New CSS units that account for mobile viewports with dynamic toolbars.


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<br />

> [!TIP]
> **Celebration:** This web feature is now available in all three browser engines!

## The viewport and its units

To size something as tall as the viewport, you can use the `vw` and `vh` units.

- `vw` = 1% of the width of the viewport size.
- `vh` = 1% of the height of the viewport size.

Give an element a width of `100vw` and a height of `100vh`, and it will cover the viewport entirely.
![A light blue element set to be 100vw by 100vh, covering the entire viewport. The viewport itself is indicated using a blue dashed border.](https://web.dev/static/blog/viewport-units/image/a-light-blue-element-set-6daa79ea2e48a.png) A light blue element set to be 100vw by 100vh, covering the entire viewport.  
The viewport itself is indicated using a blue dashed border.

The `vw` and `vh` units landed in browsers with these additional units

- `vi` = 1% of the size of the viewport's inline axis.
- `vb` = 1% of the size of the viewport's block axis.
- `vmin` = the smaller of `vw` or `vh`.
- `vmax` = the larger of `vw` or `vh`.

These units have good browser support.


Browser Support

- ![Chrome: 20.](data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='24' height='24' viewBox='-10 -10 276 276'%3E%3ClinearGradient id='a' x1='145' x2='34' y1='253' y2='61' gradientUnits='userSpaceOnUse'%3E%3Cstop offset='0' stop-color='%231e8e3e'/%3E%3Cstop offset='1' stop-color='%2334a853'/%3E%3C/linearGradient%3E%3ClinearGradient id='b' x1='111' x2='222' y1='254' y2='62' gradientUnits='userSpaceOnUse'%3E%3Cstop offset='0' stop-color='%23fcc934'/%3E%3Cstop offset='1' stop-color='%23fbbc04'/%3E%3C/linearGradient%3E%3ClinearGradient id='c' x1='17' x2='239' y1='80' y2='80' gradientUnits='userSpaceOnUse'%3E%3Cstop offset='0' stop-color='%23d93025'/%3E%3Cstop offset='1' stop-color='%23ea4335'/%3E%3C/linearGradient%3E%3Ccircle cx='128' cy='128' r='64' fill='%23fff'/%3E%3Cpath fill='url(%23a)' d='M96 183a64 64 0 0 1-23-23L17 64a128 128 0 0 0 111 192l55-96a64 64 0 0 1-87 23Z'/%3E%3Cpath fill='url(%23b)' d='M192 128a64 64 0 0 1-9 32l-55 96A128 128 0 0 0 239 64H128a64 64 0 0 1 64 64Z'/%3E%3Ccircle cx='128' cy='128' r='52' fill='%231a73e8'/%3E%3Cpath fill='url(%23c)' d='M96 73a64 64 0 0 1 32-9h111a128 128 0 0 0-222 0l56 96a64 64 0 0 1 23-87Z'/%3E%3C/svg%3E)
- ![Edge: 12.](data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' xmlns:xlink='http://www.w3.org/1999/xlink' width='24' height='24' viewBox='0 0 27600 27600'%3E%3ClinearGradient id='A' gradientUnits='userSpaceOnUse'/%3E%3ClinearGradient id='B' x1='6870' x2='24704' y1='18705' y2='18705' xlink:href='%23A'%3E%3Cstop offset='0' stop-color='%230c59a4'/%3E%3Cstop offset='1' stop-color='%23114a8b'/%3E%3C/linearGradient%3E%3ClinearGradient id='C' x1='16272' x2='5133' y1='10968' y2='23102' xlink:href='%23A'%3E%3Cstop offset='0' stop-color='%231b9de2'/%3E%3Cstop offset='.16' stop-color='%231595df'/%3E%3Cstop offset='.67' stop-color='%230680d7'/%3E%3Cstop offset='1' stop-color='%230078d4'/%3E%3C/linearGradient%3E%3CradialGradient id='D' cx='16720' cy='18747' r='9538' xlink:href='%23A'%3E%3Cstop offset='.72' stop-opacity='0'/%3E%3Cstop offset='.95' stop-opacity='.53'/%3E%3Cstop