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1:1 Calculator

PhotographyPhotography Planning

Width of the original photo or frame.

Height of the original photo or frame.

Largest 1:1 crop —
Square side (px)
—
Share of the image kept
—
Square size (MP)
—
Centred crop offset
—
Original ratio
—

A 1:1 crop is a square whose side equals the shorter edge of the original frame. A 6000 × 4000 photo from a 24 MP camera crops to 4000 × 4000, which keeps 66.7% of the pixels (16 MP). To centre it, start the crop 1000 px in from the left edge.

About this tool

Square crops turn up everywhere in photography: profile pictures, grid posts, album covers, product shots for marketplaces and medium-format 6×6 looks. Getting there from a 3:2 or 4:3 file means deciding how much of the frame to throw away. Enter the width and height of the original image in pixels and the calculator returns the largest square that fits, the offsets that centre it, how many megapixels remain and what fraction of the original frame survives. The working is shown line by line so you can repeat it for a print layout. It assumes a centred crop with no resampling; if you want the subject off-centre, keep the same square side and move the offset yourself, and it cannot tell you whether the composition still works once the edges are gone.

How to use it

  1. Enter the width

    Type the pixel width of the original file, as shown in your editor or the file's EXIF data.

  2. Enter the height

    Type the pixel height. Portrait and landscape both work; the shorter edge becomes the square side.

  3. Read the crop

    The headline shows the square size; the offsets tell you where to place a centred crop box.

  4. Check what is lost

    Use the kept share and megapixels to judge whether the square is large enough to print or upload.

Examples

6000 × 4000 camera file

Image width
6000
Image height
4000

Result Largest 1:1 crop: 4000 × 4000
Square side (px): 4,000
Share of the image kept: 66.7%
Square size (MP): 16
Centred crop offset: left 1000 px, top 0 px
Original ratio: 1.5 : 1

  1. Square side = min(6000, 4000) = 4000 px
  2. Horizontal offset = (6000 − 4000) ÷ 2 = 1000 px; vertical offset = (4000 − 4000) ÷ 2 = 0 px
  3. Area kept = 4000² ÷ (6000 × 4000) = 66.7%

A 24 MP landscape frame from a 3:2 sensor loses a third of its width when cropped square, leaving a 16 MP image.

4:5 portrait post

Image width
1080
Image height
1350

Result Largest 1:1 crop: 1080 × 1080
Square side (px): 1,080
Share of the image kept: 80%
Square size (MP): 1.17
Centred crop offset: left 0 px, top 135 px
Original ratio: 0.8 : 1

  1. Square side = min(1080, 1350) = 1080 px
  2. Horizontal offset = (1080 − 1080) ÷ 2 = 0 px; vertical offset = (1350 − 1080) ÷ 2 = 135 px
  3. Area kept = 1080² ÷ (1080 × 1350) = 80%

Turning a 1080 × 1350 portrait post into a square trims 135 px from the top and bottom.

12 MP phone photo

Image width
4032
Image height
3024

Result Largest 1:1 crop: 3024 × 3024
Square side (px): 3,024
Share of the image kept: 75%
Square size (MP): 9.14
Centred crop offset: left 504 px, top 0 px
Original ratio: 1.333 : 1

  1. Square side = min(4032, 3024) = 3024 px
  2. Horizontal offset = (4032 − 3024) ÷ 2 = 504 px; vertical offset = (3024 − 3024) ÷ 2 = 0 px
  3. Area kept = 3024² ÷ (4032 × 3024) = 75%

A 4032 × 3024 phone shot keeps three quarters of its pixels as a 3024 px square.

How it is calculated

S = min(W, H); offset x = (W − S) ÷ 2; offset y = (H − S) ÷ 2; kept = S² ÷ (W × H) × 100

W
original width in pixels
H
original height in pixels
S
side of the largest 1:1 square
kept
percentage of the original pixels inside the square

A 1:1 aspect ratio means width equals height, so the biggest square that fits inside a rectangle is limited by its shorter edge. The longer edge is trimmed equally from both sides to centre the crop. The share kept equals the short edge divided by the long edge, so a 3:2 frame always keeps 66.7% and a 4:3 frame keeps 75%, whatever the resolution.

When not to use it

  • For other target ratios such as 4:5 or 16:9, use an aspect ratio calculator instead.
  • It does not plan print sizes in inches or centimetres at a given DPI.
  • It cannot judge whether the subject survives a centred crop.

Common mistakes

  • Entering a resized preview's dimensions instead of the full-resolution file.
  • Assuming a square crop of a 24 MP file is still 24 MP; a 3:2 frame drops to 16 MP.
  • Forgetting that rotated phone photos may report width and height swapped in EXIF.

Frequently asked questions

What does a 1:1 aspect ratio mean?

The width and height are equal, so the image is a perfect square. 1080 × 1080, 2000 × 2000 and 4000 × 4000 are all 1:1, regardless of resolution.

How much of a 3:2 photo is lost when cropping square?

One third. The square side equals the short edge, which is two thirds of the long edge, so 66.7% of the pixels remain. A 6000 × 4000 file becomes 4000 × 4000.

What size should a square Instagram post be?

Instagram displays square posts at 1080 × 1080 pixels. Any larger 1:1 file is scaled down; a file smaller than 1080 px on a side is scaled up and can look soft.

How do I centre the square crop?

Trim half of the difference between the long and short edges from each end. For a 4032 × 3024 photo, the difference is 1008 px, so the crop starts 504 px from the left.

Can I crop square without losing resolution?

Only by adding canvas instead of cutting: pad the short edge with a border until it matches the long edge. That keeps every original pixel but adds blank or coloured bars.

Which cameras shoot 1:1 natively?

Medium-format film cameras using 6×6 cm frames, such as many twin-lens reflexes, shoot square. Many digital cameras and phones offer a 1:1 mode, which simply crops the sensor's 3:2 or 4:3 frame.

Cite this tool

Using this tool in an assignment, article or report? Copy a citation, or a link for your website.

APA

Tools Directory Editorial Team. (2026, October 9). 1:1 Calculator. Tools Directory. Retrieved October 27, 2026, from https://tools.milunir.com/photography/photography-planning/1-1-calculator/

MLA

Tools Directory Editorial Team. “1:1 Calculator.” Tools Directory, 9 Oct. 2026, https://tools.milunir.com/photography/photography-planning/1-1-calculator/. Accessed 27 Oct. 2026.

Chicago

Tools Directory Editorial Team. “1:1 Calculator.” Tools Directory. Last modified October 9, 2026. Accessed October 27, 2026. https://tools.milunir.com/photography/photography-planning/1-1-calculator/.

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