What is aspect ratio?

Aspect ratio is the proportional relationship between width and height (W:H). Common ratios: 16:9 (HD and UHD television), 4:3 (standard-definition television), 1:1 (square), 9:16 (vertical video such as reels) and 21:9 (ultrawide). To find the aspect ratio of an image or screen from its size, enter the width and height in Size → Ratio: 1600 × 900 and 4032 × 2268 are both 16:9, and 3000 × 2000 is 3:2. Batch mode does the same for a list of sizes.

How do I calculate new dimensions while keeping aspect ratio?

If you know the ratio and one dimension, use cross-multiplication: new height = (new width × ratio_height) / ratio_width. Example: scaling a 1920×1080 (16:9) image to 1280 wide: height = (1280 × 9) / 16 = 720. This calculator handles all conversions instantly.

What pixel dimensions are 16:9?

The common ones are 1280×720, 1920×1080, 2560×1440 and 3840×2160: 720p through 4K, all exactly 16:9. For anything outside that list, set the ratio to 16:9 and type your width into Ratio → Size; the height follows. Watch for the near-misses. 1366×768 is the classic one: exact 16:9 at 1366 wide works out to 768.375, so the panel is a fraction wider than 16:9 and the calculator simplifies it to 683:384 rather than 16:9. The Sizes tab in the Help panel lists more of them.

Is 16x9 the same as 16:9?

Yes. 16x9, 16 x 9, 16/9, 16 by 9, 16 to 9, 16-9 and 16:9 all describe the same shape (16 units of width for every 9 of height), and none of them is a different ratio. The colon is the conventional way to write it; the "x" form usually turns up when someone is thinking in pixel dimensions like 1920x1080. Only the notation changes, never the arithmetic. In Ratio → Size mode the two numbers go in separate fields, so the separator never comes up at all. In Batch mode it does: paste one set of dimensions per line using x, × or : between the numbers, and each line is reduced to its lowest terms. The same goes for 9x16, 9:16 and 9/16, the vertical shape: tap 9:16 in Ratio → Size and type 1080 as the width to get 1920.

What is a safe area and how much margin should I leave?

The safe area is the part of the frame left after a margin you choose is taken off every edge. Set the margin and the calculator reports that region: a 10% margin on a 1920×1080 frame leaves 1536×864. No one margin fits every platform. Pinterest, for one, lists unequal safe zones for a Pin, so a platform's own figures, where it gives them, are the ones to use.

What aspect ratio is best for YouTube?

The standard aspect ratio for YouTube on a computer is 16:9, with 1920×1080 and 3840×2160 among the resolutions YouTube lists for it. The player adapts to a video with another shape, and YouTube asks you not to add black bars to the file. A Short must be square or vertical and up to three minutes long.

How many pixels do I need for a print size and DPI?

Pixels = Physical Size (inches) × DPI, so DPI = Pixels ÷ Physical Size: a 3000×2000 pixel image printed at 10×6.67 inches is 300 DPI. DPI / Print mode works in the first direction: enter your print width, height and DPI (or pick a paper size) to get the whole-pixel dimensions you need before ordering a print. To check an existing image, divide its pixel width by the print width.

How do I crop a photo to a specific aspect ratio?

Use Ratio → Size mode to work out the crop dimensions: enter the target ratio (e.g. 16:9) and one side of your desired crop; the other side is calculated for you. You then crop your image in your photo editor to those exact dimensions, centered on the part of the photo you want to keep.

How do I compare different aspect ratios before choosing one?

Use Compare mode: enter a shared base width and select the ratios you want to compare (e.g. 16:9, 4:3, 21:9). The calculator shows the resulting height and a visual box for each ratio side by side, so you can see how much taller or shorter each format is at the same width.

What aspect ratio should I use for LinkedIn, TikTok, Pinterest, or Facebook?

LinkedIn gives 1.91:1 (1200 × 627) for an image on a Page post with a link, 1584 × 396 (4:1) for a profile cover and 1512 × 256 for a Page cover. Pinterest's ad specification recommends 2:3 (1000 × 1500), and TikTok's recommends 9:16 for in-feed video ads. Facebook says a Page cover shows at 16:9 on a computer and 2.4:1 on a phone. Pick a Platform Preset in Ratio → Size or Size → Ratio to fill these in.

