Fluorescence micrograph
Fluorescent cells with a 10 µm scale bar.
Fluorescence · 0.1 µm/pixel · 10 µm bar
Microscopy Scale Bar Generator
FigranAdd a calibrated microscopy scale bar to an image without changing the original file.
- µm per pixel or known length
- Original file unchanged
- PNG, SVG or overlay only
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Microscopy scale bar examples
Explore calibrated scale bars for common microscopy images.
Brightfield histology
A labeled bar on a tissue-like brightfield image.
Brightfield · 0.325 µm/pixel · 100 µm bar
SEM scale bar
A short nanometre bar over particle-like structures.
SEM · 4.8 nm/pixel · 500 nm bar
Stage micrometer calibration
A micrometer scale bar example for known-length calibration.
Stage micrometer · 1 µm/pixel · 50 µm bar
16-bit TIFF with ImageJ calibration
A grayscale image with a 12-bit effective range.
16-bit TIFF · ImageJ calibration · 50 µm bar
Low-magnification specimen
A millimetre bar on a whole specimen.
Low magnification · 8 µm/pixel · 1 mm bar
How to add a scale bar to a microscope image
Calibrate your image, style the scale bar and export your figure.
1Open an image
Choose an image or drop it onto the preview.
2Calibrate
Enter pixel size or draw a known length to calibrate the scale bar.
3Style the bar
Choose the microscopy scale bar length, position, color and label.
4Download
Download a PNG, SVG or an overlay.
Calibrate microns per pixel
Convert pixels to microns (microns per pixel) using a known sample scale or a nominal camera estimate.
Pixel size
µm/px = known pixel size
Known length
µm/px = length ÷ line pixels
Camera and objective
µm/px = camera pixel size × binning ÷ total magnification
For a 6.5 µm camera pixel and 1× additional magnification:
| Objective | 10× | 20× | 40× | 60× | 100× |
|---|---|---|---|---|---|
| µm/px | 0.65 | 0.325 | 0.1625 | 0.1083 | 0.065 |
Use a stage micrometer for measurement calibration.
What changes in the image
| Export | Dimensions and pixels | Use |
|---|---|---|
| PNG | Original dimensions; bar and label are composited | Ready-to-use figure |
| SVG | Original dimensions; image embedded with vector bar | Vector editing |
| Overlay | Original dimensions; transparent outside the overlay | Keep the original image separate |
For 16-bit input, the composite uses an image-wide linear mapping to 8-bit. Keep the original data and record your processing: Rossner and Yamada (2004), Cromey (2010), Jambor et al. (2021).
Scale bar FAQ
What is a scale bar on a microscope image?
A microscopy scale bar represents a known physical length, so readers can judge the size of features in biology images even after resizing.
How do I add a scale bar in ImageJ or Fiji?
For an ImageJ scale bar, use Analyze › Set Scale to enter a known distance and unit, then Analyze › Tools › Scale Bar. This tool can read ImageJ calibration from TIFF metadata.
How do I convert pixels to microns?
Multiply the number of pixels by the calibrated microns per pixel. Use a pixel size, a known length, or a camera and objective estimate to obtain the scale.
What length should the scale bar be?
Choose a microscopy scale bar length of 1, 2 or 5 × 10ⁿ units that occupies about 10–20% of the image width. Identify differing bar lengths in the figure legend.
Can I calculate the scale from the objective magnification?
Yes, estimate µm per pixel as camera pixel size × binning ÷ total magnification. An adapter changes total magnification; a stage micrometer gives a more reliable calibration.
Does it work with 16-bit TIFF files and OME-TIFF?
Yes, baseline 8- and 16-bit TIFF first pages are supported, including ImageJ and OME calibration. The 16-bit display is linearly mapped to 8-bit for composite PNG; use an overlay to retain the original data.
Does adding a scale bar change my image?
A composite PNG changes the pixels covered by the bar and label, without changing image dimensions. Download an overlay to keep the original file untouched. Transparent WebP and 32-bit BMP must first be exported as PNG or TIFF so their pixel values can be preserved.
Is my image uploaded?
No. The image stays in your browser and is not retained when you close the page.
Add a scale bar
Calibrate your microscope image and download a scale bar.