Midpack
Give me a museum and I'll fill it. (Picasso) Give me a forum ...
I see people asking for these from time to time, and this one is better than most I've seen. While I can just plug into TT for modeling (and have), this calculator is easier IMO - it has every conceivable input and it shows you all the details e.g. AGI, taxable income, SS taxation, PI, MAGI, marginal bracket, etc. FWIW
https://www.aarp.org/money/taxes/1040_tax_calculator.html
https://www.aarp.org/money/taxes/1040_tax_calculator.html