Online Protractor: Measure Angles on Photos & Screenshots
Free online protractor for photos and screenshots. Align with snap + grid, then export PNG/PDF or CSV/Excel/JSON. For PDFs, take a screenshot first.
Initializing protractor...
Settings & Controls
Protractors
Mode
Position & Scale
Rotation
Actions
Color Presets
Custom Colors
Snap
Guides
Grid
Background Image
Upload an image to measure angles on top of it.
Measurements
0Features
Built for accurate angle measurement
Align images fast, snap to clean angles, add measurement points, and export results you can share or reuse.
- Upload or paste an image
Upload, drag & drop, or paste from your clipboard to start measuring immediately.
- Fix the image before measuring
Rotate, flip, move, and scale the background, and adjust brightness/contrast for clearer edges.
- Snap for cleaner readings
Snap to common angles (30°, 45°, 90°, 120°, 180°) or a fixed step (1°, 5°, 10°).
- Angle guides
Add multiple color-coded guide lines at specific angles and toggle visibility while you work.
- Grid overlay
Use square/dot grids with adjustable spacing, color, and opacity to align to edges and axes.
- Readable colors
Choose presets or custom colors for lines, inner/outer scales, and measurement points.
- Multiple protractors, 180° or 360°
Add more than one protractor, switch between them, and use 180°/360° modes for reflex angles.
- Measurement points and derived values
Keep a list of points with angle type, coordinates, complementary/supplementary angles, and radians.
- Undo/redo and quick resets
Experiment freely, then undo/redo, reset position, or clear points and guides to restart fast.
- Export results
Download PNG/PDF for sharing, and export measurement data as CSV/Excel/JSON for reports.
What is an online protractor?
An online protractor tool (digital protractor) that runs in your browser. Place one or more protractors on an image, add measurement points, and export a shareable report.
Works for
- Photos from a phone or camera
- Diagrams, drawings, and technical sketches
- Screenshots and UI mockups
- Homework and geometry practice
- Design review and QA checks
- Construction notes and quick measurements
Controls you get
- 180° and 360° protractor modes
- Multiple protractors per image
- Snap to common or step angles
- Guide lines for reference directions
- Square/dot grid overlays
- Color presets and custom colors
Outputs you can export
- PNG image for sharing
- PDF report with the screenshot and data
- CSV for spreadsheets
- Excel (XLSX) export
- JSON for structured saving
- Supports JPG/PNG/GIF/SVG/WEBP inputs
For best accuracy, straighten the image first (rotate/flip/grid/contrast), then use snap and guides for consistent readings.
How to use it
- 1Add an image
Upload a photo/diagram, drag & drop a file, or paste an image from your clipboard.
- 2Align the background
Rotate or flip the image, adjust brightness/contrast, and use the grid to line up edges.
- 3Place the protractor
Choose 180° or 360°, position the center (X/Y), adjust radius, rotate with Snap (common/step), and use quick angles (30/45/90/120/180) when helpful.
- 4Add measurement points
Click to add points, review the list (angle type, coordinates, complementary/supplementary, radians), and edit if needed.
- 5Export and reuse
Download PNG/PDF for sharing, or export CSV/Excel/JSON to reuse the data elsewhere.
Learn more
Short tutorials and reference pages to help you measure faster and export cleaner results.
Why Smart Protractor
- Made for accuracy
Grid alignment, snap modes, and guides help you get clean readings on real images.
- Privacy-friendly
Your image stays in your browser session—no account required.
- Fits different tasks
Use it for homework, design review, construction photos, and diagrams.
- Data you can actually use
Export PNG/PDF for sharing, plus CSV/Excel/JSON for spreadsheets and reports.
- You stay in control
Undo/redo, quick resets, and multiple protractors help you iterate without losing your place.
Frequently Asked Questions
- Upload, drag & drop, or paste the image. If needed, rotate/flip and adjust brightness/contrast first, then place the protractor center on the vertex, align the baseline to one side, and rotate until the other side lines up.
- Both terms fit. It runs in the browser like a virtual protractor, with digital controls like 180°/360° modes and multiple protractors.
- Snap helps you land on clean angles. Use common angles for quick work, or a step mode (e.g., 1°, 5°, 10°) when you need a controlled adjustment.
- Yes. Export PNG for quick sharing, generate a PDF report, or export data as CSV/Excel/JSON for spreadsheets and reports.
- Yes. Take a photo on your phone and upload it here (JPG/PNG/GIF/SVG/WEBP supported). A larger screen can make fine alignment easier.
- The tool runs in your browser. Your image is used to render the canvas and isn’t required to be uploaded for measuring.
- Switch between the 180° and 360° modes. For angles over 180° (reflex angles), use 360° and align the baseline the same way.
- Photos can have perspective distortion. For best results, shoot as straight-on as possible, then use background rotation/flip, brightness/contrast, and the grid to help alignment.
- Guides are reference lines you can add at specific angles. Add several, toggle visibility, and use them as stable baselines when you measure multiple edges.
- Use a larger spacing on low-detail photos and a smaller spacing on diagrams. Choose square or dot grids and lower opacity so the grid helps without covering your lines.
- Yes. Add multiple protractors, add measurement points, and review everything in the Measurements list. You can also edit point coordinates, and undo/redo if you make a mistake.
- Use the controls to reset protractor position, clear points, clear guides, reset image adjustments, or clear/replace the image. The Quick Start Guide toggle is also there when you need a refresher.