Why Doesn't the CSS Calc() Function Work For Me

CSS calc() not working

To quote MDN

The + and - operators must always be surrounded by whitespace. The
operand of calc(50% -8px) for instance will be parsed as a percentage
followed by a negative length, an invalid expression, while the
operand of calc(50% - 8px) is a percentage followed by a minus sign
and a length. The * and / operators do not require whitespace, but
adding it for consistency is allowed, and recommended.

Space your stuff out, and it will probably work.

Why the CSS calc() function is not working?

You need to add spaces between operators, it's a common mistake to forget them. We can also nest operation using calc as many as we want but they are equivalent to simple parentheses.

From the documentation:

Note: The + and - operators must be surrounded by whitespace. For
instance, calc(50% -8px) will be parsed as a percentage followed by a
negative length—an invalid expression—while calc(50% - 8px) is a
percentage followed by a subtraction operator and a length. Likewise,
calc(8px + -50%) is treated as a length followed by an addition
operator and a negative percentage.
The * and / operators do not require whitespace, but adding it for
consistency is both allowed and recommended.
Note: It is permitted to nest calc() functions, in which case the
inner ones are treated as simple parentheses.

.one {
  background: red;
  width: calc(100% - 150px);
  margin-top: calc(20px + calc(40px * 2)); /*Same as calc(20px + (40px * 2))*/
  height: calc(100px - 10px);
  padding: calc(5% + 10px) calc(5% - 5px);
}

<div class="one">

</div>

Why is CSS calc(100%-250px) not working?

It's because you have to put a space between the + or - operator in order for it to work properly.

div {  background-color: blue;  height: 50px;  width: calc(100% - 250px);}

<div></div>

CSS calc() function doesn't seem to work correctly

You need spaces in your calc() declaration:

calc(50vw - 150px) not calc(50vw-150px)

EG:

@media (max-width: 999px) {  #containerProgressbarPageLoad {    background:red;    position: relative;    margin-left: calc(50vw - 150px);    margin-right: calc(50vw - 150px);  }}

<div id="containerProgressbarPageLoad">containerProgressbarPageLoad</div>

Why doesn't css-calc() work when using 0 inside the equation?

The first equation is invalid because it will lead to calc(-10px + 0)

Note: Because <number-token>s are always interpreted as <number>s or <integer>s, "unitless 0" <length>s aren’t supported in calc(). That is, width: calc(0 + 5px); is invalid, even though both width: 0; and width: 5px; are valid. ^ref

And if the result was non-zero you will fall into this:

At + or -, check that both sides have the same type, or that one side is a <number> and the other is an <integer>. If both sides are the same type, resolve to that type. If one side is a <number> and the other is an <integer>, resolve to <number>.

The last one is more logical since 10px + 5 has no meaning whearas we may think that 10px + 0 is simply 10px but for the browser it's not.

Related question: Why doesn't min() (or max()) work with unitless 0?

CSS3 calc() function not working correctly

You need to know that between inline and inline-block elements, the spaces matters. So if you have a whitespace between two inline elements, it takes account in the total calculation. To avoid this there are a lot of tricks, but the simplest is the following:

 .containero {
       font-size: 0;
 }

Add this property in your CSS and it works. Working example:

.containero {    font-size: 0;    width: 100%;    background-color: yellow;    display: inline-block;    box-sizing:border-box;}
.noey, .yeso {  border: 1px solid red;  width: 30px;  height: 30px;  text-align: center;  vertical-align: middle;   display:inline-block;  color: red;  padding:0px;  box-sizing:border-box;
}

.inpoot {  height: 31px;  margin: 0 5px;  display:inline-block;  width: calc(100% - 70px);  box-sizing:border-box;}

<div class="containero">  <button class="noey">No</button>  <input  class="inpoot" />  <button class="yeso">Yes</button></div>

CSS calc function does not center

You can use margin:auto; for adding space from both side. And you need to set it 100% - 28px

.container-card {    background-color: grey;    height: 500px;     }   .container-holder {      background-color: gold;      width: calc(100% - 28px);      height: 300px;      margin: auto;    }

<div class="container-card">    <div class="container-holder">
    </div>  </div>

CSS calc() function

You cannot divide by units, only by numbers.

CSS3 calc(100%-88px) not working in Chrome

The problem in the question was caused by the lack of space around the subtraction operator.

Note that the grammar requires spaces around binary ‘+’ and ‘-’
operators. The ‘*’ and ‘/’ operators do not require spaces.

https://www.w3.org/TR/css3-values/#calc-syntax

^{This article mentions that the spacing is necessary for unambiguous parsing.}

Bad: calc(100%-88px)

Good: calc(100% - 88px)

How do I know it is not recognizing it? Because of the strikethrough
and the yellow triangle icon next to the style rule in chrome dev
tools.

A property that is ~~struck~~ through when viewed in Chrome's developer tools may be valid but overridden; however, a property struck through and with a warning triangle icon next to it is invalid.

2022 Update - calc() is supported by all modern browsers in a wide variety of scenarios, though proper spacing is still required.