offset='1'/%3E%3C/radialGradient%3E%3CradialGradient id='E' cx='7130' cy='19866' r='14324' gradientTransform='matrix(.14843 -.98892 .79688 .1196 -8759 25542)' xlink:href='%23A'%3E%3Cstop offset='.76' stop-opacity='0'/%3E%3Cstop offset='.95' stop-opacity='.5'/%3E%3Cstop offset='1'/%3E%3C/radialGradient%3E%3CradialGradient id='F' cx='2523' cy='4680' r='20243' gradientTransform='matrix(-.03715 .99931 -2.12836 -.07913 13579 3530)' xlink:href='%23A'%3E%3Cstop offset='0' stop-color='%2335c1f1'/%3E%3Cstop offset='.11' stop-color='%2334c1ed'/%3E%3Cstop offset='.23' stop-color='%232fc2df'/%3E%3Cstop offset='.31' stop-color='%232bc3d2'/%3E%3Cstop offset='.67' stop-color='%2336c752'/%3E%3C/radialGradient%3E%3CradialGradient id='G' cx='24247' cy='7758' r='9734' gradientTransform='matrix(.28109 .95968 -.78353 .22949 24510 -16292)' xlink:href='%23A'%3E%3Cstop offset='0' stop-color='%2366eb6e'/%3E%3Cstop offset='1' stop-color='%2366eb6e' stop-opacity='0'/%3E%3C/radialGradient%3E%3Cpath id='H' d='M24105 20053a9345 9345 0 01-1053 472 10202 10202 0 01-3590 646c-4732 0-8855-3255-8855-7432 0-1175 680-2193 1643-2729-4280 180-5380 4640-5380 7253 0 7387 6810 8137 8276 8137 791 0 1984-230 2704-456l130-44a12834 12834 0 006660-5282c220-350-168-757-535-565z'/%3E%3Cpath id='I' d='M11571 25141a7913 7913 0 01-2273-2137 8145 8145 0 01-1514-4740 8093 8093 0 013093-6395 8082 8082 0 011373-859c312-148 846-414 1554-404a3236 3236 0 012569 1297 3184 3184 0 01636 1866c0-21 2446-7960-8005-7960-4390 0-8004 4166-8004 7820 0 2319 538 4170 1212 5604a12833 12833 0 007684 6757 12795 12795 0 003908 610c1414 0 2774-233 4045-656a7575 7575 0 01-6278-803z'/%3E%3Cpath id='J' d='M16231 15886c-80 105-330 250-330 566 0 260 170 512 472 723 1438 1003 4149 868 4156 868a5954 5954 0 003027-839 6147 6147 0 001133-850 6180 6180 0 001910-4437c26-2242-796-3732-1133-4392-2120-4141-6694-6525-11668-6525-7011 0-12703 5635-12798 12620 47-3654 3679-6605 7996-6605 350 0 2346 34 4200 1007 1634 858 2490 1894 3086 2921 618 1067 728 2415 728 2952s-271 1333-780 1990z'/%3E%3Cuse fill='url(%23B)' xlink:href='%23H'/%3E%3Cuse fill='url(%23D)' opacity='.35' xlink:href='%23H'/%3E%3Cuse fill='url(%23C)' xlink:href='%23I'/%3E%3Cuse fill='url(%23E)' opacity='.4' xlink:href='%23I'/%3E%3Cuse fill='url(%23F)' xlink:href='%23J'/%3E%3Cuse fill='url(%23G)' xlink:href='%23J'/%3E%3C/svg%3E)
- ![Firefox: 19.](data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='24' height='24' viewBox='0 0 512 512'%3E%3Cdefs%3E%3CradialGradient id='ff-b' cx='428.5' cy='55.1' r='501' gradientUnits='userSpaceOnUse'%3E%3Cstop offset='.1' stop-color='%23ffbd4f'/%3E%3Cstop offset='.2' stop-color='%23ffac31'/%3E%3Cstop offset='.3' stop-color='%23ff9d17'/%3E%3Cstop offset='.3' stop-color='%23ff980e'/%3E%3Cstop offset='.4' stop-color='%23ff563b'/%3E%3Cstop offset='.5' stop-color='%23ff3750'/%3E%3Cstop offset='.7' stop-color='%23f5156c'/%3E%3Cstop offset='.8' stop-color='%23eb0878'/%3E%3Cstop offset='.9' stop-color='%23e50080'/%3E%3C/radialGradient%3E%3CradialGradient id='ff-c' cx='245.4' cy='259.9' r='501' gradientUnits='userSpaceOnUse'%3E%3Cstop offset='.3' stop-color='%23960e18'/%3E%3Cstop offset='.3' stop-color='%23b11927' stop-opacity='.7'/%3E%3Cstop offset='.4' stop-color='%23db293d' stop-opacity='.3'/%3E%3Cstop