What's the difference between aspect ratio and resolution?

Aspect ratio is the proportional relationship (e.g., 16:9), while resolution is the actual pixel dimensions (e.g., 1920×1080). Multiple resolutions can share the same aspect ratio: 1920×1080, 1280×720, and 3840×2160 all have a 16:9 aspect ratio.

Aspect Ratio Calculator - 16:9, Print & Platform Presets

Formulas and sources

Each formula this calculator uses, where it comes from, and what it leaves out. "How it works" shows the same formula with your own numbers.

Ratio from width and height

Size → Ratio, DPI / Print and Batch modes

Ratio = W : H (simplified by GCD)

Ratio: the simplified ratio
W: width
H: height
GCD: the greatest common divisor of W and H, found by Euclid's algorithm

Both sides are divided by their greatest common divisor, so 1920 × 1080 becomes 16:9. A size close to a standard shape but not on it does not reduce to it: 1366 × 768 is 683:384. In DPI / Print the ratio comes from the print size (millimeters for ISO paper), not the rounded pixels.

Source: Standard formula; no single publisher. HD and UHD picture sizes reduce to the 16:9 their standards give: 1920 × 1080 in ITU-R BT.709-6 [1], and 3840 × 2160 and 7680 × 4320 in BT.2020-2 [2].

Height from a ratio

Ratio → Size mode, with the width typed

Height = Width × H ÷ W

W:H is the ratio. The side you did not type is worked out to two decimals: 16:9 at 1366 wide is 768.38 high.

Source: Standard formula; no single publisher.

Width from a ratio

Ratio → Size mode, with the height typed

Width = Height × W ÷ H

W:H is the ratio: 4:3 at 1080 high is 1440 wide.

Source: Standard formula; no single publisher.

Heights at one width

Compare mode

Height = Base Width × (Ratio Height ÷ Ratio Width)

Height: the height for one compared ratio
Base Width: the width every compared ratio shares
(Ratio Height ÷ Ratio Width): the ratio as height over width: 9 ÷ 16 for 16:9

A blank or zero base width is 1,920.

Source: Standard formula; no single publisher.

Pixels for a print size

DPI / Print mode

Pixels = Inches × DPI

Pixels: the width or height in pixels
Inches: the print width or height
DPI: pixels per inch; a blank field is 300

Each side is rounded to a whole pixel. An ISO paper size is taken in millimeters and divided by 25.4 first, so A4 at 300 DPI is 2480 × 3508. DPI here means pixels per inch, not a printer's dots.

Source: Standard formula; no single publisher. An inch is exactly 25.4 millimeters, NIST SP 811 [3].

Safe area

Ratio → Size, Size → Ratio and DPI / Print modes

Safe width = Width × (1 - 2 × Margin ÷ 100) Safe height = Height × (1 - 2 × Margin ÷ 100)

Width: the frame width
Height: the frame height
Margin: the percentage you choose, taken off every edge, at most 45%

A 10% margin keeps 1536 × 864 of a 1920 × 1080 frame. Platforms crop unequal parts. Pinterest lists Pin safe zones of 270 pixels at the top and 790 at the bottom, and X says 60 pixels at the top and bottom of a header may be cropped.

Source: CalcTrail's own measure; no publisher. It is one equal margin, not a platform's own safe zone (Pinterest [4], X [5]).

Platform presets

Ratio → Size and Size → Ratio modes

YouTube Video (16:9): 1920 × 1080
Instagram Feed (1:1): 1080 × 1080, inside the 1.91:1 to 3:4 Instagram keeps at full resolution
Instagram Story/Reel (9:16): 1080 × 1920, the narrowest shape a reel may be
TikTok Video (9:16): 9:16 from an ad specification (at least 540 × 960); the preset fills 1080 × 1920
LinkedIn Link Post (1.91:1): 400:209, 1200 × 627
LinkedIn Cover Photo (4:1): 1584 × 396, a profile cover; a Page cover is 1512 × 256
X Header (3:1): 1500 × 500
Facebook Page cover file (851 × 315): 851 × 315, shown at 16:9 on a computer and 2.4:1 on a phone
Pinterest Pin (2:3): 1000 × 1500, from an ad specification
Ultrawide (21:9): 2520 × 1080, which is 7:3
Presentation Slide (16:10): 1920 × 1200
A4 Print, 300 DPI (2480 × 3508): 620:877, as DPI / Print gives A4
US Letter Print (8.5:11): 17:22, 2550 × 3300

Platform figures as of October 2026; platforms change them. Each preset fills the ratio and a target width in Ratio → Size, and the width and height in Size → Ratio.

