CSS units Cheat Sheet
Long gone are the days when we used to use only ‘px’ (pixels) in our CSS. Today there are a lot of options to choose from. What unit you choose depends on the context, some should be used for text, some for containers, some for print.
| Unit | Name | Equivalent to | Relative to |
|---|---|---|---|
| cm | centimeters | 1cm = 37.8px = 25.2/64in | Absolute (Used for print) |
| mm | millimeters | 1mm = 1/10th of 1cm | Absolute (Used for print) |
| Q | quarter-millimeters | 1Q = 1/40th of 1cm | Absolute (Used for print in Japan) |
| in | inches | 1in = 2.54cm = 96px | Absolute (Used for print) |
| pc | picas | 1pc = 1/6th of 1in | Absolute (Used for print) |
| pt | points | 1pt = 1/72th of 1in | Absolute (Used for print) |
| px | pixels | 1px = 1/96th of 1in | Absolute |
| em | parent font size | 1em = parent font size | Font |
| rem | font size of the root element | 1rem = size of root element | Font |
| ex | height of letter ‘x’ | 1ex = height of the glyph ‘x’ | Font |
| rex | height of root letter ‘x’ | 1rex = height of the root element glyph ‘x’ | Font |
| ch | width of number 0 | 1ch = width of glyph ‘0’ | Font |
| rch | width of root number 0 | 1ch = width of root element glyph ‘0’ | Font |
| ic | width of gliph 水 | 1ic = witht of glyph ‘水’ | Font |
| ric | width of root gliph 水 | 1ic = witht of root element glyph ‘水’ | Font |
| cap | height of capital letters | 1cap = height of a capital letter | Font |
| rcap | height of root capital letters | 1cap = height of a root element capital letter | Font |
| lh | line height of the element | 1lh = height of the text line | Font |
| rlh | line height of the root element | 1rlh = height of the root text line | Font |
| vw | default viewport width | 1vw = 1% of the default viewport’s width. | Viewport |
| vh | default viewport height | 1vh = 1% of the default viewport’s height. | Viewport |
| vi | default viewport inline size | 1vi = 1% of the size of the viewport in the inline direction | Viewport |
| vb | default viewport box size | 1vb = 1% of the size of the viewport in the block direction. | Viewport |
| vmin | default viewport minimum dimension | 1vmin = 1% of the default viewport’s smaller dimension. | Viewport |
| vmax | default viewport maximum dimension | 1vmax = 1% of the default viewport’s larger dimension. | Viewport |
| lvw | large viewport width | 1lvw = 1% of the large viewport’s width. | Viewport |
| lvh | large viewport height | 1lvh = 1% of the large viewport’s height. | Viewport |
| lvmin | large viewport minimum dimension | 1lvmin = 1% of the large viewport’s smaller dimension. | Viewport |
| lvmax | large viewport maximum dimension | 1lvmax = 1% of the large viewport’s larger dimension. | Viewport |
| svw | small viewport width | 1svw = 1% of the small viewport’s width. | Viewport |
| svh | small viewport height | 1svh = 1% of the small viewport’s height. | Viewport |
| svmin | small viewport minimum dimension | 1svmin = 1% of the small viewport’s smaller dimension. | Viewport |
| svmax | small viewport maximum dimension | 1svmax = 1% of the small viewport’s larger dimension. | Viewport |
| dvw | dynamic viewport width | 1dvw = 1% of the dynamic viewport’s width. | Viewport |
| dvh | dynamic viewport height | 1dvh = 1% of the dynamic viewport’s height. | Viewport |
| dvmin | dynamic viewport minimum dimension | 1dvmin = 1% of the dynamic viewport’s smaller dimension. | Viewport |
| dvmax | dynamic viewport maximum dimension | 1dvmax = 1% of the dynamic viewport’s larger dimension. | Viewport |
| deg | degrees | 1deg = 1/360 of a full circle | Circle |
| grad | gradians | 1grad = 1/400 of a full circle | Circle |
| rad | radians | 1rad = 1/2π of a full circle | Circle |
| turn | turn | 1turn = a full circle | Circle |
| s | second | 1s = 1/60 of a minute duration | Time |
| ms | millisecond | 1ms = 1/1000 of a second duration | Time |
| Hz | Hertz | 1Hz = one occurrence per second | N/a |
| kHz | killoHertz | 1kHz = 1000Hz | N/a |
| dpi | dots per inch | 1dpi = one dot per inch | Resolution |
| dpcm | dots per centimeter | 1dpcm = one dot per centimeter | Resolution |
| dppx | dots per pixel | 1dpcm = one dot per pixel | Resolution |
| fr | flex fraction | 1fr = a fraction of available free space | Grid layout only |
Soon there will also be container relative units:
| Unit | Name | Equivalent to | Relative to |
|---|---|---|---|
| cqw | container width | 1% of a query container’s width | Container |
| cqh | container height | 1% of a query container’s height | Container |
| cqi | container inline size | 1% of a query container’s inline size | Container |
| cqb | container block size | 1% of a query container’s block size | Container |
| cqmin | container minimum size | The smaller value of cqi or cqb | Container |
| cqmax | container maximum size | The larger value of cqi or cqb | Container |
Using multiple units together with CSS functions
CSS has some very useful functions that can determine values by using a single unit or multiple units. Here are some examples:
calc
You can use calc() function to determine a dimension using multiple units:
width: calc(100% - 16px);
The width is calculated dynamically by subtracting 16px from the maximum width.
clamp
clamp() function accepts a minimum, an ideal and a maximum value. All those units can be different if necessary:
font-size: clamp(18px, 4vw, 3rem);
The font size will be a minimum of 18px, a maximum of 3rem and 4vw in the rest.
min and max
min() and max() are two functions that can limit a value depending on context:
width: min(100vw - 3rem, 80ch);
Here the width will be the minimum between 100vw - 3rem and 80ch. On different screen sizes, there will be a different minimum.
minmax
There is also minmax() function that defines a range of values:
width: minmax(30ch, 80ch)
In this case the width will have a minium value of 30ch, a maximum of 80ch and any value between.