How does Angle Finder detect angles?

Angle Finder finds strong image edges, converts them into straight line segments, calculates valid intersections, and measures the angles between those lines.

Do uploaded images leave my device?

No. Images are decoded, analyzed, and exported locally in your browser.

How accurate are measurements from an image?

Accuracy depends on image sharpness, camera perspective, lens distortion, visible line quality, and manual adjustments.

Can I add an angle manually?

Yes. The Add angle tool lets you place a first side point, vertex, and second side point, then refine the measurement by dragging points.

Private image analysis

Find angles in any image

Detect intersecting lines, refine the measurements, and export an annotated copy—all on your device.

Start a new measurement

Upload an image to find angles

Use a clear photo, plan, diagram, or screenshot. JPG, PNG, and WebP up to 15 MB.

Drop an image herePaste from clipboardTake a photo

Next stepChoose an image

Upload a photo or try the built-in sample.

—Lines

—Intersections

—Angles

—Confidence

Filter Sort

No measurements yet

Upload an image, then run automatic detection or add an angle manually.

Export resultsImage or measurement data

Your images stay on your device and are not uploaded to a server.

About Angle Finder

A practical way to measure angles from images

Angle Finder combines automatic line detection with precise manual controls, giving you a useful starting point without taking away your ability to correct the result.

Made for real-world visual measurement

Use photos, screenshots, plans, sketches, and technical drawings to inspect an angle without installing specialist software. It is useful for learning, woodworking, drafting, design reviews, architecture, DIY projects, and quick on-site checks.

01
Automatic first passProminent lines and intersections are detected for you.
02
Manual precisionAdjust endpoints or place a three-point angle yourself.
03
Private by designYour image is processed locally and never uploaded.

How it works

1
Open an imageUpload, drop, paste, capture, or use the sample.
2
Detect the geometryEdges become line segments and valid intersections.
3
Review and refineSelect results, move points, or change detection settings.
4
Export your workSave an annotated image or structured result data.

For the clearest result Use a sharp image photographed straight-on, with good contrast and the relevant edges fully visible.

Geometry learningWoodworkingFloor plansTechnical drawingsDIY projectsDesign reviews

Frequently asked questions

Helpful answers before you measure

Still unsure? Open the in-app Help guide for image tips and manual editing instructions.

How does automatic angle detection work?

The app converts the image to grayscale, reduces noise, finds strong edges, and uses line detection to identify straight segments. It then calculates valid intersections, measures the angles between line vectors, removes duplicate results, and assigns a confidence score.

Do my uploaded images leave my device?

No. Uploads, camera captures, detection, perspective correction, and exports happen locally in your browser. Angle Finder does not send your image to an analysis server or store it in browser preferences.

Which image formats can I use?

You can use JPG, JPEG, PNG, and WebP images up to 15 MB. Clear, high-resolution images with strong visible edges usually produce the best automatic results.

How accurate are measurements from a photograph?

The geometry calculation is precise for the points and lines shown, but the image itself may introduce error. Camera perspective, lens distortion, blur, shadows, and thick or unclear edges can all affect the result.

What should I do if no angles are found?

Try a detection preset that better matches the image, raise edge sensitivity, lower the confidence threshold, or reduce the minimum line length. You can always use Add angle to place the measurement manually.

Can I correct an automatic result?

Yes. Select a detected line or angle, drag its endpoint handles, move the intersection, rename the result, hide it, or delete it. Undo and redo are available for manual changes.

When should I use perspective correction?

Use it for a flat rectangular surface—such as a sheet, sign, or floor plan—photographed at an angle. Select its four corners clockwise from the top-left, apply the correction, and run detection again.

Can I use Angle Finder for safety-critical work?

Not as the sole measurement source. For engineering, construction, manufacturing, medical, or other safety-critical decisions, verify the result with appropriate certified equipment and qualified professional review.