Although this is contractual business, I wanted to make sure any UPS members here on this site see this so I am posting this alone. There is even a calculator in this post so please check it out.
Sometime in June, UPS Teamsters expect to be paid for nine months of retroactive pay for contractual raises. We recommend that you check to make sure you’re getting what you are due, using this calculator.

Your retro check covers pay from August 1, 2018 until April 29, 2019.

To calculate your raise, enter your old pay rate, your new pay rate, your number of straight time hours worked in that nine-month period, and your number of overtime hours worked into our retro pay calculator to get your gross retro pay

You can access your pay stubs on UPSers.com to get your pay rate and hours for each pay period, then add up the hours. Your new pay rate should be on your latest paycheck, after the raise was implemented in early May.
How to Check Your UPS Retro Pay - Teamsters for a Democratic Union