How do you calculate walk-away cost without anyone knowing?

Short answer: use the grants you already have, a leave date, and a competing package only if you have one. Add the unvested value that would forfeit on that date. Keep the work on a device you control. Nobody at the company needs to see that you ran the numbers.

The inputs are yours. The dates are the plan's. The result is a private remainder, not a filing and not a notice.

FAQ

How do you get the number without telling anyone? Read the grant and the plan. Price unvested units and option spread on the leave date you actually mean. Do that on a device you control. Looking at your own paperwork is not a public listing.

Do you need a competing package? No. Current grants and a leave date are enough to name the forfeited remainder. A competing package only matters if you want a comparison against new money.

What should a private summary share? Ranges, not grant-by-grant dollars, if you send anything at all. Exact figures belong on the device that already has them.

If you want that math to run in the browser, Worth Leaving is a private calculator. Product surface: How the calculator works.