1080 1350 Ratio: What 1080x1350 Means and Why Instagram Uses It

A 1080 x 1350 pixel image has an aspect ratio of 4:5, which is a decimal ratio of 0.800 — the tallest portrait size Instagram displays in the feed without cropping. You get 4:5 by dividing both numbers by their greatest common divisor of 270: 1080 ÷ 270 = 4 and 1350 ÷ 270 = 5. Drop any width and height into our Aspect Ratio Calculator to confirm the simplified ratio and decimal in one click.

A common point of confusion is people typing "1080 1350" and expecting it to mean some exotic ratio. It does not. It is plain 4:5 — the same 4:5 you would write for an 8x10 photo print scaled up. The mistake to watch for: if you resize a 1080x1350 graphic to 1080x1080 for a square post, you lose 270 pixels of height, which can clip the bottom line of text off a quote graphic. The ratio changes from 0.800 to 1.000, and the crop is unavoidable.

This guide explains exactly what the 1080 1350 ratio is, how to verify it by hand, why Instagram standardized on it, and how to resize to or from it without distortion. For broader platform sizing, see our companion data piece on home AV and screen-size calculator usage.

What the 1080 1350 Ratio Actually Is

The 1080 1350 ratio is a pixel dimension, not a ratio name. The width is 1080 pixels and the height is 1350 pixels. Because the height is larger than the width, the image is in portrait (vertical) orientation.

To turn raw pixels into a clean ratio, you simplify the fraction 1080/1350 the same way you simplify any fraction: divide both sides by the largest number that goes into both evenly. That number is the greatest common divisor (GCD).

Here is the GCD found with the Euclidean algorithm, one step at a time:

• 1350 ÷ 1080 = 1, remainder 270
• 1080 ÷ 270 = 4, remainder 0
• The last nonzero remainder is 270, so GCD(1080, 1350) = 270

Now divide both dimensions by 270:

• 1080 ÷ 270 = 4
• 1350 ÷ 270 = 5

So 1080 x 1350 simplifies to 4:5. As a decimal, 4 ÷ 5 = 0.800. You can reproduce every step of this in the Aspect Ratio Calculator, or check the underlying fraction math in our Ratio Calculator.

The 1080 1350 Ratio in Numbers

Every value in this table is derived from the two dimensions 1080 and 1350. Megapixels are width × height ÷ 1,000,000.

The inverse decimal of 1.250 is worth remembering: a 4:5 portrait image is 25% taller than it is wide. That extra height is the entire reason the format exists, as the next section explains.

Why Instagram Uses the 1080 1350 Ratio (4:5)

Instagram recommends 1080 x 1350 pixels (4:5) for feed posts and carousels because it is the tallest image the feed accepts, and taller images take up more screen as people scroll. Per Buffer's Instagram image size guide, 1080 x 1350 pixels (4:5) is the recommended portrait size for feed posts, and it is the tallest of the supported feed formats.

A 4:5 portrait at 1080x1350 gives you 1350 pixels of height. A 1:1 square at 1080x1080 gives you only 1080. That is 270 extra pixels, or 25% more vertical screen coverage, for free — the same width, just taller. SocialBee's 2026 aspect ratio guide notes that this added height is why 4:5 has replaced the old 1:1 square as the default recommendation: more screen time per post tends to help engagement.

There is one catch introduced in the 2025 grid redesign. The profile grid now previews posts in a 3:4 shape, not 4:5, even though uploads are still capped at 4:5. According to SocialPilot's Instagram image size guide, the feed restricts in-feed content to a maximum 1080 wide × 1350 tall (4:5), while the profile grid now previews posts in a taller 3:4 shape. SocialPilot lists that grid preview as roughly 1015 × 1350; a mathematically exact 3:4 crop of a 1350-pixel-tall image is 1012.5 pixels wide, so the safe-zone numbers below use 1012.

Every decimal above is the width divided by the height. The portrait row at 0.800 is the 1080 1350 ratio, and it is the one to design for if you want a single asset that fills the feed and survives the grid crop.

How to Resize To or From the 1080 1350 Ratio

The rule for resizing without distortion is simple: keep the ratio constant. If you change the width, change the height by the same factor — never stretch one dimension alone.

The formulas are:

• New Height = New Width × (Original Height ÷ Original Width)
• New Width = New Height × (Original Width ÷ Original Height)

For a 4:5 image, the height is always 1.25 times the width, and the width is always 0.8 times the height.

Worked Example 1: Scaling 1080x1350 Up to a 4K-Tall Asset

Say you want a higher-resolution 4:5 graphic that is 1600 pixels wide. Keep the 0.800 ratio:

• New Height = 1600 × (1350 ÷ 1080) = 1600 × 1.25 = 2000
• Result: 1600 × 2000, still 4:5 (GCD is 400; 1600 ÷ 400 = 4, 2000 ÷ 400 = 5)

The decimal is 1600 ÷ 2000 = 0.800, identical to the original. No cropping, no stretching.

Worked Example 2: Shrinking 1080x1350 for a Thumbnail

You need a small 4:5 thumbnail 320 pixels wide:

• New Height = 320 × 1.25 = 400
• Result: 320 × 400 (GCD is 80; 320 ÷ 80 = 4, 400 ÷ 80 = 5)

Again the ratio holds at 0.800. Run either of these through the Aspect Ratio Calculator and it returns the matching dimension instantly.

