Web typography is one of the most important elements in a page's design , and understanding how units of measurement work is key to achieving a responsive and adaptable design. One of the most common transformations web developers perform is converting from pixels to em. In this article, we'll explore the formula for this conversion and how to implement it using an HTML form and JavaScript.
What Are Pixels and EM?
Pixels are a fixed unit of measurement used in web design, while ems are a relative measurement based on the font size of the parent element. This means that an em can change size if the font settings are changed, making them ideal for responsive design.
Formula to Convert Pixels to EM
The formula for converting pixels to em is quite simple:
em = pixels / base font size
Typically the base font size is 16 pixels, although this can vary in different projects.
Practical Example
Suppose we want to convert 32 pixels to em. The conversion would be:
em = 32 / 16 = 2em This is a very useful technique to achieve a flexible layout.
Implementation
Enter the pixels to get the value in em:
HTML and Javascript Form Sample Code
<div class="mb-4">
<form id="conversionForm" onsubmit="return convertPixelsToEm()">
<div class="btn-group mb-3" role="group" aria-label="Basic example">
<input type="number" class="form-control" id="pixels" value="16" required="">
<input type="submit" class="btn btn-primary" value="Convertir">
</div>
<div id="result" class="fw-bold"></div>
</form>
</div>
<script>
function convertPixelsToEm() {
var pixels = document.getElementById('pixels').value;
var baseSize = 16;
var em = pixels / baseSize;
document.getElementById('result').innerHTML = pixels + ' píxeles son ' + em + ' em';
return false; // Evitar el envío del formulario
}
</script>
Converting units is essential to maintaining the structure and presentation of a website, especially on mobile devices. By using em instead of pixels, you make your design more flexible and adaptable to different screen sizes. Remember that understanding how to apply these formulas and techniques will allow you to build a more accessible and visually appealing website.
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