T-REX Score Calculator
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The T-REX Score: What It Is and Why Every Investor Should Know It
Most people who invest in mutual funds or ETFs have no idea how much money they’re actually losing to fees. Not because the information is hidden — it’s right there in the fine print — but because nobody really stops to do the math. The T-REX Score was built to do exactly that.
So, What Is the T-REX Score?
T-REX stands for True Return on EXpense. At its core, it answers one simple question: of every dollar your investment earns, how much do you actually get to keep?
The score runs from 0% to 100%. A score of 100% means fees took nothing. A score of 50% means half your gains quietly walked out the door in the form of charges, management fees, and other costs. Most investors, if they knew their T-REX Score, would probably be uncomfortable with what they found.
Why This Even Matters
Here’s something the financial industry doesn’t advertise loudly: a 1.5% annual fee sounds almost harmless. In reality, on a 10% gross return, you’re netting around 8.5% — and over 30 years, that gap compounds into a genuinely staggering difference in your final balance. We’re talking hundreds of thousands of dollars, depending on your starting amount.
The T-REX Score puts a single number to that gap. Instead of squinting at an expense ratio and trying to mentally calculate its long-term damage, the score just tells you directly what percentage of your return you’re keeping.
That matters for a few reasons:
- It lets you compare funds on an even footing, regardless of how they dress up their fee structures
- It forces transparency — a fund with strong gross returns but terrible fees will show a poor score
- It gives advisors a clear, honest way to talk to clients about costs
- It rewards low-cost investing strategies in a way that raw return figures don’t
The Formula (Simpler Than It Looks)
For a basic, single-period calculation:
T-REX Score = (Net Return ÷ Gross Return) × 100
So if a fund returned 9.5% before fees, and you netted 8% after expenses, your T-REX Score is:
8.0 ÷ 9.5 × 100 = 84.2%
For longer time horizons where compounding matters:
T-REX Score = [(1 + r_net)ⁿ − 1] ÷ [(1 + r_gross)ⁿ − 1] × 100
Where r_net is your annual return after fees, r_gross is before fees, and n is the number of years you’re invested. This version is more realistic for anyone thinking in decades rather than months.
What Goes Into the Calculation
Gross Return is straightforward — it’s everything the investment earned: capital gains, dividends, interest. Nothing deducted yet.
Fees are where it gets layered. The main ones to watch:
| Fee Type | What It Is | Typical Range |
|---|---|---|
| Expense Ratio | Annual fund operating cost | 0.03% – 2.50% |
| Management Fee | What the fund manager takes | 0.10% – 1.50% |
| 12b-1 Fee | Marketing and distribution | 0.25% – 1.00% |
| Sales Load | One-time entry/exit charge | 0% – 5.75% |
| Redemption Fee | Early withdrawal penalty | 0.25% – 2.00% |
| Performance Fee | Cut of gains above a benchmark | 15–20% of gains |
Add all of these up to get your total fee drag, then subtract from gross return to get your net return — the number that actually goes into your pocket.
Reading the Score
Once you have a number, here’s roughly how to interpret it:
| Score | What It Tells You | Commonly Seen In |
|---|---|---|
| 95–100% | Excellent efficiency | Passive index ETFs |
| 85–94% | Good | Low-cost active funds |
| 70–84% | Average | Standard mutual funds |
| 50–69% | Poor | High-fee products |
| Below 50% | Very poor | Hedge funds, expensive wrappers |
A Real-World Comparison
This is where the score becomes genuinely eye-opening. Take two funds with identical gross returns:
| Fund A | Fund B | |
|---|---|---|
| Starting Amount | $100,000 | $100,000 |
| Gross Return | 8.0% | 8.0% |
| Annual Fees | 0.10% | 1.50% |
| Net Return | 7.90% | 6.50% |
| Value After 30 Years | ~$987,000 | ~$661,000 |
| Total Fees Paid | ~$13,000 | ~$339,000 |
| T-REX Score | 98.75% | 81.25% |
Same market. Same strategy. A $326,000 difference — purely from fees.
What the T-REX Score Doesn’t Tell You
It’s worth being clear about the limits. The score doesn’t measure how skilled a fund manager is, doesn’t account for risk, and doesn’t factor in taxes. A fund with a high T-REX Score might still underperform a benchmark. A hedge fund with a 40% score might genuinely be worth it for certain institutional investors.
It also requires knowing your gross return, which isn’t always easy to find for certain fund types.
Think of it as one lens — a very useful one — rather than the complete picture.
How to Use This in Practice
If you want to put this to work:
- Pull the expense ratio and any other fees from your fund’s prospectus or fact sheet
- Find the gross return (some brokerages and platforms show this; otherwise estimate from net return plus fees)
- Run the formula — or use a calculator on platforms like Morningstar or Vanguard
- Compare your funds side by side on this basis, not just on headline performance
Small habit changes — moving from actively managed funds to index ETFs, avoiding sales loads, using tax-advantaged accounts — can meaningfully move your score upward over time.
The uncomfortable truth about investing fees is that they don’t feel painful in the moment. 0.5% here, 1% there — it all feels abstract. The T-REX Score makes it concrete. And once you see what those percentages translate to over a lifetime of investing, it’s hard to go back to ignoring them.