Convert font ".otf" for LVGL


I need to use the offline converter “” to convert a “.otf” font.
Unfortunately the examples for command sets on the homepage are quite complex.

I have the font “monofonto rg.otf” and now I want to convert it to a C-file (for LVGL), 20 pixel height and 1bit per pixel.
How should the command look like?

Maybe like this?:
lv_font_conv --font monofonto rg.otf --size 20 --format lvgl --bpp 1 -o monofonto rg.font ?

What does 0x20-0x7F actually mean? I just need the abc to Z + numbers dot, colon and comma…



  1. Convert OTF to TTF: OTF to TTF (Online & Free) — Convertio
  2. 0x20-0x7F means the character codes. You can check with Glyphr Studio by loading TTF: Glyphr Studio
  3. Run lv_font_conv on TTF with CLI arguments you want:

If font file name contains whitespace, then do not forget to put it into double quotes, otherwise lv_font_conv will not recognize arguments correctly!

lv_font_conv --font "monofonto rg.ttf" --output "monofonto rg.font" --bpp 1 --size 20 --format bin --range 0x21-0x7E --no-compress --no-kerning

Thank you very much for your help. Do I really need to convert OTF to TTF? According lv_font_conv it should also support otf, see:

Converts TTF/WOFF/OTF fonts to compact format , suitable for small embedded systems.

I receive following error:

BTW: With the online converter it works…