offset='.5' stop-color='%23f5334b' stop-opacity='.1'/%3E%3Cstop 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- ![Safari: 6.](data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' xmlns:xlink='http://www.w3.org/1999/xlink' width='24' height='24' viewBox='195 190 135 135'%3E%3Cdefs%3E%3ClinearGradient id='s-a' x1='132.6' x2='134.4' y1='111.7' y2='-105.3' xlink:href='%23s-b'%3E%3Cstop offset='0' stop-color='%23d2d2d2' /%3E%3Cstop offset='.5' stop-color='%23f2f2f2' /%3E%3Cstop offset='1' stop-color='%23fff' /%3E%3C/linearGradient%3E%3ClinearGradient id='s-b' gradientUnits='userSpaceOnUse' /%3E%3ClinearGradient id='s-c' x1='65.4' x2='67.4' y1='115.7' y2='17.1' xlink:href='%23s-b'%3E%3Cstop offset='0' stop-color='%23005ad5' /%3E%3Cstop offset='.2' stop-color='%230875f0' /%3E%3Cstop offset='.3' stop-color='%23218cee' /%3E%3Cstop offset='.6' stop-color='%2327a5f3' /%3E%3Cstop offset='.8' stop-color='%2325aaf2' /%3E%3Cstop offset='1' stop-color='%2321aaef' /%3E%3C/linearGradient%3E%3ClinearGradient id='s-d' x1='158.7' x2='176.3' y1='96.7' y2='79.5' xlink:href='%23s-b'%3E%3Cstop offset='0' stop-color='%23c72e24' /%3E%3Cstop offset='1' stop-color='%23fd3b2f' /%3E%3C/linearGradient%3E%3CradialGradient id='s-i' cx='-69.9' cy='69.3' r='54' gradientTransform='matrix(.9 -.01 .04 2.72 -9 -120)' xlink:href='%23s-b'%3E%3Cstop offset='0' stop-color='%2324a5f3' stop-opacity='0' /%3E%3Cstop offset='1' stop-color='%231e8ceb' /%3E%3C/radialGradient%3E%3CradialGradient id='s-j' cx='109.3' cy='13.8' r='93.1' gradientTransform='matrix(-.02 1.1 -1.04 -.02 137 -115)' xlink:href='%23s-b'%3E%3Cstop offset='0' stop-opacity='0' /%3E%3Cstop offset='1' stop-color='%235488d6' stop-opacity='0' /%3E%3Cstop offset='1' stop-color='%235d96eb' /%3E%3C/radialGradient%3E%3C/defs%3E%3Crect width='220' height='220' x='22' y='-107' fill='url(%23s-a)' ry='49' transform='matrix(.57 0 0 .57 187 256)' /%3E%3Cg transform='translate(194 190)'%3E%3Ccircle cx='67.8' cy='67.7' fill='url(%23s-c)' paint-order='stroke fill markers' r='54' /%3E%3Ccircle cx='-69.9' cy='69.3' fill='url(%23s-i)' transform='translate(138 -2)' r='54' /%3E%3C/g%3E%3Cellipse cx='120' cy='14.2' fill='url(%23s-j)' rx='93.1' ry='93.7' transform='matrix(.58 0 0 .58 192 250)' /%3E%3Cg transform='matrix(.58 0 0 .57 197 182)'%3E%3Cpath fill='%23cac7c8' d='M46 192h1l72-48-7-9-66 57Z' /%3E%3Cpath fill='%23fbfffc' d='M46 191v1l66-57-7-9-59 65Z' /%3E%3Cpath fill='url(%23s-d)' d='m119 144-7-9 66-57-59 66Z' /%3E%3Cpath fill='%23fb645c' d='m105 126 7 9 66-57-1-1-72 49Z' /%3E%3C/g%3E%3Cpath stroke='%23fff' stroke-linecap='round' stroke-miterlimit='1' stroke-width='1.3' d='m287 278 3-2m-12-17 8-2m-8-3h4m-4-13 8 2m-8 3h4m-1-13 7 3m-4-11 7 4m-2-11 6 6m0-12 6 7m1-11 4 6m4-10 3 7m5-9 2 7m15-7-1 7m10-5-3 7m11-4-4 7m11-2-5 6m16 7-7 4m10 4-7 3m10 6-8 1m8 16-8-2m5 10-7-3m4 11-7-4m2 11-6-5m0 11-5-6m-2 11-4-7m-4 11-3-8m-6 10-1-8m-16 8 2-8m-10 5 3-7m-11 4 4-7m-11 2 5-6m-8 3 3-3m4 8 2-3m5 8 2-4m6 7 1-4m8 5v-4m8 4v-4m9 3-1-4m9 1-2-4m9 0-2-4m9-2-3-3m8-4-3-2m8-5-4-2m7-6-4-1m5-8h-4m4-8h-4m3-9-4 1m1-9-4 2m-1-9-3 2m-2-9-3 3m-4-8-2 3m-5-8-2 4m-6-6-1 3m-8-5v4m-8-4v4m-9-2 1 3m-9 0 2 3m-9 1 2 3m-9 2 3 3m-8 4 3 2m-8 5 4 2m-7 6 4 1m-4 25 4-1m-2 5 7-3m-6 7 4-2m-2 6 7-4m-13-21h8m41-41v-8m0 99v-8m49-42h-8' transform='translate(-65 8)' /%3E%3C/svg%3E)

