estimateReadingTime — GTM Variable Template for GTM

VARIABLES › GTM

estimateReadingTime CORE GTM

Direct (.tpl) Apply (.tpl)

Estimates the reading time of content based on word count.

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When to Use This

Date & Time

Calculate durations, differences, and time-based operations on date values.

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Examples

Default reading time▶ Try

INPUT

Word Count: 700
Words Per Minute: undefined
Minimum Seconds: undefined

OUTPUT

120

Invalid input returns undefined▶ Try

INPUT

Word Count: not a number
Words Per Minute: undefined
Minimum Seconds: undefined

OUTPUT

undefined

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GTM Configuration

This is what you'll see when you open this variable in Google Tag Manager. Hover the icons for details.

estimateReadingTime

Read-Only Try Live

Word Count

💾 The total number of words to base the estimate on.

Supported formats:
  ✓ Number
  ✓ String

Words Per Minute

💾 Average reading speed in words per minute (default: 350).

Supported formats:
  ✓ Number
  ✓ String

Minimum Seconds

💾 Minimum number of seconds to return (default: 30).

Supported formats:
  ✓ Number
  ✓ String

Input Setup

Input Function (optional)

⚙️ Optional pre-processing function applied to the input before internal logic (e.g., convert object to string, normalize case). Internal transformations such as case handling will still apply afterward.

Result Handling

Output Function (optional)

⚙️ Optional function to apply to the result before returning it (e.g., str => str + ' €', val => val !== undefined for boolean conversion). Useful for chaining transformations on the output.

Word Count number

💡 Type any text to see the result update live

🎯 Using special value — click input to type instead

Test with:

Falsy undefined null "" empty 0 false NaN

Truthy true 42 "hello" {} empty [] empty {a:1} [1,2,3]

Words Per Minute number

Minimum Seconds number

🔗 Result Handling — Chain Variables

Chain apply-mode variables to the output. Each variable receives the result of the previous one.

estimateReadingTime()

+ Chain another variable

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Related Variables

Same category: GTM

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Under the Hood

📜 View Implementation Code

/**
* Estimates reading time in seconds based on word count.
* 
* @param {number} data.src - The total number of words to base the estimate on.
* @param {number|string} data.wpm - Average reading speed in words per minute (default: 350).
* @param {number|string} data.min - Minimum number of seconds to return (default: 30).
* @param {Function|string} [data.out] - Optional output handler: function to transform result or string with format.
*
* Direct-mode specific parameters:
* @param {Function} [data.pre] - Optional pre-processor function to transform src before calculation.
* 
* @returns {number|undefined} Estimated reading time in seconds, or undefined if word count is invalid.
* @author Markus Baersch
* @see https://bit.ly/4katPuD
* @modified Adaptation to the library framework
*
* @framework ggLowCodeGTMKit
*/
const Math = require('Math');
const makeNumber = require('makeNumber');

const estimateReadingTime = function(wordCount, wordsPerMinute, minSecs) {
   const words = makeNumber(wordCount);
   if (words !== words) { return undefined; }
   const wpmNum = makeNumber(wordsPerMinute);
   const wpm = (wpmNum === wpmNum && wordsPerMinute !== undefined) ? wpmNum : 350;
   const minSecsNum = makeNumber(minSecs);
   const minSeconds = (minSecsNum === minSecsNum && minSecs !== undefined) ? minSecsNum : 30;
   const timeInSeconds = Math.round((words / wpm) * 60);
   return Math.max(timeInSeconds, minSeconds);
};

const safeFunction = fn => typeof fn === 'function' ? fn : x => x;
const out = safeFunction(data.out);
// ===============================================================================
// estimateReadingTime - Direct mode
// ===============================================================================
const applyCast = (castFn, value) => safeFunction(castFn)(value);
const value = applyCast(data.pre, data.src);
return out(estimateReadingTime(value, data.wpm, data.min));
// ===============================================================================
// estimateReadingTime(...) – Apply Mode
// ===============================================================================
/*
return function(value, wordsPerMinute, minSecs) {
   return out(estimateReadingTime(value, data.wpm , data.min));
};
*/

🧪 View Test Scenarios (5 tests)

✅ '[example] Default reading time'
✅ Valid word count with custom words per minute - calculates correctly
✅ Low word count below minimum - returns minimum seconds
✅ Valid word count with custom minimum - respects custom minimum
✅ '[example] Invalid input returns undefined'