Source: Each platform's own help page: YouTube [6], Instagram [7] [8], LinkedIn [9] [10], X [5] and Facebook [11]. TikTok's 9:16 [12] and Pinterest's 2:3 [13] are their ad specifications, and 16:10 is a Google Slides page size [14]. No standard sets 21:9: CTA-861-G specifies 64:27 and notes that it is near 21:9 [15].

Compared ratios

Compare mode

16:9 is the picture shape of HD and UHD television, and 4:3 of standard-definition television. 21:9, 1:1, 9:16, 3:2, 5:4 and 2:1 are shapes, not standard formats.

Source: 16:9 from ITU-R BT.709-6 [1] and BT.2020-2 [2]; 4:3 from BT.601-7 [16]. No standard sets 21:9 [15]. No primary source found for 3:2 as 35 mm film or 5:4 as a print format.

Paper sizes

DPI / Print mode

US Letter: 8.5 × 11 in
US Legal: 8.5 × 14 in
Tabloid: 11 × 17 in
A3: 297 × 420 mm
A4: 210 × 297 mm
A5: 148 × 210 mm
Photo: 4 × 6, 5 × 7 and 8 × 10 in

ISO sizes are worked in millimeters, so A4 is 70:99 and 2480 × 3508 pixels at 300 DPI.

Source: A4 and US Letter as 37 CFR 1.52 gives them [17]; US Legal as 12 CFR 1010.102 gives it, "approximately" [18]. A3 and A5 belong to the A series of ISO 216 [19]; no free primary source states their sizes. Tabloid and the photo sizes: no primary source found.

Sources

International Telecommunication Union (ITU-R). Recommendation ITU-R BT.709-6, Parameter values for the HDTV standards for production and international programme exchange, section 2, Picture characteristics, items 2.1 to 2.5. June 2015.
International Telecommunication Union (ITU-R). Recommendation ITU-R BT.2020-2, Parameter values for ultra-high definition television systems for production and international programme exchange, Table 1, Picture spatial characteristics. October 2015.
National Institute of Standards and Technology. NIST Guide to the SI, Appendix B.9: Factors for units listed by kind of quantity or field of science, length, the inch. Special Publication 811.
Pinterest Help. Review Pin specs, safe zones. Undated page, read October 5, 2026.
X Help Center. Help with uploading a profile photo, header images. Undated page, read October 5, 2026.
Google, YouTube Help. Video resolution & aspect ratios. Undated page, read October 5, 2026.
Instagram Help Center. Image resolution of photos you share on Instagram. Undated page, read October 5, 2026.
Instagram Help Center. Reel size and aspect ratios on Instagram. Undated page, read October 5, 2026.
LinkedIn Help. Image specifications for your LinkedIn Pages and Career Pages, Custom image specifications, and Page cover image. Undated page, read October 5, 2026.
LinkedIn Help. Add or change the cover image on your profile. Undated page, read October 5, 2026.
Facebook Help Center. Facebook Page profile picture and cover photo dimensions. Undated page, read October 5, 2026.
TikTok, TikTok Ads Manager Help Center. TikTok Auction In-Feed Ads, video ad specifications. Last updated March 2026, read in the Internet Archive's capture of April 20, 2026.
Pinterest Business Help. Review ad specs. Undated page, read October 5, 2026.
Google, Google Docs Editors Help. Change slide size & measurement units in Google Slides. Undated page, read October 5, 2026.
Consumer Technology Association (CTA). CTA-861-G, A DTV Profile for Uncompressed High Speed Digital Interfaces, definition of Picture Aspect Ratio, and Table 3, note 6. November 2016.
International Telecommunication Union (ITU-R). Recommendation ITU-R BT.601-7, Studio encoding parameters of digital television for standard 4:3 and wide-screen 16:9 aspect ratios. March 2011.
US Patent and Trademark Office, Code of Federal Regulations. 37 CFR 1.52, Language, paper, writing, margins, read-only optical disc specifications, paragraph (a)(1)(ii). eCFR, current as of October 1, 2026.
Consumer Financial Protection Bureau, Code of Federal Regulations. 12 CFR 1010.102, General instructions for completing the Statement of Record, paragraph (a). eCFR, current as of October 1, 2026.
International Organization for Standardization (ISO). ISO 216:2007, Writing paper and certain classes of printed matter, Trimmed sizes, A and B series, and indication of machine direction. Edition 2, September 2007; under systematic review as of October 2026.

