowing before you decide an advert is out of reach. The same ladder appears from the other side in average typing speed.
Why the hour in KPH is theoretical
A keystroke per hour figure is almost never measured over an hour. It comes from a short test, usually one to five minutes, and is multiplied out. That arithmetic assumes an unbroken hour with no reading, no thinking, no reaching for a form and no pause, which describes nobody's working hour.
This is not dishonesty, it is a unit convention, and it matters in one practical way. An employer asking for 12 000 KPH is asking you to demonstrate 200 CPM in a short test, not to sustain it for sixty minutes. Treat the figure as a pace, not as a quota.
Four ways a comparison goes wrong
The units are simple. Comparing figures across sources is where the damage happens.
1. Different denominators. A number quoted in KPH looks three hundred times larger than the same performance in WPM, which makes an advert sound like it wants a specialist when it wants ordinary office typing. 2. Correct characters against all characters. Some tools count only the characters that matched the source text, others count every key you pressed. The second definition produces a higher number from identical typing. 3. Spaces counted or not. The five character word includes the trailing space. A tool that excludes spaces reports a lower CPM for the same passage, by roughly one character in six for English prose. 4. Field navigation counted as keystrokes. Numeric data entry moves between fields with Tab and Enter, and where those presses are counted, a KPH figure from a data entry test is not comparable with one derived from typing prose.
The details of what starts the clock and what a backspace does are covered in how typing speed is measured, and they explain most of the remaining gaps between two sites.
What our test reports, and in which unit
Our typing test shows the result in all three units at once, calculated from the characters that matched the source: words per minute, characters per minute, and keystrokes per hour as the CPM figure multiplied by sixty. Beside them sits a raw words per minute figure counting every character you typed, whether it was right or not, and a count of the corrections you made along the way.
Two numbers from one run therefore answer two different questions. The raw figure describes how fast your hands moved. The main figure describes how much correct text you produced. Recruitment cares about the second, which is also the one that changes when accuracy improves rather than when effort increases.
For a run where the character count is easy to reason about, type the Preamble to the United States Constitution, the single sentence that opens the document and states what the whole thing is for. It carries a capital letter on almost every noun, so your left hand works the Shift key constantly, and the CPM figure it produces will sit below your usual pace for exactly that reason.