Two Scenarios. One Honest Comparison. See exactly how a 1‑3% return gap compounds over 30 years.

Two‑Scenario Investment Comparator

Enter assumptions for both scenarios. Everything updates instantly. Use the asset class benchmarks to anchor your expected returns to real long‑run data.

Reverse Calculator — What Do You Need to Save?

Set a target future value and we'll solve for the annual contribution required. Useful for retirement, college funds, or any goal with a known dollar target.

Asset Class Benchmarks (Long‑Run Nominal)

Approximate long‑run nominal averages, drawn from public index history (1928‑2024). Past performance is not a guarantee of future returns — use these as anchors, not forecasts.

The Complete Guide to Comparing Two Investment Scenarios: CAGR, Fee Drag, Asset Class Expectations & Real Returns

Most investors lose six figures over a lifetime not because they pick the wrong stock, but because they misunderstand four numbers: CAGR, fee drag, real return, and asset‑class expectations. This guide walks through each of them using the two‑scenario comparator above, so you can stop guessing and start running side‑by‑side projections that reflect how money actually grows.

1. What CAGR Really Means (and Why Average Return Lies)

CAGR — Compound Annual Growth Rate — is the single rate that, applied every year, would turn your starting balance into your ending balance. The formula is simple:

CAGR = (Ending Value / Beginning Value)^1/years − 1

Why does CAGR matter more than the simple "average return"? Because arithmetic averages dramatically overstate growth in volatile assets. Imagine a portfolio that returns +50% one year and −50% the next. The arithmetic average is 0%, but $10,000 becomes $15,000, then $7,500 — a CAGR of −13.4%. The comparator displays CAGR for both scenarios so you are comparing the smoothed compounded reality, not a misleading average.

When you compare Scenario A and Scenario B side by side, focus on three CAGR signals: the spread between them (anything over 1 percentage point compounds heavily), the absolute level (anything above 11% deserves skepticism for diversified portfolios), and the relationship to your benchmark asset class (see the table above).

2. Fee Drag: The Silent Six‑Figure Tax

Investment fees are the most under‑appreciated variable in long‑term wealth. They look small — 0.5%, 1%, sometimes 1.25% — but they compound against you in exactly the same way returns compound for you.

Consider a $10,000 initial investment plus $6,000 annual contributions over 30 years:

• 7.0% gross return, 0.05% expense ratio (index fund): ≈ $663,000
• 7.0% gross return, 0.75% expense ratio (typical active fund): ≈ $588,000
• 7.0% gross return, 1.25% expense ratio (advisor + fund): ≈ $541,000

That 1.20 percentage point swing in fees costs $122,000 — more than 18% of the index‑fund outcome — for the same gross performance. To use the comparator correctly, always enter the net rate (gross minus expense ratio minus advisory fee). If your advisor charges 1% and your funds average 0.4%, your input is your asset class benchmark minus 1.4%.

This is why the personal‑finance community is so insistent about index funds with sub‑0.10% expense ratios: the math is not ideological, it's arithmetic. Run the comparator with two scenarios identical except for fee level — the difference is your honest cost of advice.

3. Realistic Asset Class Expectations

The most common modeling error is using a return assumption that doesn't match the underlying asset class. Here is what long‑run history (1928–2024) and current forward‑looking capital market assumptions suggest:

US Large‑Cap Stocks (S&P 500)

Historical nominal CAGR ≈ 10.2%, real CAGR ≈ 7%. Forward‑looking 10‑year forecasts from Vanguard, BlackRock, and JP Morgan currently sit at 5%–7% nominal, reflecting elevated valuations. Use 7%–8% as a base case for long horizons (30+ years), and 5%–6% for shorter ones.

US Total Stock Market

Roughly 10% nominal historical, with slightly higher volatility than the S&P 500 because of small‑cap inclusion. Use the same forward assumptions as the S&P 500 plus a small‑cap premium of 0.5–1%.

International Developed Equities (MSCI EAFE)

Long‑run nominal ≈ 7.5%–8%, with currency volatility adding noise. Forward forecasts are actually higher than US equities right now (7%–8%) because international valuations are cheaper.

Emerging Markets

Highly cyclical, long‑run nominal ≈ 8%–9% with annual volatility north of 22%. Forward CMAs sit at 7%–9%. Treat as a satellite holding capped at 5%–10% of equity allocation.

60/40 Balanced Portfolio

Historical nominal ≈ 7.5%, volatility ≈ 9%. The classic moderate portfolio. Forward CMAs cluster at 6%–7%. Use 7% for planning unless you have a specific reason to deviate.

