For those of you on linux, mac with bash, or WSL with bash I assembled a simple script to calculate time between dates similar to timeanddate.com's days calculator.

function datediff() {

d1=$(date -d "$1" +%s)

d2=$(date -d "$2" +%s)

sec=$(($d1 - d2))

sec=${sec#-}

echo $sec seconds

echo $((sec / 60)) minutes

echo $((sec / 60 / 60)) hours

echo $((sec / 60 / 60 / 24)) days

echo $((sec / 60 / 60 / 24 / 7)) weeks, $(( (sec / 60 / 60 / 24) % 7)) days

}

drop that in your .bashrc or a separate .sh file with #!/bin/bash at the top.

Usage:

$ datediff '3 Nov 2020' '1 Feb 2021'

7,776,000 seconds

129,600 minutes

2160 hours

90 days

12 weeks and 6 days