[Learn](/learn/) / Mac app methodology # How the PeakTock Mac app analyzes your typing PeakTock watches for the parts of typing that slow you down or cause mistakes. It learns your usual pace, then looks at each key and common two-key sequence. The result helps you see what to practise first. By PeakTock Updated August 17, 2026 The 20-second answer ## Your typing becomes focused practice PeakTock measures your speed, accuracy, and consistency. It compares them with your normal typing and becomes more confident as it collects examples. It then uses weak keys and key pairs to suggest focused practice. 1. 01 **Everyday typing** Keys, pairs, and words 2. 02 **Measurements** 40% speed · 30% accuracy · 30% consistency 3. 03 **Mastery** A personal score from 0 to 100 4. 04 **Guidance** Practice based on your patterns ## 1\. What PeakTock measures A **[key](/learn/keys/)** is one button you press, such as A or Space. A **[key pair](/learn/bigrams/)** is two keys that you type one after the other. For example, the word _the_ contains the pairs t \+ h and h \+ e. A [trigram](/learn/trigrams/) joins three keys, such as t \+ h \+ e. PeakTock does not currently report a separate trigram score. A key can feel easy on its own but slow you down after another key. This is why PeakTock measures both single keys and key pairs. Every recorded example is an **observation**. More observations give the app a better picture of your normal typing. For each key or pair, PeakTock looks at three parts of your typing: 1. 01 **Speed** How quickly you type the key or pair compared with your usual pace. 2. 02 **Accuracy** How often you type it correctly. 3. 03 **Consistency** How similar your timing is each time you type it. ## 2\. How your mastery score works ### What the score means PeakTock gives each measured key, key pair, and word a mastery score from 0 to 100\. A higher score means that you usually type it quickly, correctly, and at a steady pace. A lower score marks an item to compare before you choose a practice target. Mastery is not the same as words per minute, and it does not rank you against other people. PeakTock compares your typing with your own usual pace. Your score can improve when you become faster, make fewer mistakes, type more steadily, or provide enough examples for a firmer result. ### Mac app or web test? Mac app **Your behavior over time** Uses your speed, accuracy, and consistency during everyday typing. Free web test **Difficulty in one test** Uses one fixed US-QWERTY allowance for each key. [Read how the web typing test works](/learn/typing-test-methodology/) ### How the three measurements are combined Speed has the largest effect on the score. Accuracy and consistency have equal weight: mastery = **40% speed** \+ **30% accuracy** \+ **30% consistency** PeakTock converts the three measurements to comparable values and limits the final score to the 0–100 range. It then lowers the strength of an early result when it has seen only a few examples. One unusually good or bad attempt cannot produce a firm score. __Inputs to the Mac key and key-pair mastery score__ | Input | Weight | How it is calculated | | ----------- | ------ | ---------------------------------------------------------------------------------- | | Speed | 40% | Your timing for the key or pair compared with your usual timing. | | Accuracy | 30% | The number of correct attempts divided by all attempts. | | Consistency | 30% | How much the timing changes between attempts. Similar timings give a higher score. | ### Why your speed score is personal PeakTock compares the timing for a key or pair with your personal average. It smooths the timing so that one interruption does not have too much effect. Faster-than-usual typing raises the speed part of the score. Slower-than-usual typing lowers it. A new profile starts with a temporary timing estimate of 200 milliseconds, or one fifth of a second. PeakTock replaces the influence of that estimate as it learns from your typing. It does not expect every person to type at one fixed speed. ## 3\. How PeakTock builds a reliable score ### Why new scores start cautiously Five examples cannot tell PeakTock as much as fifty examples. The app therefore reduces the effect of a score when it has little evidence. This avoids strong conclusions from a pattern that you have typed only a few times. __When PeakTock has enough evidence__ | Result | Evidence | | --------------------------------- | --------------- | | Confidence starts growing | 15 observations | | A key pair can affect a key score | 20 observations | | Key-pair mistake guidance | 20 observations | | Finger-pattern