Worked Example 3: Converting a Square 1080x1080 to 1080x1350

This is the conversion that trips people up. You cannot reach the full 1080x1350 size from a 1080x1080 square without losing something — either you add new image area or you give up pixels. Your two honest options are:

1. Add canvas (keep all 1080px of width): Place the 1080x1080 image on a 1080x1350 background, leaving 270 pixels of color or pattern (135 top and bottom if centered). Nothing is cropped, and the result is a true 1080x1350.
2. Crop the width down to 4:5: A square can be cropped to a 4:5 shape — you just trim the width, not the height. Crop 1080 × 1080 to 864 × 1080 (864 ÷ 1080 = 0.800 = 4:5), losing 216 pixels of width (108 each side). That gives you a genuine 4:5 image, but at 864 × 1080 it is smaller than 1080x1350, so you would scale it up to 1080 × 1350 afterward. The takeaway: cropping a square to 4:5 is possible by removing width; what is impossible is gaining the extra height of a full 1080x1350 without adding canvas.

The 1080 1350 Ratio vs Other Common Sizes

Designers constantly switch between 4:5, 1:1, and 9:16. Here is how the 1080 1350 ratio compares to the formats it shares a width with. Megapixels are width × height ÷ 1,000,000.

The 1080x1350 portrait carries 1.46 MP — 25% more pixels than the 1.17 MP square at the same width, matching its 25% greater height. Notice that 9:16 (Reels) is even taller at 0.563 decimal, so a 4:5 feed graphic will not fill a Reel without adding top-and-bottom space. To compare pixel density across these sizes on an actual screen, run them through the DPI / PPI Calculator, and to translate any image into physical print inches use the Unit Converter.

How to Verify Any Pixel Size Yourself

You do not need software to confirm a ratio. Follow these four steps for any width and height:

1. Find the GCD. Divide the larger number by the smaller, keep the remainder, then divide the previous divisor by that remainder. Repeat until the remainder is 0. The last divisor is the GCD. For 1080 and 1350, that is 270.
2. Divide both dimensions by the GCD. 1080 ÷ 270 = 4 and 1350 ÷ 270 = 5, giving 4:5.
3. Get the decimal. Divide width by height: 1080 ÷ 1350 = 0.800. Below 1 means portrait.
4. Count megapixels. Multiply width × height, then divide by 1,000,000: 1080 × 1350 = 1,458,000 = 1.46 MP.

The Aspect Ratio Calculator automates all four steps and also solves the reverse problem — give it a target width and it returns the height that holds your ratio.

Frequently Asked Questions

What is the 1080 1350 ratio?

The 1080 1350 ratio is the 4:5 aspect ratio, because 1080 and 1350 both divide by their greatest common divisor of 270 to give 4 and 5; as a decimal it is 0.800, and the image is in portrait (vertical) orientation.

What aspect ratio is 1080 x 1350 pixels?

1080 x 1350 pixels is a 4:5 aspect ratio with a decimal value of 0.800, the tallest portrait size Instagram allows for feed posts and carousels at 1080 pixels of width.

Why does Instagram recommend 1080 x 1350?

Instagram recommends 1080 x 1350 (4:5) because it is the maximum allowed feed height, giving 25% more vertical screen coverage than a 1080x1080 square at the same width, which tends to increase the time a post stays on screen.

How many megapixels is a 1080 x 1350 image?

A 1080 x 1350 image contains 1,458,000 pixels, which is 1.46 megapixels (1080 × 1350 ÷ 1,000,000), about 25% more pixels than a 1080x1080 square.

How do I resize an image to 1080 x 1350 without cropping?

To reach 1080 x 1350 from another 4:5 image, scale both dimensions by the same factor so the 0.800 ratio holds; to convert a square or wider image, add canvas (extra background) rather than stretching, because adding height to a square without new content is impossible without distortion.

Is 1080 x 1350 the same as 4:5 and 8:10?

Yes — 1080 x 1350 simplifies to 4:5, and 8:10 also simplifies to 4:5 (both divide by 2), so a 4:5 social image shares the exact proportions of a classic 8x10 photo print.

Will a 1080 x 1350 post get cropped in the Instagram grid?

The full 1080 x 1350 image shows in the feed, but the profile grid previews it as roughly 3:4, trimming about 34 pixels off each side, so keep important elements inside a centered safe zone of about 1012 pixels wide.

Related Articles

• TV Mounting Height, Screen Size, and Home AV Setup Data in 2026 — Session data on how people size and place screens, where aspect ratio drives the layout math.
• Optimal Viewing Distance for a 4K TV: 2026 Size-by-Size Guide — How aspect ratio and width set the right distance for any display.

Related Calculators

• Aspect Ratio Calculator — Simplify any width and height to a clean ratio, get the decimal, and resize proportionally.
• Ratio Calculator — Solve and simplify any ratio or fraction, including 1080:1350.
• DPI / PPI Calculator — Compare pixel density across image sizes and screens.
• Unit Converter — Convert pixel dimensions into physical print inches and other units.

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This article provides general information for educational purposes. Platform dimensions change; confirm current sizes against the official Instagram help documentation before a major campaign.