Bond Yield vs Inflation Calculator

A bond yield vs inflation calculator computes the real yield — the purchasing-power growth a bond actually delivers once inflation is accounted for. A 5% nominal yield with 3% inflation works out to a 1.94% real yield. When the real yield is negative (yield below inflation), the bond erodes purchasing power: you lose buying power even though it still pays interest. This is common during periods of financial repression.

Worked example: a 5% nominal yield with 3% expected inflation. Real yield = (1.05 / 1.03) − 1 = 1.94%. A quick approximation is 5% − 3% = 2%, close enough for a rough read. In money terms, 100k earning 5% is worth 105,000 in nominal terms after one year, but with 3% inflation its real purchasing-power value is about 101,940 — a small but positive real gain.

Reading the real yield: above 2% is a strong positive real yield (rare); 0-2% is a marginal positive real yield (typical); -2% to 0% is mild financial repression; below -2% is significant repression (seen in the 1970s and after large inflation spikes). Negative real yields tend to push investors toward riskier assets to preserve purchasing power. Inflation-linked government bonds, whose principal adjusts with inflation, are designed to hold real value when real yields on nominal bonds turn negative.

Run it with sensible defaults

Using nominal bond yield of 5%, expected inflation of 3%, the calculation works out to 1.94%. The defaults are meant as a starting point, not a recommendation.

The levers in this calculation

The two inputs — Nominal Bond Yield % and Expected Inflation % — pull in opposite directions. Real yield rises as the nominal yield rises and falls as expected inflation rises. Adjusting either shows how the two interact: at equal values the real yield is roughly zero, and the gap between them sets the result.

How the math works

Fisher equation: real yield = (1 + nominal)/(1 + inflation) - 1.

Why investors run this

A nominal yield on its own can be misleading when inflation is high: a headline 5% looks like growth, but if prices rise 7% the holding loses real value. Converting nominal to real yield puts bonds from different periods or economies on a comparable footing, which is the comparison that matters for purchasing power.

What this doesn't capture

The calculation assumes the nominal yield and inflation rate both hold steady over the period, and inflation is rarely that obliging. It does not model uncertainty in inflation expectations, credit or default risk, liquidity, or the effect of taxes on the interest received. The figure is a snapshot at the two rates entered, not a forecast.