Pixel Measurement Tool

An online ruler for original image pixels

A large image may be displayed smaller to fit your screen. This ruler maps your selection back to the decoded image dimensions, so a 100-pixel span remains 100 pixels when you change the zoom. Use it to check icon sizes, screenshot spacing, sprite boundaries, banner dimensions or the margin around a logo. The full image size includes transparent padding as well as visible artwork.

Distance and rectangle measurements

Line reports the straight-line distance between endpoints. Rectangle reports sides and area; Ellipse reports axes and area. Gap measures the separation of two parallel lines whose extent you can adjust. Trapezoid gives you four independently movable corners, labels each side, and reports the span between the top and bottom midpoints plus the enclosed area. Coordinates begin at the top-left edge, with X increasing right and Y increasing downward. A box from X 10 to X 30 is 20 pixels wide. Values on the image are rounded for readability; coordinate fields let you refine the geometry.

A grid with labels you can control

Drag one grid cell to repeat its spacing across the image. Move or resize the cell to change the origin or pitch. Optional X and Y labels count cell offsets from the cell you placed, including negative offsets to its left and above. Customize the grid color, line thickness, opacity and subdivisions separately from the other measurements. Dense grid labels are spaced out for readability, and excessively fine ruling is omitted to keep the image usable. A grid is a guide in image space; setting a plane changes the reported cell measurement but does not warp the grid into perspective.

Calibrate a known length or a plane

Results start in image pixels. Set scale lets you draw a reference line and enter its known length and unit, such as centimetres or inches. That scale applies to objects at the same scale as the reference. Set plane lets you position four corners around a known rectangle and enter its real width and height. Measurements are then calculated on that flat surface, accounting for its perspective. This cannot recover depth or dimensions of objects outside the reference plane. Invalid or incomplete references fall back to pixels and show a message. A measurement crossing the perspective horizon has no finite result and is shown with a dash. Ellipse area under perspective is estimated from its projected outline. Trapezoid height means midpoint-to-midpoint distance; it is not necessarily a perpendicular altitude for an arbitrary four-corner shape.

Customize annotations and keep working

Keep multiple measurements on one image, name them, and add notes or arrows. Drag labels out of the way, shift-drag a label to move its whole shape, or double-click to reset the label position. Customize line and label colors, line thickness, text size, and the halo or background behind text. Undo and redo cover drawing, editing, deleting, calibration and clearing. Your browser remembers the latest measurements for up to 20 images, identified by file content, and remembers your style preferences. Clear all removes the saved measurements for that image; the image itself is never stored by the tool.

Keep the original file intact

Measuring does not resize, crop or rewrite your image. Your selected file stays in browser memory and is not sent to the PixelTools conversion API. Download marked PNG creates a separate full-resolution copy with the shapes, labels, grid and chosen style painted onto it. Copy all measurements produces a text report. You can reopen the same image to resume its saved annotations. SVG artwork needs a raster size before a pixel measurement makes sense; use the SVG to PNG converter first and measure the resulting PNG at the exported dimensions.

Frequently asked questions