Rendering & DPI

How source and target DPI control the size and sharpness of a rendered label.

In One Paragraph#

ZPL is authored for a specific printer resolution (its source DPI, commonly 203). When you render, you choose a target DPI — match it to the printer you'll actually print on. The engine scales the layout from source to target so a 4×6" label stays 4×6" regardless of DPI.

The Scale-Ratio Warning#

A target DPI far below the source (a ratio over ~2.5×) produces a DpiScaleFloorApplied warning in the response's warnings array — the layout still renders, but very small elements may lose fidelity. Your plan also caps the maximum DPI you may request; exceeding it returns 403 DpiNotPermitted.

Threshold vs Preview#

The threshold flag controls how the engine rasterizes: true renders a hard black/white (thermal-fidelity) image like a real printer; false (the default) is an anti-aliased preview that looks smoother on screen.

Font Profiles#

Built-in text can be rendered with one of four font_profile families — dejavu, inter, plex, roboto — to match your house style.