--- title: "How Much Do Official Exchange Rates Disagree? We Measured 31 Central Banks for a Year" description: "Original research: the same EUR/USD 'official rate' differs by a median of 142 basis points a day across ~30 central banks — and 32 bp even among 12 majors. One year, 264 trading days, measured from the banks' own published tables." canonical: https://allratestoday.com/blog/how-much-do-official-exchange-rates-differ/ source: AllRatesToday (https://allratestoday.com/) — Markdown mirror of the page above; index of all pages at https://allratestoday.com/llms.txt generated: 2026-10-27T14:04:49.190Z --- Ask thirty central banks for the official EUR/USD rate on the same day and you will not get one answer. You will get thirty — and they are further apart than most people writing FX policies assume. We ingest the published rate tables of [122 central banks](https://allratestoday.com/central-bank-rates-api/institutions/) daily, which makes the question directly measurable, so we measured it: **every same-day EUR/USD rate implied by every bank's own published table, over 264 trading days from August 2025 to August 2026.** **Key findings** - The same-day official EUR/USD differed by a **median of 142 basis points (~1.4%)** between the lowest and highest of ~30 banks; the widest day hit **615 bp (~6%)**. - Even across **12 major banks** (ECB, Fed, BoE, BoC, RBA, RBNZ, BoJ, Riksbank, Norges, CNB, NBP, SARB), the daily spread was a **median 32 bp** — on a €10M position, that is ~€32,000 of pure methodology. - **ECB vs Fed: 16 bp apart on an average day**; 42 bp on a bad one; 131 bp at worst. - The driver is **timing, not quality**: the Fed and BoE fix ~1 hour apart and differ by only 6.4 bp on average — while the ECB, fixing 4–5 hours earlier, sits ~16 bp from both. Same-day spread of official EUR/USD rates, monthly median Basis points between lowest and highest bank, Aug '25 – Aug '26 *Source: the banks' own published tables, ingested daily · AllRatesToday central bank API.* ## Method, in one paragraph For each bank and each trading day we computed the EUR/USD rate implied by that bank's own published table: directly where the bank quotes the pair, otherwise as the cross via the bank's home currency (for example, Norges Bank's NOK-per-EUR divided by its NOK-per-USD). Where a bank publishes only buy/sell, we used the midpoint. Monthly and quarterly publishers (SNB, HMRC, US Treasury) were excluded — the study compares same-day snapshots. For each day with at least ten banks reporting, we took the cross-bank median as the reference and measured every bank's deviation from it in basis points (1 bp = 0.01%). 264 qualifying days, 31 banks. The underlying data is queryable by anyone through the [central bank rates API](https://allratestoday.com/central-bank-rates-api/). ## The headline: "the official rate" is a range, not a number The median low-to-high spread across all banks was **142 bp per day** — the 90th percentile was 251 bp, and the widest single day (8 April 2026) reached 615 bp, driven by banks whose euro fixings are thin local crosses rather than deep-market readings. Peru's central bank, whose published EUR rate reflects a market where euros barely trade against the sol, averaged 104 bp from the global median — perfectly official, and 1% away from what Frankfurt printed the same day. Restricting to twelve major, deep-market banks does not make the effect disappear: **median 32 bp, p90 59 bp, worst day 133 bp**. There is no configuration of "respectable" sources in which the same-day official EUR/USD is a single number. ## Timing explains most of it The cleanest evidence in the dataset: **the Fed and the Bank of England differ by just 6.4 bp on average** — their snapshots (noon New York, 16:00 London) are about an hour apart. The ECB, which fixes at ~14:10 CET, sits **15–16 bp from both** on an average day. Same market, same quality of institution — four extra hours of market movement between the photographs. Divergence between official rates is, to first order, a measure of how much EUR/USD moves between fixing times. | Pair of banks | Fixing gap | Mean same-day \|diff\| | p95 | Worst day | | --- | --- | --- | --- | --- | | Fed vs Bank of England | ~1 h | 6.4 bp | 16 bp | 30 bp | | ECB vs Bank of England | ~3 h | 15 bp | 36 bp | 131 bp | | ECB vs Fed | ~4–5 h | 16 bp | 42 bp | 131 bp | ## The tightest and widest banks Mean absolute deviation from the daily cross-bank median, over the year: ### Closest to global consensus | # | Bank | Mean \|dev\| | p95 | | --- | --- | --- | --- | | 1 | Central Bank of Türkiye | 4.8 | 14.5 | | 2 | South African Reserve Bank | 6.7 | 20.9 | | 3 | Hong Kong Monetary Authority | 6.9 | 17.9 | | 4 | Narodowy Bank Polski | 6.9 | 20.4 | | 5 | National Bank of Romania | 7.1 | 20.7 | | 6 | Bank of Israel | 7.6 | 21.4 | | 7 | Reserve Bank of India | 7.8 | 20.3 | | 8 | Bulgarian National Bank | 7.9 | 28.6 | | 9 | Central Bank of Azerbaijan | 7.9 | 22.2 | | 10 | Central Bank of Sri Lanka | 7.9 | 23.4 | ### Furthest from global consensus | Bank | Mean \|dev\| | p95 | | --- | --- | --- | | Central Reserve Bank of Peru | 103.9 | 230.5 | | Bank of Russia | 35.7 | 107.9 | | Central Bank of Bahrain | 34.4 | 191.3 | | Bank Indonesia | 26.1 | 67.7 | | National Bank of Ukraine | 21.1 | 59.4 | The wide end is not a list of bad institutions — it is a list of *thin local EUR markets* (Peru, Bahrain's EUR cross of a USD-pegged dinar), sanctioned or managed markets (Russia), and administratively set fixings. Their dollar rates cluster far more tightly; it is the euro leg, fixed against illiquid local trading, that drifts. Which is itself a finding: **how "official" a rate looks depends on which leg of it you audit.** ## What this means in practice **For contracts:** "at the official exchange rate" is ambiguous by ~1.4% a day across banks — real money at any size. Name the bank, the series, and the date convention. (Our guide to [choosing between ECB, Fed, and BoE rates](https://allratestoday.com/blog/ecb-vs-fed-vs-boe-exchange-rates/) covers how.) **For multinationals:** two subsidiaries can each use their impeccable local official rate and produce intercompany figures 32+ bp apart on an ordinary day. Eliminations that "never quite net" are often this, not an error. **For anyone comparing a rate to Google:** an official fixing from 14:10 CET is *supposed* to differ from a live quote at 21:00 — the difference is definitional, not a data problem. (More on that split in [official vs market rates](https://allratestoday.com/blog/official-exchange-rate-vs-market-rate/).) ## Cite or reproduce this study This analysis is reproducible end-to-end from published central bank data: every input rate is queryable via the [AllRatesToday central bank API](https://allratestoday.com/central-bank-rates-api/) (the latest tables are free), and each bank's product page documents its source and fixing time. If you reference these figures, please link to this page as the source; we plan to refresh the study annually. ## The data behind this study Official rates from [122 central banks](https://allratestoday.com/central-bank-rates-api/institutions/), as JSON — latest tables free, no credit card. [Get your free API key](https://allratestoday.com/register/) ## Related Articles - [ECB vs Fed vs BoE: which official rate should you use?](https://allratestoday.com/blog/ecb-vs-fed-vs-boe-exchange-rates/) - [Official vs market exchange rates](https://allratestoday.com/blog/official-exchange-rate-vs-market-rate/) - [7 best central bank exchange rate APIs in 2026](https://allratestoday.com/blog/best-central-bank-exchange-rate-api-2026/) - [All covered central banks — product page](https://allratestoday.com/central-bank-rates-api/)