People switch from Hotmail to Gmail for different reasons, regardless of purpose behind the switch, it is very easy to achieve that. Basically to transfer contacts from Hotmail to Gmail, you need to: 1) export contacts from Hotmail server to your computer; 2) import Hotmail contacts from computer to Gmail account.
You can refer to this guide: How to export and save Hotmail contacts to your computer?. Once you download a copy of your Hotmail contacts from Hotmail server to your computer, you can transfer them from computer to Gmail server following below steps. Also do not miss this guide: how to transfer contacts from Gmail to Hotmai?
How to Transfer Contacts from Hotmail to Gmail?
Log in your Gmail account from a web browser. Click on the Gmail from the top left corner, you will then see a drop down list with three items. See below screenshot.
Click Contacts to manage your Gmail contacts. Here you will find the list of all your existing email contacts.
Above your Gmail contacts list, there is a More option, click on it to expand the menu list like above. Then select the Import item from the menu list to import contacts from other mail service or sources to your Gmail account.
From above screenshot, you will know that you can import contacts to Gmail from CSV files from Outlook, Outlook Express, Yahoo mail, Hotmail, Eudora and other apps. To transfer contacts from Hotmail to Gmail, click the Choose file button to choose the Hotmail backup on your computer and then hit the Import button in blue to upload it to Gmail server.
You will be prompted to find and merge duplicate email contacts. Click the Find & merge duplicates link and follow the tips to proceed.
Congratulations! Now you have imported Hotmail contacts to Gmail account.