Thermal / Receipt Printer Test
Print a receipt-width thermal test strip.
Print settings
Print this on the paper you normally use, then examine each section. What a healthy result looks like is described above each pattern on the sheet.
RunTheTests Thermal / Receipt Printer Test · print at 100% · plain paper
Grayscale — 0% to 100% in 10% steps
Text sharpness — decreasing sizes (all should be crisp and readable)
12pt — The quick brown fox jumps over the lazy dog. 0123456789 iIlL1 oO0
9pt — The quick brown fox jumps over the lazy dog. 0123456789 iIlL1 oO0
7pt — The quick brown fox jumps over the lazy dog. 0123456789 iIlL1 oO0
5pt — The quick brown fox jumps over the lazy dog. 0123456789 iIlL1 oO0
4pt — The quick brown fox jumps over the lazy dog. 0123456789 iIlL1 oO0
Resolution — line pairs at decreasing spacing (should stay distinct)
How this test page works
A narrow test strip for thermal receipt and label printers, checking print darkness, text legibility and fine detail across the paper width.
What the results mean
- Print darkness
- Thermal output fades if the head temperature or paper sensitivity is off. The density steps show whether darkness is even.
Common problems and fixes
- A thin white line runs down every receipt in the same place
- A dead printhead element. It stays in the same position, does not move between prints, and does not recover with cleaning — the head needs replacing. Distinguishing this from a smudge takes one wipe with isopropyl alcohol: if the line survives a clean head, it is the element.
- Print fades within weeks of being stored
- That is thermal paper behaving normally rather than a printer fault. The coating darkens with heat and continues to react to heat, light and some plastics, so receipts kept in a warm car or a PVC wallet fade fast. Anything that must last needs a scan or a copy, not better print settings.
- Output is faint across the whole strip
- Raise the darkness or density setting first, which is the cause most of the time. If that does not fix it, clean the head with isopropyl alcohol on a lint-free swab, then check the paper — thermal stock comes in different sensitivity grades, and a roll that does not match the printer's setting prints light however hard it is driven.
Frequently asked questions
My thermal prints are faint
Either the print density setting is too low, or the thermal paper is old or the wrong sensitivity grade. Raise the density in the printer settings first, then try fresher paper.
Why is there no ink in a thermal printer?
Because the paper carries the chemistry. A thermal head heats tiny elements against a coated stock, and the coating darkens where it is heated — so there is no ink, no toner and no ribbon, and the only consumable is the paper itself. It is also why the print fades: the reaction that made the image can keep going.
How do I know whether the head or the paper is at fault?
Change the roll first, since it is the cheaper test. A fresh roll of the correct sensitivity grade that prints cleanly settles it. If the fault survives new paper and a cleaned head, and it is a line in a fixed position, the head has a failed element and no setting will bring it back.