Jira has a great and clear way of doing this when entering time estimates in the task estimate field, simply using 1 letter after the weeks (w), days (d), hours (h) and minutes (m).
By not allowing a user to enter decimals, visualizing and reading the data is much easier.
For example, if a user adds 1,50h would they mean 1 hour and 50 minutes or 1 hour and 30 minutes? Jira solves this cleverly by chopping it up in the various units directly.
Examples of what can be entered:
- 1w 4d 1h 30m
- 4d 1h 30m
- 1h 30m
You can specify a time unit after a time value 'X', such as Xw, Xd, Xh
or Xm, to represent weeks (w), days (d), hours (h) and minutes (m),
From Jiras logging work and time tracking guides
This may differ with each organisation depending on how they set it but its a good, clear example of this.