Art tools
Proportion ruler
Load a reference image, then drag over it to measure a length in pixels or read a slope in degrees. The picture never leaves your browser.
How it works
Artists constantly measure: hold up a pencil, mark a length with the thumb, then compare that unit to everything else in the scene. This tool brings that habit on-screen. Load a reference image and drag a ruler across it to measure a length in pixels, then drag it again elsewhere to compare - "the head is one unit, the body is seven". An angle finder lets you lay a line over an edge and read its slope in degrees, so you can match the tilt of a shoulder, a roof, or a horizon.
Everything is drawn over your image on a canvas and computed in your browser, so the reference never leaves your machine. It is a lightweight sight-size and comparative-measurement aid for studying any photo.
Example. Drag the ruler down the face from hairline to chin and note it reads 120 px. Drag it down the whole figure: 840 px. That is a seven-heads-tall proportion. Then drop the angle finder on the shoulder line and read 12 degrees.
FAQ
What can I measure?
A length in pixels with the ruler, and an angle in degrees with the angle finder. Comparing one measured length to another gives you proportions, which is what matters most when drawing from a reference.
What is sight-size and comparative measurement?
Comparative measurement picks one length as a unit (often the head) and expresses everything else in those units. Sight-size matches your drawing to the reference at the same visual size. Both rely on measuring and comparing, which this tool makes quick.
Does it measure real-world units?
It measures in pixels of the loaded image. Because drawing from a reference is about ratios, not absolute units, comparing two pixel lengths gives you the proportion you need directly.
Is my reference uploaded?
No. The image is drawn and measured entirely in your browser on a canvas. Nothing is sent to a server, so it works offline and your references stay private.