US Aggregate Bonds

Long‑run nominal ≈ 4.5%, with the worst year on record being −13% in 2022. Forward 10‑year is currently 4.5%–5% thanks to higher starting yields. Bonds are not a "growth" asset — they're a volatility dampener.

REITs (US)

Long‑run nominal ≈ 9% with equity‑like volatility. Useful diversifier, but correlations with equities have risen since 2008. Use 8% in the comparator for forward planning.

High‑Yield Savings & Money Market

Currently 4%–5% nominal but extremely rate‑sensitive. Over a 30‑year horizon, expect a long‑run average closer to 2%–3% nominal — barely covering inflation. Not a wealth‑building vehicle.

4. Nominal vs Real: The Inflation Adjustment Most People Skip

If you project a $1,000,000 portfolio in 30 years at 3% inflation, that million dollars actually buys what $412,000 buys today. Inflation is the silent erosion that makes nominal projections feel reassuring and real projections feel like a wake‑up call.

The comparator's inflation toggle subtracts your inflation assumption from each scenario's return rate. A 10% nominal return at 3% inflation displays as a 7% real return. Always plan retirement targets in real (today's) dollars, then use nominal returns to back into the future‑value number you'll actually see on your statement.

Default to 3% inflation for long‑run US planning. Use 4% if you expect retirement spending dominated by healthcare and services (which inflate faster than headline CPI).

5. Time Horizon: Why 10 Years vs 30 Years Changes Everything

Compounding is non‑linear. The first decade of investing is dominated by your contributions; the third decade is dominated by returns on returns. Run this experiment in the comparator:

• Scenario A: $10K initial, $6K/year for 30 years at 7% → ≈ $663K
• Scenario B: $10K initial, $6K/year for 20 years at 7% → ≈ $310K

Ten extra years more than doubles the outcome — even though you only contribute 50% more total dollars. This is why "start now" beats "start with more later" almost every time. The comparator makes this concrete: try a Scenario A that starts 5 years earlier with smaller contributions vs a Scenario B that starts later with larger ones.

6. Volatility, Sequence Risk, and Why Single‑Rate Projections Are Optimistic

Every projection in this comparator assumes a constant annual return. Reality is lumpier: the S&P 500's actual annual returns have ranged from −37% to +37%. Two specific risks the smooth projection hides:

Sequence‑of‑returns risk: A bad early decade hurts far more than a bad late decade because losses compound on a smaller base of contributions. If you retire into a bear market and start withdrawing, sequence risk can permanently impair the portfolio.

Path dependency: Two portfolios with identical 30‑year CAGR can have wildly different intermediate values. Use the comparator to plan, but stress‑test by running pessimistic scenarios — drop 2 percentage points off your base‑case rate and check whether the outcome is still acceptable. If it isn't, you're under‑saving.

7. Using the Reverse Calculator to Set Honest Goals

Most retirement advice starts with "save 15% of income." That's a heuristic, not a plan. The reverse calculator inverts the question: given your goal, return assumption, and time horizon, what contribution is mathematically required?

If you need $1.5M in 25 years at a 7% return with $20K already invested, the formula:

PMT = (Target − Initial × (1+r)ⁿ) × r / ((1+r)ⁿ − 1)

solves for an annual contribution of approximately $22,300, or about $1,860/month. If that exceeds your savings capacity you have exactly three levers: lengthen the time horizon, lower the target, or raise the assumed return (which usually means accepting more risk). The reverse calculator forces this trade‑off into the open.

8. A 5‑Step Workflow for Serious Comparison

1. Pick your asset allocation and look up its long‑run nominal return in the benchmark table above.
2. Subtract your total fee load (expense ratios + advisory fees) to get a net rate.
3. Enter Scenario A as your base case and Scenario B as a stress test (rate −2%, or fees +0.75%).
4. Toggle inflation to see real‑dollar outcomes — the numbers you'll actually spend.
5. Run the reverse calculator to confirm the contribution is feasible. If not, adjust horizon or target.

9. Key Takeaways

• CAGR, not arithmetic average, tells the truth about compound growth.
• A 1% fee compounds to roughly 22% of terminal wealth over 30 years — minimize ruthlessly.
• Use forward‑looking CMAs (5%–7% for equities, 4.5%–5% for bonds) for the next decade, historical averages for 30+ year horizons.
• Always plan in real dollars. Toggle inflation on every projection.
• Time in market beats timing the market — start now with whatever you can.
• Stress‑test with a pessimistic Scenario B before committing to a savings rate.

This guide is educational and does not constitute personalized financial advice. Past performance does not guarantee future results. Consult a fiduciary financial advisor for advice specific to your situation.

Frequently Asked Questions