How do I calculate the breakeven inflation rate from nominal and TIPS yields?

Question

AcadiFi · Accepted Answer

**Breakeven inflation rate (BEI)** is the inflation rate at which an investor would be indifferent between a nominal Treasury and a comparable-maturity TIPS.

**Simple approximation:**
BEI ≈ Nominal yield − Real yield

**Exact formula (multiplicative):**
(1 + Nominal) = (1 + Real) × (1 + Expected Inflation) × (1 + Inflation Risk Premium − Liquidity Premium)

**Example — 10-year yields on April 7, 2026:**
- 10Y nominal Treasury: 4.25%
- 10Y TIPS real yield: 1.80%
- Approximate BEI: 4.25% − 1.80% = **2.45%**
- Exact: (1.0425 / 1.018) − 1 = 2.41%

**Interpretation:**
- If realized average inflation over 10 years exceeds 2.45%, TIPS outperform
- If realized inflation < 2.45%, nominal Treasuries outperform
- Small difference between approximate and exact (4 bps) — approximation usually sufficient

**What BEI really contains:**
BEI = Expected Inflation + Inflation Risk Premium − TIPS Liquidity Premium

So BEI is NOT a pure expectation — it includes a risk premium for holding nominal exposure AND a discount because TIPS are less liquid than nominal Treasuries.

**Adjustments by researchers:**
- Subtract ~15 bps for typical inflation risk premium
- Add ~10–25 bps for TIPS liquidity discount (can widen during stress to 100+ bps in 2008-09)
- Adjusted BEI ≈ 2.45% − 0.15% + 0.15% ≈ 2.45% (in normal times these roughly offset)

**Practical uses:**
1. Gauge market-implied inflation expectations
2. Compare across maturities to build inflation term structure
3. Identify regime shifts (BEI jumped from 1.5% to 3.2% during 2021–22)
4. Relative value — if survey expectations diverge from BEI, trade BEI pairs

How do I calculate the breakeven inflation rate from nominal and TIPS yields?

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