Open an image. Set the scale. Measure.
Download lengto.exe · Quick guide · Python examples
Windows 10/11 x64 · About 3.5 MB · No installation
lengto measures real distances on scanned plans, technical photographs and microscope images. All you need is a known reference length and a single executable.
Application render using a synthetic drawing.
- Open or paste. TIFF, PNG, JPEG and PDF, including multipage documents. Paste images with Ctrl+V.
- Calibrate and measure. Pixel snapping, flexible units and editable measurement labels.
- Save the result. Export annotated images or PDFs; include all pages in TIFF/PDF.
- Repeat the work. Record editable Python macros and apply them to other images or whole folders.
- Download and run lengto.exe. Open, drop or paste an image.
- Choose Measurements → Calibrate, enter a known length and click its endpoints.
- Choose Measure, click endpoint pairs, then File → Export to save. Esc ends the tool.
Every recorded point keeps its pixel coordinates, relative position and source color. Edit the macro to find colored features, repeat measurements or process a folder. Relative coordinates adapt to resized images with matching framing; RGB searches let your script choose new endpoints.
Python 3.8+ is needed only to run macros. Measuring and recording need nothing extra.
Know the limits: one uniform scale per document; no perspective correction. Exports flatten annotations and use preview resolution. Keep the source and a macro to reproduce your work.
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MIT license · © 2026 Ivan Panzera. Bundled components retain their own licenses.