What this calculator does not cover

Presets are the ratios and sizes platforms give on their own help pages as of October 2026, and platforms change them.
The safe area is one equal margin on every edge, not a platform's own safe zone.
It works out sizes and ratios; it does not crop or resample an image.
DPI here is pixels per inch, the screen term, not the dots per inch of a printer.

Sources checked on October 5, 2026.

Help

Select mode: Ratio → Size, Size → Ratio, DPI / Print, Batch, or Compare.
Enter values: Add width and height or ratio values based on the selected mode. In Ratio → Size, the Common ratios buttons set 16:9, 4:3, 21:9, 1:1, 9:16 or 3:2 in one tap.
Apply a Platform Preset (optional): Fill the ratio and a target width (Ratio → Size) or a width and height (Size → Ratio) from a platform, print or presentation format.
Review output: See the normalized ratio and computed dimensions, or side-by-side comparisons in Compare mode.
Swap or export: In Size → Ratio, swap width and height for portrait versus landscape, or export your result as JSON, CSV or PDF.

Understanding Aspect Ratios

Print aspect ratio: matching pixels to physical size

The same pixels cover a larger print at a lower density: a 3000×2000 pixel image covers 10 × 6.67 in at 300 pixels per inch, or 20 × 13.3 in at 150. Use DPI / Print mode to convert a target print size and DPI into the pixel dimensions and ratio you need before you export. Pick a paper size such as A4, US Letter or a 4 × 6 photo to fill the print size.

Common 16:9 pixel dimensions

1280×720 (720p), 1920×1080 (1080p), 2560×1440 (1440p) and 3840×2160 (4K UHD) are each exactly 16:9. That is why they scale between one another cleanly: divide any of them by 16 and by 9 and you get the same multiplier for both. Enter any width in Ratio → Size with the ratio set to 16:9 and the matching height appears, which is the quick way to check an unusual width. It also catches the near-misses: 1366×768, the old laptop resolution, looks like 16:9 and is not: exact 16:9 at 1366 wide would be 768.375, so it simplifies to 683:384 instead of 16:9. Tap 16:9 under Common ratios in Ratio → Size, then type a width. The Sizes tab in this Help panel lists more exact 16:9 sizes, and common sizes that only look like 16:9, with the ratio the calculator gives for each.

Common 4:3 sizes, and fitting 4:3 into 16:9

The common 4:3 sizes are 640×480 (VGA), 800×600, 1024×768, 1400×1050, 1600×1200 and 2048×1536. Moving 4:3 material into a 16:9 frame, or the other way round, comes down to one choice. Keep the height and the picture is narrower than the frame: 4:3 at 1080 high is 1440 wide, which leaves a 240-pixel bar on each side of a 1920×1080 frame. Keep the width and you crop instead: 16:9 at 1024 wide is 576 high, so 192 rows of a 1024×768 picture are cut. Ratio → Size gives the matching side for either ratio from whichever side you type, and Compare mode shows 4:3 and 16:9 side by side at the same width.

Safe area: the part that survives cropping

A frame that is the right ratio can still lose the thing that mattered. A platform can crop a frame for thumbnails and previews, and an app's controls can cover the edges of a vertical video. The safe-area figure takes a margin you choose off every edge of the frame and reports the region inside it. At 10% a 1920×1080 frame keeps 80% of each side, 1536×864, and at 20% only 1152×648. Faces, text and logos inside that box are less likely to be lost to cropping, though each platform crops and covers its own parts of a frame.

