Compare Sims puts two or more saved simulations in one table, one row per simulation, so you can read the same figures down a column. It's the right tool for "should I retire one year earlier?" or "what if I shift this 401k contribution to a Roth?".

What's in the table

• Success rate and the chance you outlive your money, the same figure as the Proof page headline (how it works). A plan with a single cycle shows a dash there, as on the Proof page.
• Ending portfolio, spending, and taxes - the median across cycles in bold, with the lowest and highest beneath it, so you can compare the spread of outcomes, not just the headline number. Amounts are rounded to fit ($2.31M, $180K); hover a cell for the exact figures.
• Sorting - click any column heading to sort by it, highest first. Click again for lowest first. Dollar columns sort by their median.
• Year-by-year detail - the Open in Proof icon on a row opens that simulation on the Proof page, with its year-by-year and tax views. Useful for spotting bracket changes between two strategies.

Recommended workflow: clone and tweak

The cleanest way to set up a comparison is to start from a known baseline:

1. Open the simulation you want as your baseline.
2. Use the duplicate-sim button in the sidebar to create a copy.
3. Change exactly one thing in the copy like retirement year, account allocation, or a Roth conversion adjustment.
4. Open Compare Sims and load both. The diff isolates the single thing you changed.

Monte Carlo and Risk-Based Guardrails plans

These plans run in the background, the same way they do on the Proof page, with a progress bar and a Cancel button above the table. They run one at a time, so a second one waits on its row until the first finishes. A plan you already ran on the Proof page, with no changes since, loads right away from that result.

What's not diffable yet

A few surfaces remain single-sim only. Plan Diagnostics runs against the actively-selected simulation, not the comparison set, so use the Open in Proof shortcut on a row to inspect diagnostics for that specific sim. Detailed adjustment-by-adjustment diffs (a true structural input diff) are not surfaced here. For now, treat Compare Sims as an output-comparison tool and rely on the Inputs tabs for input diffing.