Compound Growth & Savings Goal Calculator

Enter a starting balance, regular contribution, assumed return, fees, and inflation to project a nominal and inflation-adjusted balance — or flip it around and solve for the monthly contribution a target amount requires.

Before you enter numbers

Treat the return rate as an assumption, not a fact — model a conservative, base, and optimistic rate rather than trusting a single figure. Include any account or fund fee explicitly; it compounds against you the same way growth compounds for you.

Formula

FV = PV(1+r)^n + PMT × ((1+r)^n − 1) ÷ r

Worked example

$10,000 initial principal plus $500 monthly for 10 years, at a 7% assumed return, a 0.2% fee, and 2% inflation, produces nominal and real (inflation-adjusted) balances side by side.

Rule of 72 sanity check

Divide 72 by your assumed rate for a rough doubling-time estimate — useful as a quick cross-check against the full projection, most accurate for rates roughly in the 6–10% range.

Why time and fees matter more than the rate

A dollar contributed earlier compounds over more periods than the same dollar contributed later, which is why starting immediately tends to matter more than chasing a slightly higher assumed rate. Fees compound too, just against you — a 1% annual fee against a 7% assumed return effectively grows your balance at roughly 6% net, and the gap widens the longer the horizon.

Limits and privacy

This tool provides a general educational estimate, not individualized investment or retirement advice. No return, fee, or inflation figure is a guarantee, and the tool does not recommend any specific investment product.

The calculation runs in your browser. Do not put account numbers or other identifying information into a shareable link.

Related guide

Read How Compound Growth Actually Works for the Rule of 72 shortcut, why time matters more than rate, and how a 1% fee compounds against you over long horizons.

Frequently asked questions

Is the return guaranteed?

No — it’s always a modeling assumption; compare low, base, and high scenarios.

Why subtract fees separately?

Even a small annual fee compounds over long periods and can meaningfully shrink the ending balance versus a fee-free projection at the same nominal rate.

What is the real balance?

The nominal balance adjusted for your entered inflation assumption, approximating today’s purchasing power.

Can contributions grow each year?

Yes — set an annual contribution-growth rate if you plan to increase savings over time.

How is the required monthly contribution found?

The engine searches for the smallest monthly amount that reaches your target under the entered assumptions.

Nominal vs. real balance

The nominal balance is the raw dollar figure the projection produces; the real balance divides it by cumulative inflation to show approximate purchasing power in today’s terms. Compare any savings target set in today’s dollars against the real balance, not the nominal one.

Sources

• Investor.gov — Compound Interest Calculator, reviewed 2026-07-31
• U.S. Bureau of Labor Statistics — CPI Inflation Calculator, reviewed 2026-07-31