Features
Feature explanations for accurate angle measurement, practical workflows, and more reliable results
These features are designed to work together, not as a checklist. Upload a diagram or photo, align one or more protractors, verify the inner or outer reading, and export a record when you need to review or share the result. The core tool is free in the browser, and optional sign-in is only needed for account-based features such as the one-time ad-free upgrade.
Ray-Based Angle Measurement
Place rays directly from the protractor center to measure the angle you actually want to read, then switch between degrees and radians, inner and outer angles, and decimal precision. This is useful when you need to verify homework, compare diagram annotations, or check whether a drawing matches an expected value instead of relying on a rough visual estimate.
Image Upload & Overlay
Upload photos, worksheets, screenshots, blueprints, or technical diagrams and measure directly on top of them. Opacity, resize, and rotation controls help you line the protractor up with the source image more carefully. For best results, use clear images with minimal perspective distortion, because blurry or heavily angled photos can reduce measurement confidence.
Multiple Protractors
Use multiple protractors when one image contains several corners, reference lines, or competing measurements. This is especially helpful for design layouts, engineering sketches, and teaching examples where you want to compare angles side by side instead of resetting the workspace every time.
Flexible Export Options
Export measurements in CSV when you need a simple record, save JSON when you want to reopen the full workspace later, and use PNG or JPEG when you need a visual result for sharing or documentation. Exporting is useful for review, reporting, lesson prep, or checking a measurement again after you step away from the task.
Undo & Redo
Undo and redo let you experiment without losing your place. If you move a protractor, rotate an image, or adjust the wrong ray, you can quickly step backward and compare versions instead of rebuilding the whole setup. This is especially useful while learning the tool or refining a precise reading.
Grid & Ruler Overlays
Grid and ruler overlays help you align baselines, compare positions, and reduce visual guesswork on crowded images. They work best as reference aids rather than proof of accuracy, so if the source image is distorted or off-angle, use them together with zoom and careful ray placement.
Angle Snapping
Angle snapping helps when you expect common values such as 30°, 45°, or 90°, or when you want cleaner repeated constructions. It can speed up classroom demos and design checks, but it is best turned off when you need to inspect an irregular angle rather than force it toward a preset increment.
Keyboard Shortcuts
Keyboard shortcuts keep repeated measurement work moving quickly. Switch tools, undo changes, and clean up selections without leaving the canvas, which is especially useful when you are checking many angles in one worksheet, diagram set, or annotated image.
View Controls
Zoom and pan controls help you inspect small vertices, crowded intersections, and low-contrast image details before committing to a reading. They make alignment easier, but they do not fix poor source quality, so combine them with clear images and careful center placement for the most reliable results.
Customizable Display
Adjust colors, scale, rotation, and display settings so the protractor stays readable against dark photos, bright diagrams, or busy layouts. These controls are most valuable when you are presenting measurements to others or comparing several angles in the same workspace.
Lock Objects
Lock finished protractors, rays, or images when one part of the workspace is already correct and you only want to adjust the rest. This reduces accidental edits and makes it easier to compare a stable reference angle with a second measurement.
Private & Secure
Most measurement work happens locally in your browser, so uploaded images and angle adjustments stay on your device during normal use. If you choose optional sign-in or buy the one-time ad-free upgrade, we store only the limited account and payment-status information needed for those features. See the Privacy Policy for details.
Ready to use these features on real measurements?
Start with the free core tool in your browser, then use tutorials if you want more guided workflows. Sign in only if you need account-based features or the optional one-time ad-free upgrade.