*Semi* easy and very rough.

Look up your annual reported earnings on the social security website. Multiply each year's earnings by the "Index Factor" for that year you can get from plugging 2020 into this website.

https://www.ssa.gov/cgi-bin/awiFactors.cgiAdd them all up and divide by 35. (If you've worked for more than 35 years, only add up the 35 highest earning years).

If this number is < ~12,000, your annual social security payment would be 90% of this number.

If this number is between $12,000 and $72,000, your annual benefit is roughly equal to (your number - $12,000) * .32 + $10,800.

If this number is >$72,000 your annual benefit is roughly equal to (your number - $72,000) * .15 + $30,000

Obviously your actual benefit will be higher because it'll continue to be adjusted for inflation until you get close to retirement age but this gives you a sense of what your benefit worth in inflation adjusted dollars if you stopped working today and draw SS at full retirement age.

...Or you can put your numbers into this calculator and put in 0 for "amount you expect to earn in 2021"

https://www.ssa.gov/benefits/retirement/planner/AnypiaApplet.html