Every calibration target
- Checkerboard
- ChArUco
- ArUco
- Circle grid
calibrx.io · 7×5 squares · 25/18 mm · DICT_6X6_250
Pattern generator
ChArUco board & camera calibration pattern generator
Generate a free, printable checkerboard, ChArUco board, ArUco board, or circle-grid target in exact millimetres. Choose A4, Letter, A3, or a custom page, preview it live, and download a print-accurate PDF, SVG, or PNG for CalibrX and OpenCV camera calibration.
Generate any board
Printable camera calibration targets for every workflow
Every target is generated in physical units, not approximate screen pixels, so its dimensions remain measurable after printing.
Recommended
Free ChArUco board generator
Create a ChArUco calibration board with selectable OpenCV dictionary, start ID, square size, and marker size. Unique marker IDs allow useful corners to be recovered from partial or occluded views.
Marker grids
ArUco board generator
Generate an ArUco GridBoard from real OpenCV dictionaries such as DICT_4X4_50, DICT_5X5_100, and DICT_6X6_250. Control marker spacing and IDs for pose estimation or calibration.
Classic target
Checkerboard pattern generator
Build a chessboard calibration target with exact rows, columns, and square dimensions. Checkerboards provide precise inner corners for controlled monocular and stereo calibration captures.
Machine vision
Circle-grid pattern generator
Create symmetric or asymmetric dot patterns with accurately spaced circle centers. Circle grids are useful when centroid detection is more reliable than sharp corner detection.
Print accurately
How to generate a calibration board
- Choose the target type. Use ChArUco for robust general calibration, checkerboard for controlled captures, ArUco for marker grids, or circles for centroid-based detection.
- Enter physical dimensions. Set rows, columns, square or marker size, and the OpenCV dictionary where applicable.
- Select the page. Fit the board to A4, Letter, A3, or a custom surface while preserving its real dimensions.
- Download and print. PDF is best for ordinary printing; SVG is ideal for fabrication; PNG is convenient for digital use.
Compare
Which calibration pattern should you use?
| Pattern | Best for | Corner accuracy | Partial / occluded views | Notes |
|---|---|---|---|---|
| Checkerboard | Simple, controlled setups | Highest | Must be fully visible | The classic target; every inner corner must be seen in each frame. |
| ChArUco | Most calibrations (recommended) | High | Robust | Checkerboard corners plus ArUco IDs — keeps sub-pixel accuracy even when partly out of frame. |
| ArUco | Cluttered or partial views | Medium | Robust | Each marker is identified individually, so occlusion is tolerated. |
| Circles grid | Industrial / machine vision | High (centroids) | Must be fully visible | Symmetric or asymmetric; sub-pixel centers but sensitive to strong perspective. |
FAQ
Calibration patterns — common questions
What is the best camera calibration pattern?
For most cameras a checkerboard or ChArUco board is the best starting point — they give accurate corners and are easy to detect. Use ChArUco when the board may be partly out of frame, ArUco grids for multi-marker setups, and circle grids when you want sub-pixel centroids in slightly blurry images.
What's the difference between a checkerboard and a ChArUco board?
A checkerboard needs the full board visible to detect all corners. A ChArUco board adds unique ArUco markers inside the white squares, so it can still be identified and used for calibration even when partially occluded or cut off at the edges.
ChArUco vs ArUco — which should I use?
A ChArUco board is a checkerboard fused with ArUco markers and gives the most accurate corners. A plain ArUco grid is a set of standalone markers — handy for partial views and pose estimation, but a ChArUco board is usually more accurate for intrinsic camera calibration.
What size should calibration pattern squares be?
Make the board large enough to fill a good part of the frame at your working distance — typically 15–35 mm squares printed on A4/Letter or larger. The generator shows the exact board size in millimetres; enter that real-world size in CalibrX so the scale is correct.
How do I print a calibration pattern correctly?
Print at 100% / "actual size" (disable "fit to page" or "scale to fit"), then measure the 50 mm scale bar with a ruler to confirm it matches. Mount the print flat on a rigid, non-glossy surface — any bend or ripple adds calibration error.
Are these patterns compatible with OpenCV?
Yes. The generator uses the real OpenCV ArUco dictionaries, so every checkerboard, ChArUco, ArUco, and circle-grid target detects in OpenCV — or upload your photos of the printed board to CalibrX and calibrate online without writing any code.
These targets follow the pattern geometry used by OpenCV. Read the official OpenCV calibration-pattern guide or continue with the CalibrX online calibration workflow.
Reviewed by the CalibrX engineering team · Updated August 2026.