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Thermal / Label Printer diagnostics

Test what the browser can see. Know when it cannot.

Check 4×6 scaling, clipping, barcode sharpness, small text and margins before wasting real shipping labels.

Run these first

Relevant live checks

4×6 Shipping Label Print TestPrint a 4×6-style reference label to inspect thermal/label sizing, clipping, barcode sharpness, and scaling.
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Printer Small Text Test PagePrint small text at several sizes to inspect sharpness, edge quality, smearing, and readability.
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Printer Margin & Clipping TestPrint border references to inspect clipping, scaling, centering, and unexpected page margins.
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First diagnostic sequence

Do the high-signal checks before risky changes

  1. 1

    Confirm exact label size in print settings

  2. 2

    Print DeviceOK 4×6 reference at 100% scale

  3. 3

    Use official calibration for media-sensor issues

What DeviceOK/browser can help check
  • Generate label-sized reference content
  • Expose browser print scaling problems
  • Provide barcode/text sharpness patterns
What this browser page cannot prove
  • Measure printhead temperature or darkness hardware
  • Read every printer's calibration sensor
  • Calibrate media gap sensors generically