Free Plot Digitizer
Plot Digitizer extracts data points from chart images and PDF figures. Calibrate by clicking two known ticks on each axis, with linear or log scales and rotated scans handled, then click points by hand or extract a curve or markers automatically by color. Export the data as CSV, Excel or tab-separated text for spreadsheets.
- Input:
- Chart images or PDF pages
- Axes:
- Linear or log, 4 reference points
- Export:
- CSV, Excel, tab-separated text
- Price:
- Free
- Runs:
- Locally, in your browser
- Uploads:
- None: files never leave your device
- Account:
- Not needed
Quick answers
Is my image uploaded?
No. The image is read and digitized entirely in your browser; nothing leaves your device.
My scan is slightly rotated. Does that matter?
No. The calibration uses the actual positions of your four reference points, so a rotated or skewed axis is handled correctly.
Processed on your device: your files are never uploaded. How it works
Network activity in this tab
What this page has requested since you opened the site in this tab. An upload is any request that sends data: POST, PUT, PATCH or a request with a body.
No uploads: nothing has been sent from this page.
No network requests yet.
To see every request, open your browser's developer tools (Network tab).
How to use the Plot Digitizer
- Drop a chart image or a PDF (pick the page with the figure).
- Click two labelled ticks on the x axis and two on the y axis, and type their values; turn on log axes if needed.
- Click along the curve to add points, or pick the curve colour and click Extract points.
- Download the data as CSV or Excel, or copy it straight into a spreadsheet.
Credits & open source
Our own code plus open-source libraries. Thank you to the people who make these projects.
- PDF.jsRenders PDF pages to images and thumbnails. © Mozilla Foundation and contributors · Apache-2.0
- ExcelJSReads and writes Excel .xlsx workbooks in the browser. © Guyon Roche and contributors · MIT
Web platform APIs used: Canvas 2D, createImageBitmap, Pointer Events, Clipboard API, File API.
Full license texts: third-party notices · all credits
Frequently asked questions
Can it read logarithmic axes?
Yes. Turn on Log x or Log y and type the tick values as they are printed (for example 1 and 1000).
The automatic extraction picks up gridlines or text.
Draw a search area around the curve, lower the colour tolerance, or remove the stray points by clicking them.
How accurate is it?
About one pixel of the image: zoom in with the magnifier when clicking references, and choose reference ticks far apart.