How to Calculate Your Retirement Date with OneLedger: Projections, Scenarios & the 4% Rule

June 21, 2026 · Retirement · Projections · Financial Independence · OneLedger

Do you actually know when you can retire? Not the legal age set by the government — your real financial independence date, the day your capital generates enough passive income to cover your expenses without selling your time. That's a concrete question, and it deserves a concrete answer.

OneLedger is built precisely for this: its 10–20 year projections let you model your wealth trajectory, test scenarios, and measure the impact of every financial decision before you make it.

I. Your "Retirement Number": How Much Do You Need to Accumulate?

The first step is defining your target capital — the amount your wealth must reach for passive income to replace your salary. A widely used benchmark is the 4% rule, derived from the Trinity Study: by withdrawing 4% of your invested capital each year, your portfolio statistically survives 30 years of retirement without running out.

The calculation is straightforward: multiply your annual expenses by 25. If you estimate needing $40,000 per year to live comfortably, your target capital is $1,000,000.

That number can feel overwhelming from a distance. But spread over a 20-year projection with consistent saving and compound interest, it becomes achievable — provided you track it and adjust every year.

II. Projecting 10–20 Years: Compound Interest Made Visible

OneLedger's greatest strength is showing you visually the growth curve of your wealth over time. You don't need to master financial formulas: you enter your data, and the app automatically calculates year-by-year evolution adjusted for inflation.

What You Can Model

In OneLedger, you enter your current wealth (accounts, portfolios, real estate, outstanding loans) and set your assumptions: expected investment return, inflation rate, monthly savings amount. The app then projects the total value of your wealth for each year ahead.

This is where projection becomes a powerful decision tool: you can compare scenarios side by side and immediately see the impact of a change in financial behavior.

III. Testing Your Retirement Scenarios

The real value of a projection tool is the ability to answer questions like: "What happens if I increase my monthly savings by $200?" or "At what date can I stop working if markets return 5% instead of 7%?"

Scenario 1: Increasing Your Savings Rate

Going from $500 to $700 in monthly savings over 20 years can move your retirement date forward by several years. In OneLedger, that change takes a few seconds and the chart recalculates instantly. You see the concrete impact, not an abstract formula.

Scenario 2: Adjusting Your Target Date

Wanting to retire 3 years earlier means either saving more or accepting a slightly higher withdrawal rate. OneLedger lets you test both levers in parallel to find the balance that fits your actual situation.

Scenario 3: Stress-Testing a Market Downturn

What if your investment returns 3% instead of the expected 6% for five years? Modeling this pessimistic scenario prepares you mentally and helps you build a safety margin into your planning.

IV. Comparing Actual vs. Projected Each Year

A projection without follow-up is just a pretty curve. What makes OneLedger different is the ability to update your actual balances each year and compare them to the planned trajectory. You immediately see whether you're ahead, on track, or need to adjust.

This annual process — entering real figures, measuring the gap, adjusting the plan — is at the heart of serious wealth management. And it happens entirely on your device, no cloud, no subscription, no one else with access to your data.

V. Why Do This Locally, on iPhone or iPad?

Your retirement date, your capital, your return assumptions — this is deeply personal information. Entrusting it to a cloud service that aggregates your data to profile you commercially is a trade-off many rightly refuse.

OneLedger takes a local-first approach: all data stays on your iPhone, iPad or Mac. Encrypted backups are under your control. No external server knows your financial situation. You plan your retirement in complete privacy.

VI. Where to Start

Here's a simple sequence to launch your first retirement projection in OneLedger:

1. Estimate your future annual expenses: the amount you need each year to live comfortably in retirement.
2. Calculate your target capital: multiply that amount by 25 (4% rule).
3. Enter your current wealth in OneLedger: accounts, portfolios, real estate, loans.
4. Set your assumptions: monthly savings, expected return, inflation rate.
5. Run the 20-year projection: find the year your wealth crosses your target capital.
6. Test scenarios: adjust variables and measure the impact on your retirement date.

Retirement isn't a distant, uncertain event. It's a milestone you can plan, simulate, and track year after year — with the right tools.