What is initial scale, user-scalable, minimum-scale, maximum-scale attribute in meta tag?

Solution 1:

They are viewport meta tags, and is most applicable on mobile browsers.

width=device-width

This means, we are telling to the browser “my website adapts to your device width”.

initial-scale

This defines the scale of the website, This parameter sets the initial zoom level, which means 1 CSS pixel is equal to 1 viewport pixel. This parameter help when you're changing orientation, or preventing default zooming. Without this parameter, responsive site won't work.

maximum-scale

Maximum-scale defines the maximum zoom. When you access the website, top priority is maximum-scale=1, and it won’t allow the user to zoom.

minimum-scale

Minimum-scale defines the minimum zoom. This works the same as above, but it defines the minimum scale. This is useful, when maximum-scale is large, and you want to set minimum-scale.

user-scalable

User-scalable assigned to 1.0 means the website is allowing the user to zoom in or zoom out.

But if you assign it to user-scalable=no, it means the website is not allowing the user to zoom in or zoom out.

Solution 2:

user-scalable:

user-scalable=yes (default) to allow the user to zoom in or out on the web page;

user-scalable=no to prevent the user from zooming in or out.

You can get more detailed information by reading the following articles.

http://www.html-5.com/metatags/meta-viewport.html
https://css-tricks.com/snippets/html/responsive-meta-tag/
https://developer.mozilla.org/en-US/docs/Web/HTML/Element/meta#Attributes

Demo Code (recommended)

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0, minimum-scale=0.5, maximum-scale=3.0">
</head>
<body>
    <header>
    </header>
    <main>
        <section>
            <h1>do not using <mark>user-scalable=no</mark></h1>
        </section>
    </main>
    <footer>
    </footer>
</body>
</html>

Solution 3:

viewport meta tag on mobile browser,

The initial-scale property controls the zoom level when the page is first loaded. The maximum-scale, minimum-scale, and user-scalable properties control how users are allowed to zoom the page in or out.

Solution 4:

This meta tag is used by all responsive web pages, that is those that are designed to layout well across device types - phone, tablet, and desktop. The attributes do what they say. However, as MDN's Using the viewport meta tag to control layout on mobile browsers indicates,

On high dpi screens, pages with initial-scale=1 will effectively be zoomed by browsers.

I've found that the following ensures that the page displays with zero zoom by default.

<meta name="viewport" content="width=device-width, initial-scale=0.86, maximum-scale=3.0, minimum-scale=0.86">