Custom character sheet HTML maths functions?

Unsure if this is the right topic but it seemed to make the most sense. So I'm currently making a custom character sheet and one of the sections in it is about 20% max health. Is there any way to make it work it out 20% max health automatically using HTML or will players just have to do it manually and write it in? I appreciate that is isn't hard to work out 20% but it'd be nice to make the sheet do it. It's been years since I used HTML so it's been a bit of a rollercoaster lol Thanks in advance :)

This would be best done with a sheet worker script <input type="text" name="attr_health_max" value="0"> <input type="text" name="attr_health_max_20_percent" value="0" readonly> <script type="text/worker"> on("sheet:opened change:health_max", function() {   getAttrs(["health_max"], function(values) {     setAttrs({       "health_max_20_percent": Math.floor((parseInt(values["health_max"],10) || 0) / 5)     });   }); }); </script>

Rebekah V. said: Is there any way to make it work it out 20% max health automatically using HTML This is the straight html way. <input type="text" name="attr_health_max" value="" /> <input type="text" name="attr_health_max_20_percent" value="@{health_max} * 0.2" disabled="true"/>