Data · charts
Turn a chart image into data.
Calibrate the axes, click the points you need and download a clean CSV. No uploads, no account, no spreadsheet gymnastics.
Chart image
PNG, JPG or WebP up to 20 MB. The image stays in your browser.
Upload a chart image to begin.
Axis calibration
Pick two points on the x-axis and two on the y-axis, then type the value at each.
X1 and X2 need different horizontal positions; Y1 and Y2 need different vertical positions. Values can be negative or decimal.
Data points
0 capturedGood to know
The result is a guide, not a guarantee.
This calculator runs entirely in your browser. Check the assumptions, keep the inputs realistic, and use the result as a starting point for a decision.
Use a high-resolution image and calibrate over the widest readable axis range. Log scales and multi-axis charts are not supported.
What does a plot digitizer do?
It turns a picture of a chart into numbers. You mark known positions on the x and y axes, then click the data points you need. The tool converts each click into the chart's data coordinates and lets you export them as CSV.
How do I calibrate the axes?
Pick two points on the x-axis and type the value at each, then do the same for the y-axis. Use points that are far apart and easy to read, such as labelled tick marks. The tool needs different horizontal positions for X1 and X2, and different vertical positions for Y1 and Y2.
Does it support logarithmic axes?
No. This version assumes linear axes. A log-scale chart would need a different calibration formula, so do not use these results for log plots without converting them yourself.
How accurate are the extracted points?
Accuracy depends on image resolution, how precisely you place the calibration points and how clearly the data points are drawn. Zoom in, calibrate across the full axis range and place the marker on the centre of each plotted point. Treat the result as an estimate, not the original data.
What does the CSV contain?
The file has two columns, x and y, with one row per captured point. Values use up to eight significant digits and switch to exponent notation for very large or very small numbers.
Is my chart image uploaded?
No. The image is loaded and drawn on a canvas in your browser. It is never sent to simplytools.us or a third party, and no copy is stored after you leave the page.
Can I capture more than one series?
The tool keeps one point list. If a chart has several series, capture them in order and use the row numbers to separate them in your spreadsheet, or export one series at a time by clearing the points between runs.