I don't think there are calculators, per se, because it's more straightforward than that. You write up your withdrawal plan, based usually on tax efficiency, and then follow it.
Like, it might have something like: withdraw from taxable first, until depleted, doing Roth rollovers to make a ladder along the way, then withdraw from there, etc. etc.
If markets are down, you sell in order to rebalance--e.g. stick in line with your AA, so if your AA is 80/20 and markets have fallen so now you're 60/40, sell some bonds, etc.
Between your AA/IPS and your withdrawal order (just a simple list, basically), what is there to "calculate"?
Maybe you can describe more of what you mean, but I think it's just a straightforward "sell to keep in line with your AA, withdraw to minimize taxes".
It's a good question though, I'm sure there's stuff I haven't thought of. Following.