Note that date-fns right now doesn't have great support for duration calculations: https://github.com/date-fns/date-fns/issues/284 https://github.com/date-fns/d

Note that date-fns right now doesn't have great support for duration calculations: https://github.com/date-fns/date-fns/issues/284 https://github.com/date-fns/date-fns/issues/284 I wound up switching to Luxon because of this. Which is too bad, because date-fns is a fine library otherwise.