popov.link/_includes/reading-time.html

{%- capture words -%}
{{- content | number_of_words | minus: 180 -}}
{%- endcapture -%}

{%- unless words contains '-' -%}
{{- words | plus: 150 | divided_by: 150 | append: ' min read' -}}
{%- endunless -%}