[html] How to make an element width: 100% minus padding?

I have an html input.

The input has padding: 5px 10px; I want it to be 100% of the parent div's width(which is fluid).

However using width: 100%; causes the input to be 100% + 20px how can I get around this?

Example

Just understand the difference between width:auto; and width:100%; Width:auto; will (AUTO)MATICALLY calculate the width in order to fit the exact given with of the wrapping div including the padding. Width 100% expands the width and adds the padding.

Use css calc()

Super simple and awesome.

input {
    width: -moz-calc(100% - 15px);
    width: -webkit-calc(100% - 15px);
    width: calc(100% - 15px);
}?

As seen here: Div width 100% minus fixed amount of pixels
By webvitaly (https://stackoverflow.com/users/713523/webvitaly)
Original source: http://web-profile.com.ua/css/dev/css-width-100prc-minus-100px/

Just copied this over here, because I almost missed it in the other thread.

Here is the recommendation from codeontrack.com, which has good solution examples:

Instead of setting the width of the div to 100%, set it to auto, and be sure, that the <div> is set to display: block (default for <div>).

Assuming i'm in a container with 15px padding, this is what i always use for the inner part:

width:auto;
right:15px;
left:15px;

That will stretch the inner part to whatever width it should be less the 15px either side.

Try this:

width: 100%;
box-sizing: border-box;

You can do it without using box-sizing and not clear solutions like width~=99%.

Demo on jsFiddle:

• Keep input's padding and border
• Add to input negative horizontal margin = border-width + horizontal padding
• Add to input's wrapper horizontal padding equal to margin from previous step

HTML markup:

<div class="input_wrap">
    <input type="text" />
</div>

CSS:

div {
    padding: 6px 10px; /* equal to negative input's margin for mimic normal `div` box-sizing */
}

input {
    width: 100%; /* force to expand to container's width */ 
    padding: 5px 10px;
    border: none;
    margin: 0 -10px; /* negative margin = border-width + horizontal padding */ 
}

For me, using margin:15px;padding:10px 0 15px 23px;width:100%, the result was this:

The solution for me was to use width:auto instead of width:100%. My new code was:

margin:15px;padding:10px 0 15px 23px;width:auto. Then the element aligned properly:

Use padding in percentages too and remove from the width:

padding: 5%;
width: 90%;

What about wrapping it in a container. Container shoud have style like:

{
    width:100%;
    border: 10px solid transparent;
}

You can do this:

width: auto;
padding: 20px;

Move the input box' padding to a wrapper element.

<style>
div.outer{ background: red; padding: 10px; }
div.inner { border: 1px solid #888; padding: 5px 10px; background: white; }
input { width: 100%; border: none }
</style>

<div class="outer">
    <div class="inner">
       <input/>
    </div>
</div>

See example here: http://jsfiddle.net/L7wYD/1/

You can try some positioning tricks. You can put the input in a div with position: relative and a fixed height, then on the input have position: absolute; left: 0; right: 0;, and any padding you like.

Live example

This is why we have box-sizing in CSS.

I’ve edited your example, and now it works in Safari, Chrome, Firefox, and Opera. Check it out: http://jsfiddle.net/mathias/Bupr3/ All I added was this:

input {
  -webkit-box-sizing: border-box;
     -moz-box-sizing: border-box;
          box-sizing: border-box;
}

Unfortunately older browsers such as IE7 do not support this. If you’re looking for a solution that works in old IEs, check out the other answers.