Try https://numbat.dev/ (https://github.com/sharkdp/numbat). It's my go-to for any engineering calculations. It can also run locally.

  >>> 4 weeks + 59*3 hours -> days
  4 week + 59 × 3 hour  day
      = 35.375 day    [Time]

  >>> 5V / 50ohm -> mA
    5 volt / 50 ohm  milliampere
        = 100 mA    [Current]

Full syntax: https://numbat.dev/doc/example-numbat_syntax.html