PNG Cutter

Uploads a PNG, decodes it onto an off-screen canvas, and slices it into two separate pieces along a straight horizontal or vertical line at a pixel position you choose (like a paper cutter), then lets you download each half individually. A free online tool from Staaarter, right in your browser.

Runs locallyUpdated 2026-07-26

Overview

Introduction

This tool slices a PNG into two separate pieces along a straight line, entirely in your browser, like a literal paper cutter.

It's built directly on the same crop logic the cropper tool uses, just applied twice to produce complementary halves.

What Is PNG Cutter?

A client-side image-slicing tool that reads an uploaded PNG's pixel data and splits it into two new images along a single horizontal or vertical line at a position you choose.

Internally, it computes two crop rectangles, one for each side of the cut line, and extracts both.

How PNG Cutter Works

For a vertical cut, the tool crops everything from x=0 up to the cut position as the first piece, and everything from the cut position to the image's right edge as the second piece; a horizontal cut works the same way along the y-axis instead.

Both crops reuse the exact same rectangle-extraction logic as the standalone cropper tool, since a cut is simply two adjacent crops that together reconstruct the original image.

When To Use PNG Cutter

Use it to split a wide sprite strip, a scanned two-page spread, or a tall infographic into two separate, independently usable images.

It's also handy for quickly dividing an image roughly in half for a side-by-side comparison layout.

Often used alongside PNG Cropper and PNG Canvas Size Changer.

Features

Advantages

  • Runs entirely client-side; the uploaded image is never sent to a server.
  • Produces pixel-perfect halves with no resampling loss, since it's built on exact rectangle crops.
  • Both resulting pieces are immediately downloadable, no extra steps needed.

Limitations

  • Only cuts along one straight horizontal or vertical line per pass; diagonal or multi-segment cuts aren't supported.
  • Produces exactly two pieces per operation; cutting into more requires running the tool again on a resulting piece.

Examples

Split a two-page scanned spread

Input

A 2000x1000 PNG of two scanned pages side by side, vertical cut at x=1000

Output

Two separate 1000x1000 PNGs, one per page

A vertical cut exactly at the midpoint produces two equal-width pieces corresponding to the left and right pages.

Separate a header from a body image

Input

A 800x1200 PNG with a distinct top banner, horizontal cut at y=200

Output

An 800x200 PNG banner and an 800x1000 PNG body

A horizontal cut at y=200 produces a shorter first piece (the banner) and a taller second piece (everything below it).

Cut into a nonstandard, uneven split

Input

A 600x400 PNG, vertical cut at x=450

Output

A 450x400 PNG first piece and a 150x400 PNG second piece

The two resulting pieces don't have to be equal in size; the cut position alone determines the split.

Best Practices & Notes

Best Practices

  • Check the source image's dimensions first so you can choose a meaningful cut position rather than guessing.
  • Use the cropper tool instead if you need one specific rectangle rather than two complementary pieces.

Developer Notes

The lib function computes two crop rectangles from the cut position and orientation and calls cropPng from png-cropper.ts twice, per the category's general 'reuse, don't reimplement' pattern, since a two-way cut is mathematically just two adjacent crops.

PNG Cutter Use Cases

  • Splitting a scanned two-page spread into separate page images
  • Separating a header/banner region from the rest of an image
  • Dividing a wide sprite strip into two usable halves

Common Mistakes

  • Choosing a cut position at the very edge (0 or the full dimension), which leaves one piece empty and is rejected as invalid.
  • Expecting more than two pieces from a single cut; run the tool again on a resulting piece for further splits.

Tips

  • For an arbitrary rectangle rather than a full-width or full-height split, use the cropper tool instead.
  • Note the source image's exact width or height first (via the viewer or dimensions finder) to pick a precise cut position.

References

Frequently Asked Questions