<link rel="stylesheet" href="/css/style.css" type="text/css">
<link rel="stylesheet" href="/css/print.css" type="text/css" media="print">

在你的normal style.css中:

table.tableclassname {
  width: 400px;
}

在你的print.css中:

table.tableclassname {
  width: 16 cm;
}

我使用HTML生成报告，在真实的纸张上正确地打印出真实大小。

如果你小心地使用mm作为CSS文件中的单位，你应该是OK的，至少对于单页。不过，人们可以通过改变浏览器中的打印缩放来搞砸你。

我似乎记得我所做的每一件事都是单页的，所以我不必担心分页——那可能要困难得多。

A4尺寸为210x297mm

所以你可以用CSS设置HTML页面来适应这些大小:

html,body{
    height:297mm;
    width:210mm;
}

我在谷歌上搜索“A4 CSS页面模板”(codepend .io)后看到了这个解决方案。它使用<page>标记在浏览器中显示A4 (A3,A5，也是纵向)大小的区域。在这个标记中显示内容，但绝对位置仍然相对于浏览器区域。

身体{ 背景:rgb (204204204); ｝ 页面{ 背景:白色; 显示:块; 保证金:0自动; margin-bottom: 0.5厘米; 箱影:0 0 0.5cm rgba(0,0,0,0.5); ｝ 页面(=“A4大小){ 宽度:21厘米; 高度:29.7厘米; ｝ 布局页面(大小= " A4 "][=“肖像”]{ 宽度:29.7厘米; 高度:21厘米; ｝ @media print { 正文，页{ 保证金:0; 不必:0; ｝ ｝ <页面大小= >“A4 A4页面< / > <page size="A4" layout="portrait">A4 portrait</page>

这适用于我没有任何其他css/js库包括在内。适用于当前的浏览器(IE, FF, Chrome)。

PPI and DPI make absolutely no difference to how a document will print off a browser. the printer takes no information on screen dot pitch or the DPI of the images etc. if you are printing images they would print at a size similar in proportion to how they are displayed on screen. the print processor of the browser would increase the DPI of the images from something rather low like 72dpi to whatever DPI the rest of the document is. say the image displays as half a page wide, then its about 4" wide physically. the pixel width of the image would be approx 300px to display correctly in the browser. by the time it prints at a nominal 300DPI, the processor has added pixels and the image will grow to around 1200px which at 300 DPI is 4".

当涉及到矢量或非基于像素的元素，如文本，打印机从驱动程序中选择自己的DPI，这与屏幕点间距或浏览器宽度无关。如果浏览器宽度为3000px，打印处理器将适当地换行文本。

heres what makes it hard about creating print displays: each browser and printer will interpret text sizes (pt, em, px) and spacing in its own way. depending on what printer, browser and maybe even OS you use, you will get a different amount of lines and characters per page. so even if you test on your computer using your browser and printer and figure out that you can display the text in a box at 640x900px and its perfect on print, the next guy who tries to print will possibly get it printing differently. there really is no way to force each printer and browser to get it identical each time.

忘记像素，更忘记DPI，你唯一可以使用像素的事情是设置一个表宽度，模拟打印机上可打印区域的宽度。在这种情况下，我发现640px宽是接近的。

寻找类似的问题，我发现这个- http://www.indigorose.com/forums/archive/index.php/t-13334.html

A4是一种文档格式，作为屏幕图像，这取决于图像的分辨率，例如A4文档调整为:

72 dpi (web) = 595 X 842像素 300 dpi(打印)= 2480 X 3508像素 (这是我所知道的“A4”。210mm X 297mm @ 300 dpi) 600 dpi (打印)= 4960 X 7016像素