How to Calculate Internal Rate of Return (IRR) with Example & Decision Rule
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Question:
A project has an initial cost of $1000 and generates the following cash flows over five years:
Year | Cash Flow ($) |
---|---|
1 | 200 |
2 | 300 |
3 | 300 |
4 | 400 |
5 | 500 |
Compute the Internal Rate of Return (IRR) for this project. If the opportunity cost of capital is 12%, should the project be accepted?
Explanation & Steps to Compute IRR
Step | Description |
---|---|
Step 1 | Assume K (discount rate) = 12% and compute the Net Present Value (NPV). |
Step 2 | If NPV < 0, the project is not financially viable at 12%. |
Step 3 | If NPV > 0, the project is viable, but we need to find the exact IRR by adjusting K until NPV ≈ 0. |
Step 4 | The discount rate at which NPV = 0 is the Internal Rate of Return (IRR). |
NPV Calculation at 12% Discount Rate
Year | Cash Flow (FV) | Discount Factor (1+K)^n | Present Value (PV) |
---|---|---|---|
1 | 200 | 1.12^1 = 1.12 | 178.57 |
2 | 300 | 1.12^2 = 1.2544 | 239.16 |
3 | 300 | 1.12^3 = 1.4049 | 213.53 |
4 | 400 | 1.12^4 = 1.5735 | 254.21 |
5 | 500 | 1.12^5 = 1.7623 | 283.71 |
Total PV of inflows | 1169.18 | ||
Initial Investment | 1000 | ||
NPV | +169.18 | Positive |
🔹 Since NPV > 0, the project is financially viable at 12%, but we need to determine the exact IRR.
Finding IRR (Where NPV = 0)
Year | Cash Flow (FV) | Discount Factor (1+K)^n (K = 17.7%) | Present Value (PV) |
---|---|---|---|
1 | 200 | 1.177 | 169.92 |
2 | 300 | 1.3853 | 216.56 |
3 | 300 | 1.6305 | 183.99 |
4 | 400 | 1.9191 | 208.43 |
5 | 500 | 2.2588 | 221.35 |
Total PV of inflows | 1000.25 | ||
Initial Investment | 1000 | ||
NPV | ≈ 0 |
🔹 IRR = 17.7%, since NPV becomes zero at this rate.
Decision Rule
Condition | Decision |
---|---|
IRR > Discount Rate (12%) | ✅ Accept the project |
IRR < Discount Rate (12%) | ❌ Reject the project |
Since IRR (17.7%) > Cost of Capital (12%), the project should be accepted.