Matching a platform format

Platform Preset fills in the ratio of a platform format, an ultrawide frame, a presentation slide or a print size such as A4 or US Letter. The platform figures come from each platform's own help page as of October 2026, and platforms change them. A preset fills the ratio and a target width in Ratio → Size, or a width and height in Size → Ratio. DPI / Print mode has a Paper Size list instead, which fills the print width and height.

Comparing ratios before you commit

Widescreen (16:9), standard (4:3), ultrawide (21:9), and square (1:1) all crop differently at the same width. Compare mode lines several ratios up side by side at a shared base width so you can see the height difference before choosing a format for video, print, or a responsive layout.

How aspect ratio relates to the general Ratio Calculator

Aspect ratio is a width:height ratio, so at its core it is the same math as the general Ratio Calculator. This tool adds what image and video work needs: DPI-to-pixel conversion, platform presets, and side-by-side ratio comparison. Use this calculator for anything involving pixels, screens, print, or platform formats. Use the Ratio Calculator for ratios that are not about dimensions, and the DTI Calculator for the debt-to-income ratio specifically.

Common 16:9 sizes

A size is exactly 16:9 when its width divides by 16 and its height by 9 with the same answer: 1920 ÷ 16 = 120 and 1080 ÷ 9 = 120.

Exact 16:9 sizes
Name	Width × height	Megapixels
360p	640 × 360	0.23
qHD	960 × 540	0.52
720p (HD)	1280 × 720	0.92
HD+	1600 × 900	1.44
1080p (Full HD)	1920 × 1080	2.07
1440p (QHD)	2560 × 1440	3.69
QHD+	3200 × 1800	5.76
4K UHD (2160p)	3840 × 2160	8.29
5K	5120 × 2880	14.75
8K UHD (4320p)	7680 × 4320	33.18

Turn any of them on its side for 9:16, the vertical shape: 720 × 1280, 1080 × 1920, 1440 × 2560 or 2160 × 3840.

Close to 16:9, but not

Sizes close to 16:9 that are not 16:9
Width × height	Simplest ratio	Where it is seen
1366 × 768	683:384	An older laptop screen
854 × 480	427:240	YouTube's 480p; exact 16:9 is 480.375 high
1920 × 1200	8:5	A 16:10 monitor
2560 × 1080	64:27	Ultrawide, sold as 21:9
3440 × 1440	43:18	Ultrawide, sold as 21:9
4096 × 2160	256:135	Cinema 4K (DCI)

To check a size of your own, enter it in Size → Ratio. To get the height for a width, set 16:9 in Ratio → Size and type the width.

Aspect Ratio Calculator - 16:9, Print & Platform Presets

Formulas and sources

Ratio from width and height

Height from a ratio

Width from a ratio

Heights at one width

Pixels for a print size

Safe area

Platform presets

Compared ratios

Paper sizes

Sources

What this calculator does not cover

Help

Understanding Aspect Ratios

Print aspect ratio: matching pixels to physical size

Common 16:9 pixel dimensions

Common 4:3 sizes, and fitting 4:3 into 16:9

Safe area: the part that survives cropping

Matching a platform format

Comparing ratios before you commit

How aspect ratio relates to the general Ratio Calculator

Common 16:9 sizes

Close to 16:9, but not

Frequently Asked Questions

Related Calculators

Ratio Calculator

Color Converter

Unit Converter

Aspect Ratio Calculator - 16:9, Print & Platform Presets

Formulas and sources

Ratio from width and height

Height from a ratio

Width from a ratio

Heights at one width

Pixels for a print size

Safe area

Platform presets

Compared ratios

Paper sizes

Sources

What this calculator does not cover

Help

Quick Start Guide

Understanding Aspect Ratios

Print aspect ratio: matching pixels to physical size

Common 16:9 pixel dimensions

Common 4:3 sizes, and fitting 4:3 into 16:9

Safe area: the part that survives cropping

Matching a platform format

Comparing ratios before you commit

How aspect ratio relates to the general Ratio Calculator

Features

Common Use Cases

Common 16:9 sizes

Close to 16:9, but not

Frequently Asked Questions

Related Calculators

Ratio Calculator

Color Converter

Unit Converter