guidance | 40 presses | | Low-accuracy guidance | 50 presses | ### How key pairs affect a key score PeakTock first scores the pairs that end with the same key. Pairs you type often have more effect than rare pairs. This makes the key score reflect the way you normally reach that key in words and sentences. If no pair has reached 20 observations, PeakTock calculates a cautious score from the key's own speed, accuracy, consistency, and number of examples. You do not need to wait for a large pair history before the key appears in your results. ### Why words use a separate formula PeakTock also scores complete words, such as _because_ or _keyboard_. For a complete word, PeakTock knows the speed and accuracy but does not have enough detail to measure every key inside it. Word mastery therefore uses a different formula: word mastery = (0.57 × speed + 0.43 × accuracy) × evidence confidence × 100 Words have their own personal speed baseline. Typing a complete word includes movement between several keys, so a single-key baseline would not be a fair comparison. **Show the technical details** The exact formulas for speed, confidence, and mastery key or pair mastery = (0.40 × speed + 0.30 × accuracy + 0.30 × consistency) × evidence confidence × 100 speed = 2 ÷ (1 + e2 × (item timing − personal average) ÷ personal average) evidence confidence = 1 ÷ (1 + e−0.2 × (observations − 15)) Consistency is one minus the amount of timing variation relative to the average timing. When there is not enough timing data, PeakTock uses a neutral consistency value. ## 4\. How PeakTock turns scores into guidance ### How PeakTock finds a possible cause A low score tells you where to look. PeakTock then checks the recorded typing for a possible reason: - **Low accuracy:** a key stays below 95% after at least 50 presses. - **Key-pair mistakes:** the movement from one key to the next has more than 5% errors after at least 20 observations. - **Hesitation:** a key takes more than 1.5 times your overall average after at least 20 timings. - **Mistakes at higher speeds:** your accuracy drops when your typing pace rises. - **A finger pattern:** the measured accuracy for one finger stays below 95% after at least 40 presses. A finger result comes from your own measured typing. PeakTock does not assume that a certain finger is weak only because of its position on the keyboard. ### Recent results and your longer history PeakTock keeps a long-term mastery score and a seven-day recent view. The long-term score shows the broader pattern. Recent mastery reacts faster when your typing changes. This lets the app notice improvement or a setback without discarding the history that made the score stable. PeakTock also keeps results separate when you change the keyboard language or layout selected in macOS. For example, it does not mix a German keyboard layout with a US keyboard layout. ## 5\. Limits and common questions ### What this model does not prove - **It is not a ranking against other typists.** Most speed judgments use your own usual pace. - **Early scores can change quickly.** A small number of examples cannot support a firm conclusion. - **Context can affect timing.** Keyboard hardware, fatigue, injury, application behavior, and interruptions can change a session. - **One score can hide detail.** Two equal mastery scores can come from different mixes of speed, accuracy, and consistency. - **The limits are coaching rules.** They help PeakTock give consistent advice. They are not medical or ergonomic standards. ### Common questions #### Does the Mac app use the same score as the free web typing test? No. The Mac app learns from your own speed, accuracy, and consistency during everyday typing. The web test uses a fixed US-QWERTY allowance for each key. Each method has a different purpose. #### Is a 100 mastery score the same as 100 words per minute? No. Words per minute measures your overall typing speed. Mastery is a score from 0 to 100 for a specific key, key pair, or word. It combines your speed, accuracy, consistency, and the amount of typing PeakTock has seen. #### How much typing does PeakTock need before it trusts a key pair? PeakTock needs at least 20 examples of the same key pair before that pair can affect the key score. A new score stays cautious while the app collects those examples. #### Why can a mastery score change even when I make no errors? Accuracy is only one part of mastery. The score can also change when you become faster, your timing becomes steadier, or PeakTock collects more examples. The app also adjusts its idea of your normal pace as you type more. --- Canonical HTML: