Core Concepts

Three terms. One relationship. Understand these from first principles.

Concept 1 of 3
Nominal GDP

Nominal GDP

Output valued at TODAY'S prices — the raw, unfiltered number

  • ◆
    What it measures: Total market value of all final goods & services produced in a country during a period
  • ◆
    Priced at: Current-year prices — whatever things cost right now
  • ◆
    The problem: If prices doubled but output stayed identical, Nominal GDP doubles too — even though nothing extra was produced
  • ◆
    What it mixes: Real production changes AND price-level changes in a single number
  • ◆
    When it's useful: Comparing economic size at a single point in time, or computing the Deflator
MEMORY CUE

🧠 Nominal = Naive. It can't tell the difference between "we made more stuff" and "stuff just got more expensive."

The Core Formulas

One relationship. Four rearrangements. Know them all cold.

THE MASTER EQUATION
GDP Deflator = (Nominal GDP ÷ Real GDP) × 100
Everything else is algebra from this single equation.
▸ SOLVE FOR REAL GDP
Real GDP = (Nominal GDP ÷ Deflator) × 100
  • ◆
    When to use: You know current-price output and want to strip inflation out
  • ◆
    Deflator above 100: Prices rose — so Real will always be less than Nominal
  • ◆
    Example: Nominal=$15T, Deflator=125 → (15÷125)×100 = $12T
▸ SOLVE FOR NOMINAL GDP
Nominal GDP = (Real GDP × Deflator) ÷ 100
  • ◆
    When to use: You know real output and want current-price terms
  • ◆
    What's happening: Scaling real output up by today's price level
  • ◆
    Example: Real=$12T, Deflator=125 → (12×125)÷100 = $15T
▸ SOLVE FOR THE DEFLATOR
Deflator = (Nominal GDP ÷ Real GDP) × 100
  • ◆
    When to use: You have both GDP figures and need the price index
  • ◆
    Example: Nominal=$20T, Real=$16T → (20÷16)×100 = 125
▸ INFLATION RATE (using Deflator)
Inflation = ((D₂ − D₁) ÷ D₁) × 100
  • ◆
    D₁ = Earlier period deflator / D₂ = Later period deflator
  • ◆
    Same as: Any percent-change formula — applied to the deflator
  • ◆
    Example: D₁=108, D₂=116.6 → (8.6÷108)×100 ≈ 8%
KEY RULES — MEMORIZE THESE
Base year →Deflator = 100. Nominal = Real. Always. No exceptions.
Deflator > 100 →Prices higher than base year. Nominal > Real.
Deflator < 100 →Prices lower than base year. Real > Nominal. (Deflation)
Deflator basket →Updates annually to match what economy actually produces.
CPI basket →Fixed basket of consumer goods. Does NOT update annually.
Imports →CPI includes them. GDP Deflator does NOT (domestic only).

Formula Calculator

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THREE THINGS TO LOCK IN FOREVER
  • 1
    Deflator = (Nominal ÷ Real) × 100. Rearrange algebraically for any unknown.
  • 2
    Base year: Deflator is always exactly 100. Nominal always equals Real.
  • 3
    Real strips inflation. Deflator basket shifts. CPI basket is fixed. They diverge — know why.