I think all of us have had to share out dates and times with someone over email regarding setting up an appointment, phone call, etc.
There are a few solutions out there that are fee or account type based.
I had no idea the Mircosoft Outlook App has a feature that allows you to share your Outlook or Google Calendar appointment availability easily.
I made a quick video overviewing this feature.
Outlook for iOS: https://itunes.apple.com/us/app/microsoft-outlook/id951937596?mt=8
Outlook for Android: https://play.google.com/store/apps/details?id=com.microsoft.office.outlook&hl=en_US