Duration

Quick Definition

Duration measures how much a bond's price moves when interest rates change. It is expressed in years, and it tells you the approximate percentage price change for every 1 percentage point move in rates. A bond with a duration of 6 years will lose about 6% of its value if interest rates rise by 1 full percentage point, and gain about 6% if rates fall by 1 point.

What It Means

If you hold bonds, duration is the number that tells you how much pain you will feel when rates rise. Many investors think a 10-year Treasury bond is "safe" because the U.S. government will pay it back. The government will pay it back, but if you need to sell that bond before maturity and rates have risen, you will take a loss. Duration quantifies that loss before it happens.

The bond market has been living through a duration lesson since 2020. When the Federal Reserve raised rates from near-zero to over 5% in 2022, long-duration Treasury bonds lost 30% or more of their market value. Investors who understood duration saw it coming. Investors who did not were shocked that "safe" government bonds could fall that hard.

As of August 2026, the bond market remains under pressure. The 10-year Treasury yield sits at 4.71%, and the 30-year yield has climbed above 5.16%, the highest since 2007. The Fed has cut its federal funds rate to a target range of 3.5% to 3.75%, but long-term yields keep climbing because of fiscal deficits and capital demand from the AI infrastructure buildout. This divergence between short-term and long-term rates means duration risk is concentrated at the long end of the yield curve.

Duration matters because it lets you compare bonds and bond funds on a level playing field. A 2-year Treasury and a 30-year Treasury are both backed by the U.S. government, but they carry wildly different duration risk. The 2-year has a duration near 2, meaning a 1% rate hike costs you about 2% in price. The 30-year has a duration above 18, meaning the same 1% hike costs you about 18% in price. Same credit risk, completely different interest rate risk.

How It Works

There are two main types of duration that investors encounter: Macaulay duration and modified duration. You do not need to calculate Macaulay duration yourself, but understanding the distinction helps.

Macaulay Duration

Macaulay duration is the weighted average time until a bond's cash flows are received. It weighs each coupon payment and the final principal repayment by its present value, then divides by the bond's current price. The result is a number in years.

For a zero-coupon bond that pays nothing until maturity, Macaulay duration equals the bond's time to maturity. A 10-year zero-coupon bond has a Macaulay duration of exactly 10 years. For a bond that pays coupons, the duration is shorter than the maturity because you receive some cash before the end.

Modified Duration

Modified duration is the number investors actually use for risk management. It is derived from Macaulay duration and tells you the approximate percentage price change for a 1% change in yield.

The formula is:

Modified Duration = Macaulay Duration / (1 + Yield / payment frequency)

For most purposes, modified duration is close enough to Macaulay duration that the distinction does not change your investment decisions. When a bond fund reports a "duration of 6.2," that is almost always modified duration.

The Duration Rule of Thumb

For every 1 percentage point change in interest rates, a bond's price changes by approximately its duration in percentage, in the opposite direction.

This is an approximation. For large rate moves, the actual price change differs slightly because of a property called convexity, which we will cover below.

What Drives Duration

Three factors determine a bond's duration:

1. Time to maturity: Longer maturity means higher duration. A 30-year bond has far more rate sensitivity than a 2-year bond.
2. Coupon rate: Lower coupons mean higher duration. A zero-coupon bond has the highest duration for any given maturity because all cash comes at the end. A high-coupon bond has lower duration because you receive more cash sooner.
3. Yield level: Higher yields mean lower duration. When yields are high, distant cash flows are discounted more heavily, reducing their weight in the duration calculation.

Convexity: The Refinement

Duration is a linear approximation. In reality, the relationship between bond prices and yields is curved, not straight. This curvature is called convexity. For small rate changes, duration alone is accurate enough. For large moves, convexity matters.

Bonds with positive convexity (most non-callable bonds) gain slightly more when rates fall than they lose when rates rise. Callable bonds can have negative convexity, meaning they lose more when rates rise and gain less when rates fall, because the issuer can call the bond back when rates drop.

Real-World Examples

Example 1: The 2022 Bond Market Crash

In 2022, the Fed raised the federal funds rate from 0.25% to 4.25%, a 4 percentage point increase. Here is what happened to Treasury securities of different durations:

The pattern is clear. Duration predicted the damage. The 30-year bond, with a duration near 18, lost roughly 18% per percentage point of rate hikes. Four points of hikes times 18% equals about 72%, but convexity and the fact that the hikes were spread over a year reduced the actual loss to about 31%.

Example 2: Comparing Two Bond Funds in 2026

Consider two popular bond ETFs as of August 2026:

If rates rise another 1 percentage point, VGSH loses about 2.1% in price. TLT loses about 17.5%. If rates fall 1 point, VGSH gains about 2.1% and TLT gains about 17.5%. Same credit quality (U.S. government), completely different risk.

Example 3: A Bond Ladder Reducing Duration Risk

An investor building a bond ladder with bonds maturing in 1, 2, 3, 4, and 5 years creates a portfolio with an average duration of about 3 years. If rates rise 1%, the portfolio loses about 3% on paper, but the maturing bonds can be reinvested at higher rates. This is how duration management works in practice: you accept some short-term price risk in exchange for the ability to reinvest at higher yields.

