How it works
The IRR calculator takes three inputs—what you invested, what it became, and how long you held it—and computes the constant annual growth rate that bridges those two points. This rate, expressed as a percentage, is what you'd need to earn every single year (compounded) to transform your initial investment into the final value.
Think of it as the "average annual performance" of your investment. Whether you held a stock for 3 years or a bond for 10 years, IRR lets you compare them on equal footing: which one grew faster per year?
The formula
IRR = (Final Value / Initial Investment)^(1 / Years) − 1
The calculator raises the ratio of final to initial value to the power of (1 divided by the number of years), then subtracts 1 to get the rate as a decimal. Multiply by 100 for a percentage.
Worked example
Suppose you invested $10,000 in a mutual fund on January 1, 2020. By January 1, 2024, it grew to $14,641. That's exactly 4 years.
Step 1: Divide final value by initial investment.
$14,641 ÷ $10,000 = 1.4641
Step 2: Raise to the power of (1 ÷ number of years).
1 ÷ 4 = 0.25
1.4641^0.25 = 1.10 (rounded)
Step 3: Subtract 1 and multiply by 100.
(1.10 − 1) × 100 = 10%
Your IRR is 10% per year. This means your investment compounded at 10% annually. To verify: $10,000 × 1.10 × 1.10 × 1.10 × 1.10 = $14,641. ✓
Real-world comparison
Imagine two investments:
- Investment A: $5,000 → $6,500 in 2 years
- Investment B: $5,000 → $8,000 in 4 years
Total returns look similar (30% vs 60%), but IRR reveals the truth:
- Investment A: IRR = 14.0% per year
- Investment B: IRR = 12.3% per year
Investment A actually outperformed, even though it gained less in absolute dollars, because it did it faster.
Common mistakes
Forgetting to include all fees and costs. If you paid $500 in transaction fees or taxes, subtract that from your final value before calculating. The calculator shows gross IRR based on the numbers you enter.
Mixing up holding period. Count only the years the money was actually invested. If you bought on March 15, 2020 and sold on March 15, 2023, that's exactly 3 years—not "2020, 2021, 2022, 2023" (which would be wrong).
Assuming IRR is guaranteed future performance. Past IRR is historical; it doesn't predict what your investment will earn next year. Use it to evaluate past results and compare options, not to forecast ahead.
Ignoring cash flows in between. This calculator works for a single lump-sum investment with no deposits or withdrawals during the holding period. If you added money midway, the IRR will be skewed. (For complex cash flows, use a modified IRR or consult a financial advisor.)
This calculator provides an estimate based on the values you enter. It is not financial, tax, or investment advice. Consult a qualified financial professional for decisions affecting your portfolio.