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## The need for new viewport units

While the existing units work well on desktop, it's a different story on mobile devices. There, the viewport size is influenced by the presence or absence of dynamic toolbars. These are user interfaces such as address bars and tab bars.

Although the viewport size can change, the `vw` and `vh` sizes do not. As a result, elements sized to be `100vh` tall will bleed out of the viewport.
![100vh on mobile is too tall on load.](https://web.dev/static/blog/viewport-units/image/100vh-mobile-is-too-tall-d4220eaf6b22c.png) 100vh on mobile is too tall on load.

When scrolling down these dynamic toolbars will retract. In this state, elements sized to be `100vh` tall will cover the entire viewport.
![100vh on mobile is “correct” when the User-Agent user interfaces are retracted.](https://web.dev/static/blog/viewport-units/image/100vh-mobile-is-correct-7866c8c47b9ed.png) 100vh on mobile is "correct" when the User-Agent user interfaces are retracted.

To solve this problem, the various states of the viewport have been specified at the CSS Working Group.

- **Large viewport**: The viewport sized assuming any UA interfaces that are dynamically expanded and retracted to be retracted.
- **Small Viewport**: The viewport sized assuming any UA interfaces that are dynamically expanded and retracted to be expanded.

![Visualizations of the large and small viewports.](https://web.dev/static/blog/viewport-units/image/visualizations-the-large-1fd4fa842e688.png) Visualizations of the large and small viewports.

The new viewports also have units assigned to them:

- Units representing the large viewport have the `lv` prefix. The units are `lvw`, `lvh`, `lvi`, `lvb`, `lvmin`, and `lvmax`.
- Units representing the small viewport have the `sv` prefix. The units are `svw`, `svh`, `svi`, `svb`, `svmin`, and `svmax`.

The sizes of these viewport-percentage units are fixed (and therefore stable) unless the viewport itself is resized.
![Two mobile browser visualizations positioned next to each other. One has an element sized to be 100svh and the other 100lvh.](https://web.dev/static/blog/viewport-units/image/two-mobile-browser-visual-ca2bb505efaf1.png) Two mobile browser visualizations positioned next to each other.  
One has an element sized to be 100svh and the other 100lvh.