Example 4: Dollar Duration in Practice

Portfolio managers often use dollar duration, which multiplies modified duration by the bond's price and the size of the position. If you hold $100,000 of a bond with a modified duration of 7, your dollar duration is $700,000. This means a 1% rate hike costs you about $7,000 in market value. Dollar duration lets managers aggregate rate risk across an entire portfolio and hedge it precisely using derivatives like Treasury futures.

Key Points to Remember

• Duration measures interest rate sensitivity, not credit risk. A Treasury bond and a corporate bond with the same duration have the same rate risk but different default risk.
• Longer maturity, lower coupons, and lower yields all increase duration.
• The duration rule of thumb: price change roughly equals negative duration times the rate change in percentage points.
• Bond funds report their average duration. Check it before buying. A fund with a duration of 15 is a rate bet, not a safe income investment.
• Duration works in both directions. Falling rates produce gains proportional to duration. The bond bull market from 1982 to 2020 made long-duration bonds look brilliant because rates fell for 38 years.
• Convexity refines the duration estimate for large rate moves. Most retail investors can ignore it, but portfolio managers cannot.
• Shortening duration is the primary defense against rising rates. Moving from long-term bonds to short-term bonds or cash reduces duration risk immediately.

Common Mistakes to Avoid

• Confusing duration with maturity: A 10-year bond does not necessarily have a duration of 10. A 10-year bond paying a 5% coupon has a duration closer to 7.5 years. Only zero-coupon bonds have duration equal to maturity.
• Ignoring duration when buying bond funds: Many investors buy "total bond market" funds thinking they are conservative. The Bloomberg U.S. Aggregate Bond Index has a duration around 6.2 as of mid-2026. That means a 1% rate hike costs about 6% in price. If you cannot tolerate that, you need a shorter-duration fund.
• Assuming high yield means high return: A long-duration bond fund yielding 5% can easily lose 15% in price if rates rise 2 points. The yield does not protect you from duration risk. You are earning 5% per year but losing 15% in principal.
• Forgetting that duration cuts both ways: Investors who sold long bonds in 2022 locked in losses. Those who held or bought more captured the full benefit when rates eventually stabilized. Duration is a risk metric, not a sell signal.
• Not checking duration after rate moves: Duration changes as yields change. When yields rise, duration falls (because distant cash flows are discounted more). A fund that had a duration of 7 at a 2% yield might have a duration of 6 at a 4.5% yield. Recheck periodically.

Related Concepts

Duration is inseparable from interest rate risk, which is the broader concept of losing money on bonds when rates rise. It applies directly to every bond and fixed-income security in your portfolio. The yield curve shows how duration risk varies across maturities, and the federal funds rate set by the Federal Reserve is the primary driver of short-term rate changes that ripple through all durations. For practical strategies on managing duration in retirement, read our guide on bond ladder retirement income. If you are deciding whether bonds belong in your portfolio at all, see bonds explained: do you need them. You can model how rate changes affect your overall returns using our investment return calculator. The SEC provides detailed information on bond duration and interest rate risk at SEC.gov.

Frequently Asked Questions

Q: What is a good duration for a bond portfolio? A: It depends on your goals and risk tolerance. If you need the money within 2 years, keep duration under 2. If you are saving for retirement in 20 years, a duration of 6 to 8 is reasonable. If you are retired and living off bond income, a shorter duration of 3 to 5 reduces the risk of having to sell bonds at a loss during a rate hike cycle.

Q: Does duration apply to bond funds the same way as individual bonds? A: Yes, but with a key difference. Individual bonds have a fixed maturity date, so if you hold to maturity, duration risk disappears and you get your principal back. Bond funds do not have a maturity date. They continuously buy and sell bonds, so the duration risk is permanent. A bond fund with a duration of 7 can lose 7% in a 1% rate hike and never recover that loss through price appreciation alone.

Q: What is the difference between duration and convexity? A: Duration is the first-derivative estimate of price sensitivity, a linear approximation. Convexity is the second-derivative adjustment that accounts for the curvature of the price-yield relationship. For rate moves under 1 percentage point, duration alone is accurate. For larger moves, convexity improves the estimate. Bonds with positive convexity perform slightly better than duration predicts during large rate swings.

Q: How do I find the duration of my bond fund? A: Check the fund's fact sheet or prospectus, usually available on the fund company's website. Look for "effective duration" or "modified duration." Morningstar and most brokerage platforms also display it. If you cannot find it, call the fund company. Never buy a bond fund without knowing its duration.

Q: Is a higher duration always riskier? A: Higher duration always means more interest rate risk, but it also means more upside if rates fall. If you believe rates will decline, long-duration bonds are the best way to profit. If you believe rates will rise or stay elevated, short-duration bonds or money market funds are safer. Duration is a tool for matching your rate exposure to your rate outlook, not a universal measure of badness.