Edit in JSFiddle

h1
{
    font-size: 10pt;
}
h2
{
    font-size: 20px;
}
h3
{
    font-size: xx-large;
}
h4
{
    font-size: 250%;
}

<h1>This text size is 10 points</h1>
<h2>This text size is 20 pixels</h2>
<h3>This text size is Extra Large</h3>
<h4>This text size is 250 percent large</h4>