Endowment Withdrawal Planner

Yale smoothing · Guard rail zones

Portfolio
Your total invested balance today.
Default is 4%. Change this to match your own plan — typically 3–5%.
Prior year withdrawal
Auto-saved each time you tap Record. Only fill in manually for your very first year, or to correct an entry.
Guard rail thresholds
Portfolio dropped this % from HWM — freeze at inflation-adjusted prior year amount.
Portfolio dropped this % from HWM — stop all withdrawals and use emergency funds.

This year's calculation
The highest portfolio value you have ever recorded. Update this if your portfolio has reached a new all-time high.
Optional. Enter the percentage your portfolio earned this year to see the dollar gain.

Tap Calculate to preview. Tap Record to save to history, carry the withdrawal forward, and lock in the high water mark.

Withdrawal history

No withdrawals recorded yet.

How to use this app

Getting started

1
Go to Settings and enter your portfolio value and withdrawal rate. The default is 4% — change it to match your own retirement plan. Tap Save settings.
2
Leave Prior year withdrawal blank for your very first year — the app seeds it automatically as portfolio × your rate.
3
Go to Calculate. Enter this year's portfolio value and high water mark. Tap Calculate to see the full breakdown.
4
Tap Record to lock in the number. This saves the withdrawal to History, carries it forward as next year's prior year automatically, and locks in the high water mark for the year. If your portfolio has reached a new all-time high, make sure the HWM field reflects that before you tap Record.
5
Each new year, go to Calculate, update the portfolio value and high water mark, and repeat.

The Yale smoothing formula

Your withdrawal blends two numbers to keep income steady through market swings:

70% × (last year's withdrawal × inflation factor)
+ 30% × (withdrawal rate × current portfolio)
= recommended withdrawal

The 70% side anchors income to last year so it stays stable. The 30% side adjusts with the market. The Calculate screen shows both sides so you can see exactly how the number was reached.

Guard rail zones

Green zone — portfolio within 20% of high water mark. Take the full Yale smoothed amount.
Yellow zone — portfolio dropped 20–30% from high water mark. Freeze at last year's amount × inflation only. No increase this year.
Red zone — portfolio dropped more than 30% from high water mark. Stop all portfolio withdrawals. Use emergency funds and let the portfolio recover.

High water mark

The highest portfolio value you have ever recorded. Update it whenever your portfolio reaches a new all-time high before tapping Record. The guard rail zones measure how far the portfolio has dropped from this peak — so keeping it accurate matters.

Emergency fund

The red zone assumes you have a separate emergency fund — typically 1–2 years of living expenses in cash or short-term bonds — that covers expenses during severe downturns without touching the investment portfolio.

Installing on iPhone

Open this page in Safari. Tap the Share button (the box with an arrow at the bottom of the screen), then tap Add to Home Screen. The app will appear on your home screen and open full-screen like a native app.

Data storage

All settings, prior year withdrawal, and history are saved automatically on this device. Nothing is sent anywhere. Your data will be there the next time you open the app.