In addition to the large and small viewports, there's also a dynamic viewport which has dynamic consideration of the UA UI:

- When the dynamic toolbars are expanded, the dynamic viewport is equal to the size of the small viewport.
- When the dynamic toolbars are retracted, the dynamic viewport is equal to the size of the large viewport.

Its accompanied units have the `dv` prefix: `dvw`, `dvh`, `dvi`, `dvb`, `dvmin`, and `dvmax`. Their sizes are clamped between their `lv*` and `sv*` counterparts.
![100dvh adapts itself to be either the large or small viewport size.](https://web.dev/static/blog/viewport-units/image/100dvh-adapts-itself-be-91c728b09836d.png) 100dvh adapts itself to be either the large or small viewport size.

These units ship in Chrome 108, joining Safari and Firefox which already have support.


Browser Support

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- ![Safari: 15.4.](data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' xmlns:xlink='http://www.w3.org/1999/xlink' width='24' height='24' viewBox='195 190 135 135'%3E%3Cdefs%3E%3ClinearGradient id='s-a' x1='132.6' x2='134.4' y1='111.7' y2='-105.3' xlink:href='%23s-b'%3E%3Cstop offset='0' stop-color='%23d2d2d2' /%3E%3Cstop offset='.5' stop-color='%23f2f2f2' /%3E%3Cstop offset='1' stop-color='%23fff' /%3E%3C/linearGradient%3E%3ClinearGradient id='s-b' gradientUnits='userSpaceOnUse' /%3E%3ClinearGradient id='s-c' x1='65.4' x2='67.4' y1='115.7' y2='17.1' xlink:href='%23s-b'%3E%3Cstop offset='0' stop-color='%23005ad5' /%3E%3Cstop offset='.2' stop-color='%230875f0' /%3E%3Cstop offset='.3' stop-color='%23218cee' /%3E%3Cstop offset='.6' stop-color='%2327a5f3' /%3E%3Cstop offset='.8' stop-color='%2325aaf2' /%3E%3Cstop offset='1' stop-color='%2321aaef' /%3E%3C/linearGradient%3E%3ClinearGradient id='s-d' x1='158.7' x2='176.3' y1='96.7' y2='79.5' xlink:href='%23s-b'%3E%3Cstop offset='0' stop-color='%23c72e24' /%3E%3Cstop offset='1' stop-color='%23fd3b2f' /%3E%3C/linearGradient%3E%3CradialGradient id='s-i' cx='-69.9' cy='69.3' r='54' gradientTransform='matrix(.9 -.01 .04 2.72 -9 -120)' xlink:href='%23s-b'%3E%3Cstop offset='0' stop-color='%2324a5f3' stop-opacity='0' /%3E%3Cstop offset='1' stop-color='%231e8ceb' /%3E%3C/radialGradient%3E%3CradialGradient id='s-j' cx='109.3' cy='13.8' r='93.1' gradientTransform='matrix(-.02 1.1 -1.04 -.02 137 -115)' xlink:href='%23s-b'%3E%3Cstop offset='0' stop-opacity='0' /%3E%3Cstop offset='1' stop-color='%235488d6' stop-opacity='0' /%3E%3Cstop offset='1' stop-color='%235d96eb' /%3E%3C/radialGradient%3E%3C/defs%3E%3Crect width='220' height='220' x='22' y='-107' fill='url(%23s-a)' ry='49' transform='matrix(.57 0 0 .57 187 256)' /%3E%3Cg transform='translate(194 190)'%3E%3Ccircle cx='67.8' cy='67.7' fill='url(%23s-c)' paint-order='stroke fill markers' r='54' /%3E%3Ccircle cx='-69.9' cy='69.3' fill='url(%23s-i)' transform='translate(138 -2)' r='54' /%3E%3C/g%3E%3Cellipse cx='120' cy='14.2' fill='url(%23s-j)' rx='93.1' ry='93.7' transform='matrix(.58 0 0 .58 192 250)' /%3E%3Cg transform='matrix(.58 0 0 .57 197 182)'%3E%3Cpath fill='%23cac7c8' d='M46 192h1l72-48-7-9-66 57Z' /%3E%3Cpath fill='%23fbfffc' d='M46 191v1l66-57-7-9-59 65Z' /%3E%3Cpath fill='url(%23s-d)' d='m119 144-7-9 66-57-59 66Z' /%3E%3Cpath fill='%23fb645c' d='m105 126 7 9 66-57-1-1-72 49Z' /%3E%3C/g%3E%3Cpath stroke='%23fff' stroke-linecap='round' stroke-miterlimit='1' stroke-width='1.3' d='m287 278 3-2m-12-17 8-2m-8-3h4m-4-13 8 2m-8 3h4m-1-13 7 3m-4-11 7 4m-2-11 6 6m0-12 6 7m1-11 4 6m4-10 3 7m5-9 2 7m15-7-1 7m10-5-3 7m11-4-4 7m11-2-5 6m16 7-7 4m10 4-7 3m10 6-8 1m8 16-8-2m5 10-7-3m4 11-7-4m2 11-6-5m0 11-5-6m-2 11-4-7m-4 11-3-8m-6 10-1-8m-16 8 2-8m-10 5 3-7m-11 4 4-7m-11 2 5-6m-8 3 3-3m4 8 2-3m5 8 2-4m6 7 1-4m8 5v-4m8 4v-4m9 3-1-4m9 1-2-4m9 0-2-4m9-2-3-3m8-4-3-2m8-5-4-2m7-6-4-1m5-8h-4m4-8h-4m3-9-4 1m1-9-4 2m-1-9-3 2m-2-9-3 3m-4-8-2 3m-5-8-2 4m-6-6-1 3m-8-5v4m-8-4v4m-9-2 1 3m-9 0 2 3m-9 1 2 3m-9 2 3 3m-8 4 3 2m-8 5 4 2m-7 6 4 1m-4 25 4-1m-2 5 7-3m-6 7 4-2m-2 6 7-4m-13-21h8m41-41v-8m0 99v-8m49-42h-8' transform='translate(-65 8)' /%3E%3C/svg%3E)

