This sounds like a good solution to me. I can imagine some HN readers might comment 'ew Excel!' but it truly is the right tool for something where you have to t

This sounds like a good solution to me. I can imagine some HN readers might comment 'ew Excel!' but it truly is the right tool for something where you have to transparently demonstrate the logic to non-technical stakeholders in a way they can easily edit and adapt. Of course, you could build or buy a web app that handles this specific scenario more powerfully and scaleably, but if this is a quarterly problem rather than a everyday problem then the additional overhead of the different interface / logins may not be worthwhile. My only comments would be 1) macros are too hard for nontechnical users in my experience, even just w/r/t setup (excel prompts you a security warning to enable macros that is scary). I think you could maybe do this using the what-if analysis tables, simple ifelse formulas, and conditional formatting. 2) another improvement might be a cloud-based version where there is a link at which others can easily view + collaborate, like Google Sheets or Airtable. I think Excel is supposed to have this feature as part of the 365 subscription but I've never used it.