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Effective Duration Calculator.
Calculate effective duration from explicit bond price inputs.
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FAQs
How does the effective duration calculator work?
Enter the requested values to see a deterministic result. Assumptions are explicit and no live market or tax data is fetched.
Use Cases
Assess bond price volatility
Investors use effective duration to gauge how much a bond's price might change with interest rate movements, helping to manage portfolio risk.
Example: If a bond has an effective duration of 5, a 1% yield increase could lower its price by approximately 5%.
Compare bonds with embedded options
Effective duration allows investors to compare interest-rate sensitivity across bonds with different features, such as callable or putable bonds, on a like-for-like basis.
Example: Comparing a callable bond's effective duration to a non-callable bond's duration to see which is more rate-sensitive.
Frequently Asked Questions
- What is effective duration?
- Effective duration measures a bond's price sensitivity to interest rate changes, accounting for embedded options. It estimates the percentage change in price for a 1% change in yield, using the average of price changes from equal yield increases and decreases.
- How is effective duration calculated?
- Effective duration is calculated as (Price if yield decreases - Price if yield increases) / (2 * Initial price * Change in yield). This formula uses the bond's prices under equal yield changes to approximate the slope of the price-yield curve.
- Why use effective duration instead of modified duration?
- Effective duration is more accurate for bonds with embedded options (e.g., callable or putable bonds) because it incorporates the effect of potential cash flow changes. Modified duration assumes fixed cash flows, which may not hold for such bonds.
Tips & Common Mistakes
Tips
- Ensure the yield change (Δy) is expressed as a decimal (e.g., 0.01 for 1%) to get accurate results.
- Use consistent price units (e.g., dollars or percentage of par) for all inputs to avoid calculation errors.
- For bonds with embedded options, effective duration is more reliable than modified duration because it accounts for cash flow changes.
- Remember that effective duration is an estimate; actual price changes may differ due to convexity and other factors.
Common Mistakes to Avoid
- Using the same price for both yield increase and decrease scenarios, which results in a duration of zero.
- Forgetting to divide by the initial price, leading to a duration that is not a percentage change.
- Using a yield change that is too large, which can make the duration estimate less accurate due to convexity effects.
Last updated: August 13, 2026