<br />

> [!NOTE]
> **Note:** In browsers that don't have dynamic UA UI--such as Chrome on desktop--the size of the large, small, and dynamic viewports are the same.

## Caveats

There's a few caveats to know about Viewport Units:

- None of the viewport units take the size of scrollbars into account. On systems that have classic scrollbars enabled, an element sized to `100vw` will therefore be a little bit too wide. This is as [per specification](https://www.w3.org/TR/css-values-4/#viewport-relative-lengths:%7E:text=In%20all%20cases%2C%20scrollbars%20are%20assumed%20not%20to%20exist.).

- The values for the dynamic viewport do not update at 60fps. In all browsers updating is throttled as the UA UI expands or retracts. Some browsers even debounce updating entirely depending on the gesture (a slow scroll versus a swipe) used.

- The on-screen keyboard (also known as the virtual keyboard) is not considered part of the UA UI. Therefore it does not affect the size of the viewport units. In Chrome [you can opt-in to a behavior where the presence of the virtual keyboard does affect the viewport units](https://developer.chrome.com/blog/viewport-resize-behavior#opting-in-to-a-different-behavior).

## Additional resources

To learn more about viewports and these units check out [this episode of HTTP 203](https://www.youtube.com/watch?v=xl9R8aTOW_I). In it, [Bramus](https://web.dev/authors/bramus) tells [Jake](https://web.dev/authors/jakearchibald) all about the various viewports and explains how exactly the sizes of these units are determined.

[Video](https://www.youtube.com/watch?v=xl9R8aTOW_I)

Additional reading material:

- [CSS Values 4 Specification: Viewport-relative lengths](https://www.w3.org/TR/css-values-4/#viewport-relative-lengths)
- [ChromeStatus Entry](https://chromestatus.com/feature/5170718078140416?context=myfeatures)
- [Layout Viewport explainer](https://github.com/web-platform-tests/interop-2022-viewport/blob/main/explainers/layout-viewport.md)
- [Viewport Units explainer](https://github.com/web-platform-tests/interop-2022-viewport/blob/main/explainers/viewport-units.md)