Constant currency is a way of restating a company's results as if exchange rates had not moved. A business that earns money in euros, yen or pounds but reports in US dollars translates those earnings into dollars every quarter. When the dollar weakens, the same amount of euro revenue becomes more dollars; when it strengthens, fewer. Constant currency removes that translation effect by applying the previous period's exchange rates to the current period's results. It exists because reported growth mixes two things: how much more business a company did, and what happened in currency markets.

The measure is not defined by US generally accepted accounting principles (GAAP) or International Financial Reporting Standards (IFRS). In the United States it is treated as a non-GAAP financial measure; in the European Union it falls under the rules for alternative performance measures. Each company chooses its own method.

How the calculation works

The standard approach takes current-period revenue in each local currency and translates it at the exchange rates of the comparison period, rather than the rates actually in effect. The result is compared with the prior period as reported. The gap between the reported and constant currency figures is the FX effect, short for foreign exchange.

A simple case shows the mechanics. Suppose a German advertiser spends €100 million with a US platform in two consecutive years, with no change in volume. If the euro averaged $1.08 in the first year and $1.16 in the second, reported revenue rises from $108 million to $116 million - growth of 7.4%. In constant currency, the second year is translated at $1.08, giving $108 million and growth of zero. The 7.4% was entirely currency.

Alphabet's first-quarter 2026 results, released on April 29, 2026, show how large the effect can be. Total revenue rose 22% to $109.9 billion. In constant currency, growth was 19%. The gap was concentrated in Europe, the Middle East and Africa (EMEA), where revenue of $31.5 billion grew 21% as reported but 12% in constant currency. Translated at prior-period rates, EMEA revenue would have been $29.0 billion, meaning $2.5 billion of the reported figure came from a weaker dollar. In the United States, where no translation occurs, the two growth rates were identical at 23%.

Hedging adds a second layer. Many multinationals use forward contracts and options to protect against currency swings, and gains or losses on those contracts can flow into revenue. Alphabet's definition, according to its earnings release, excludes "the effect of foreign exchange rate movements and hedging activities". In the first quarter of 2026, it set aside $180 million of hedging losses, against $260 million of gains a year earlier.

Methods diverge on several points:

  • Rate granularity. Meta translates current revenue "using the prior year's monthly exchange rates for our settlement or billing currencies other than the U.S. dollar", according to its third-quarter 2026 release. Microsoft, in releases going back at least to April 2015, uses "the average exchange rates from the comparative period".
  • Which currency. Meta applies rates to billing currencies - what advertisers pay in. Microsoft applies them to the currencies of entities reporting outside the US dollar.
  • Direction of restatement. Publicis Groupe works the other way. Its third-quarter 2026 release, dated October 13, 2026, restates the prior year at current rates: third-quarter 2025 net revenue of €3,529 million became €3,581 million at 2026 rates, a €52 million currency effect.

Who uses it in advertising

On the platform side, the major listed ad sellers report constant currency growth every quarter. Meta's third-quarter 2026 results, published October 21, 2026, showed revenue of $64.6 billion, up 26% on both a reported and constant currency basis. Currency was a slight drag: translated at 2025 rates, revenue would have been $64.7 billion, a $113 million difference. Over the first nine months of 2026, currency moved the other way, adding $2.3 billion to reported revenue.

Microsoft reports constant currency for nearly every line, including search advertising. For the quarter to March 2026, search revenue excluding traffic acquisition costs rose 12%, or 9% in constant currency. By the quarter to June 2026, the reported and constant currency figures had narrowed to 10% and 9%.

Criteo, which reports in dollars but is headquartered in Paris, said in February 2024 that fourth-quarter 2023 revenue was flat year on year but up 3% at constant currency.

On the buy side, the large agency holding companies fold constant currency into broader adjusted measures. WPP reports like-for-like growth, which it calculates by comparing "current year, constant currency actual results" with prior-year results adjusted for acquisitions and disposals. In the first quarter of 2026, WPP's revenue less pass-through costs fell 8.9% as reported and 6.7% like-for-like, according to its April 28, 2026 trading update. Publicis reports organic growth, defined as the change in net revenue "excluding the impact of acquisitions, disposals and currencies". Its third-quarter 2026 net revenue rose 7.9% as reported and 5.0% organically.

For marketers, the distinction changes how platform growth reads: 20% reported growth in a quarter of dollar weakness may mean slower growth in the markets where an advertiser buys. Currency also shapes guidance. Meta's forecast for the fourth quarter of 2026 assumes currency will be an approximately 1% headwind to year-on-year growth, while its April 2026 guidance for the second quarter assumed a roughly 2% tailwind.

Origin and evolution

No standard-setter introduced constant currency, and its first use in corporate reporting is not documented. Regulation followed the practice. The Securities and Exchange Commission (SEC) adopted Regulation G in January 2003, under the Sarbanes-Oxley Act, requiring companies that publish non-GAAP measures to present the most comparable GAAP figure and a reconciliation. Constant currency measures fall within that regime. The SEC's staff has pressed companies on method. In an October 31, 2017 comment letter to The Hackett Group, the staff noted that constant currency results "appear to be non-GAAP financial measures" and asked the company to "describe the process for calculating the currency effects, including which period's exchange rate is used". The staff revised its non-GAAP interpretations in May 2016 and December 2022.

In Europe, the European Securities and Markets Authority (ESMA) published guidelines on alternative performance measures on October 5, 2015, applying from July 3, 2016. They require issuers to define, reconcile and justify such measures.

