How the Survival Rate Calculator Works

This tool helps you answer one critical question: “How long will my money last?” Whether you're navigating a job change, planning a career break, or preparing for early retirement, this calculator helps you understand how your savings and investments will support your lifestyle over time.

What It Calculates

The calculator runs two parallel simulations:

• Cash-Only Projection: Based solely on your savings, income, and expenses. This shows how long you can live off your cash without touching investments.
• Investments-Included Projection: Includes both your savings and your investment portfolio, factoring in compound growth. This offers a more realistic long-term estimate.

Inputs You Provide

• Current Savings: How much cash you have available today.
• Monthly Income: Any recurring income (like part-time work, side hustles, or rental income).
• Monthly Expenses: Your total recurring monthly costs (housing, food, insurance, etc.).
• Investment Balance: The value of your investment portfolio (e.g., stocks, bonds).
• Expected Investment Growth: The annual return you expect your investments to generate, compounded monthly.

Behind the Scenes: The Math

The calculator simulates your financial future one month at a time, up to 100 years (1,200 months). Here's what it does each month:

1. Calculate your monthly deficit or surplus: Subtract monthly expenses from income.
2. Simulate investment growth: Investment returns are added monthly using the formula:
   monthlyGrowth = investmentBalance × ((1 + annualRate)1/12 - 1)
3. Deduct the monthly shortfall: If income isn’t enough to cover expenses, the deficit is paid first from savings, then from investments.
4. Update balances: Both cash and investment balances are updated each month to reflect the new financial state.
5. Check for break-even: If your monthly investment growth becomes large enough to cover your deficit, the calculator records that as your break-even month.
6. Stop if you run out of money: If both savings and investments are depleted, the simulation ends.

Results You Get

• Time Until Zero (Cash Only): How many months your savings will last without investment returns.
• Time Until Zero (With Investments): How long your money lasts including compounding investment growth.
• Break-Even Month: If and when your investments generate enough monthly returns to cover your expenses indefinitely.
• Visual Chart: A side-by-side graph showing how your cash and investment balances change over time.

Scenario Testing Made Simple

Use the sliders to test “what-if” scenarios, like:

• What if your expenses increased by 20%?
• What if you reduced your income for a few years?
• How does your timeline change with a more conservative investment return?

Adjusting these sliders updates the simulation and chart in real time so you can explore the impact of lifestyle changes instantly.

Your Data Stays Local

All inputs and results are saved in your browser only (via localStorage). Nothing is sent to any server, and no account is needed. You can safely refresh or close the tab and come back later without losing your data.

Who This Is For

• People planning for early retirement or financial independence (FIRE).
• Freelancers or contractors navigating variable income.
• Anyone preparing for a big life change and wondering how long their money will stretch.

The goal is simple: give you clarity, not complexity. By visualizing your runway, you can make better decisions with confidence.