Currency swings have repeatedly pushed the measure into headlines. On June 2, 2022, Microsoft cut its revenue guidance for the quarter to June 2022, attributing an expected $460 million reduction to unfavourable exchange rates as the dollar climbed. The reverse came in 2025: the US Dollar Index fell 10.8% in the first half of the year, its weakest first half since 1973, according to Yahoo Finance. That weakness is why Alphabet's and Meta's reported growth ran several points above constant currency in early 2026.

Limitations and disputes

The absence of a standard is the central weakness. Two companies can both report "constant currency growth" using different rate periods, currency bases and hedging treatments, so the figures are not directly comparable across firms.

Hyperinflation exposes the measure's limits. Translating Argentine peso revenue at last year's exchange rate produces enormous constant currency growth that reflects inflation rather than volume. MercadoLibre, which uses the label FX-neutral, states in its shareholder letters that its calculations "do not include any other macroeconomic effect such as local currency inflation effects". Its FX-neutral figures therefore still carry the effect of inflation in high-inflation markets.

Constant currency also treats local price changes as real growth. If a platform raises prices in a market to offset a falling local currency, the increase appears in constant currency figures as organic expansion, though it is partly a response to the currency.

The measure addresses translation only. Transaction exposure - costs incurred in one currency and revenue earned in another - still affects margins, and constant currency revenue says nothing about it.

Companies also choose which figure to highlight. The SEC's prominence rules exist because non-GAAP figures can overshadow the GAAP numbers they adjust.

  • Reported growth is the GAAP or IFRS figure, translated at actual rates. Constant currency is an adjustment to it, never a replacement.
  • Organic or like-for-like growth removes currency and also acquisitions and disposals. Constant currency removes only currency. Publicis and WPP report the broader measure; most US platforms report the narrower one.
  • FX-neutral is a synonym used by some companies, including MercadoLibre, for the same concept, though definitions vary.
  • Hedging is an actual financial transaction that reduces currency exposure. Constant currency is an analytical restatement that changes no cash flow. Some definitions exclude hedging effects; others leave them in.
  • Constant dollars, used in economics, adjusts for inflation rather than exchange rates, and should not be confused with constant currency.

Recent developments

Third-quarter 2026 earnings are under way. Meta reported on October 21, 2026, with reported and constant currency growth matching at 26% after nine months in which the weaker dollar had flattered reported figures. Alphabet's chief financial officer had signalled in July a slight foreign exchange headwind for the third quarter, after a one-point tailwind in the second, when Alphabet grew 24% as reported and 23% in constant currency. Publicis reported on October 13, 2026, with currency adding €52 million to third-quarter net revenue.

A further change is coming for IFRS reporters. IFRS 18, issued in April 2024 and effective for periods beginning on or after January 1, 2027, brings certain management-defined performance measures into the audited notes. The definition covers subtotals of income and expenses, and according to BDO, ratios such as growth rates fall outside it.

Timeline

  • January 2003 - SEC adopts Regulation G, requiring reconciliation of non-GAAP measures, including constant currency figures, to GAAP.
  • April 23, 2015 - Microsoft's quarterly release defines constant currency as results restated at comparative-period average exchange rates.
  • October 5, 2015 - ESMA publishes guidelines on alternative performance measures.
  • May 2016 - SEC staff update non-GAAP compliance and disclosure interpretations.
  • July 3, 2016 - ESMA guidelines take effect for EU listed issuers.
  • October 31, 2017 - SEC staff ask The Hackett Group to disclose which period's exchange rate it uses for constant currency.
  • June 2, 2022 - Microsoft cuts quarterly guidance, citing a $460 million currency hit from the strong dollar.
  • December 2022 - SEC staff issue revised non-GAAP interpretations.
  • February 2024 - Criteo reports fourth-quarter 2023 revenue flat as reported, up 3% at constant currency.
  • April 2024 - IASB issues IFRS 18.
  • July 1, 2025 - US Dollar Index records a 10.8% first-half fall, the steepest since 1973.
  • April 29, 2026 - Alphabet reports 22% reported and 19% constant currency growth; EMEA 21% versus 12%.
  • July 22, 2026 - Alphabet reports 24% reported and 23% constant currency growth.
  • October 13, 2026 - Publicis reports 7.9% reported and 5.0% organic net revenue growth for the third quarter.
  • October 21, 2026 - Meta reports 26% growth on both bases for the third quarter.
  • January 1, 2027 - IFRS 18 takes effect.

Summary

Who: Multinational companies that report in one currency but earn in many, including Alphabet, Meta, Microsoft, Criteo and agency groups such as WPP and Publicis. The SEC in the US and ESMA in the EU set disclosure rules for the measure.

What: A non-GAAP restatement of results at prior-period exchange rates, isolating business growth from currency translation. Methods vary on rate periods, currency bases and treatment of hedging.

When: A long-standing management convention with no documented origin, regulated in the US since Regulation G in 2003 and in the EU since ESMA's guidelines took effect on July 3, 2016. It drew attention during the strong dollar of 2022 and the weak dollar of 2025 to 2026.

Where: Quarterly earnings releases, trading updates, guidance and investor calls, usually alongside a reconciliation to reported figures.

Why: Reported growth combines volume and currency. Constant currency separates the two, letting investors and advertisers see how a platform or agency is performing in local markets, though the lack of a common method limits comparisons between companies.