Currency Strength Monitor: Which Currencies Are Moving

Not exchange rates. Which currencies are actually strengthening, and by how much.

Every other currency Actor returns rates. A rate is a fact about a pair, and a pair tells you nothing about which side moved. EUR/USD falling could be a weak euro or a strong dollar, and those call for opposite decisions. This Actor answers that question directly: one row per currency, measured against the whole basket, ranked strongest to weakest.

What does this do?

It reads the European Central Bank's official daily reference rates, then derives what nobody else on the Store publishes:

#  cur   strength%    1d%     1m%    vol%   trend            best pair
 1  USD       0.669   0.131   1.887   5.16   strengthening 1  USD/JPY
 2  CHF       0.496   0.409  -0.943   4.26   strengthening 3  CHF/JPY
 3  AUD       0.422  -0.308   0.947   4.44   weakening 2      AUD/JPY
 4  NZD       0.134   0.044  -3.082   5.28   strengthening 2  NZD/JPY
 5  EUR      -0.088  -0.138  -0.459   2.00   weakening 2      EUR/JPY
 6  CAD      -0.351  -0.195  -0.635   2.93   weakening 2      CAD/JPY
 7  GBP      -0.354  -0.138  -0.605   3.00   weakening 1      GBP/JPY
 8  JPY      -0.918   0.198   3.015   8.11   strengthening 2  JPY/GBP

One read of that table tells you the week was about yen weakness — every other currency's best pair is against the yen — and that the yen is also the most volatile thing in the basket at 8.11% annualised. No amount of staring at EUR/USD gives you that.

Who is it for?

• Traders — a strength meter as data rather than a web widget, so it can drive a screen or a backtest
• Treasury and finance teams — annualised volatility per currency, which is the number that sizes a hedge
• Anyone holding several positions — the correlation matrix shows when two trades are really one bet
• Analysts and researchers — clean daily series from the central bank itself, no key, no scraping

What data do you get?

One row per currency:

Field	What it tells you
strengthRank, strengthPercent	Where it sits in the basket, and by how much it moved
change1DPercent … change1YPercent	One column per period you asked for
annualisedVolatilityPercent	Volatility from daily log returns, annualised over 252 trading days
trendDirection, consecutiveDays	Direction, and how many days it has run that way
bestPair, worstPair (+ their % change)	Where this currency gained and lost most
strongestCorrelation, weakestCorrelation	Its closest and most opposed partner
ratePerEur	The published ECB reference rate

The run summary carries the full correlation matrix. Switching on cross rates writes every pair in the basket to a second dataset.

How strength is calculated, and why it is done this way

A currency's value against the basket is the geometric mean of its cross rates, and strength is the change in that value over the period.

Geometric, not arithmetic, and that is not a detail. Averaging ratios arithmetically invents movement: a currency that halved against one and doubled against another would average (0.5 + 2.0) / 2 = 1.25 and appear 25% stronger having gone nowhere. The geometric mean gives exactly 1.

A worked example of why the basket matters. Suppose the dollar and the pound both rise 10% against the euro on the same day. A euro-denominated view reports the dollar down 9.09%. But the dollar did not move against the pound at all. Measured against the basket, the dollar is down 4.65% — the geometric average of a 9.09% fall and no change. That is the honest number, and it is the one in the table.

This also means the euro itself can be measured, even though every ECB rate is quoted against it. The euro is just another member of the basket.

Example: the majors, September 2026

Measured	Result
Currencies	8
Business days read	80, from 3 June to 22 September 2026
Run time	4.5 s, 52 MB
Failures	none

A useful check on the arithmetic: strength is relative, so the scores should very nearly cancel. In the run above they sum to +0.01.

What it refuses to do

• No signals. No buy, sell, or "strong buy". These are measurements of what has already happened, and nothing here forecasts.
• No intraday data, and none implied. See below.
• No invented precision. A currency with fewer than three usable observations gets null volatility rather than a number, and a single day's move is reported as a run of one, never as a trend.

A limit worth knowing

The ECB publishes one rate per currency per business day, at about 16:00 CET. So:

• This is daily analysis, not a live feed. If you need ticks, this is the wrong tool and the README says so before you spend anything.
• No weekend data. Weekends and TARGET holidays are absent, which is why periods are counted in trading days: a month is 22 observations, not 30 calendar days.
• Only dates where every currency in the basket has a rate are used, because a basket value from a partial basket is a different measurement. One thinly published currency therefore limits the whole set, and the run summary says how many days survived.
• Every rate is quoted against the euro, so cross rates are derived. The arithmetic is exact, but the euro is the measurement base even when it is not in your basket.
• One currency is deliberately not offered: the Bulgarian lev. Bulgaria adopted the euro on 1 January 2026, so the ECB's last lev reference rate is 31 December 2025. A series that has ended can never share a usable date with a live one, so including it could only ever fail a run. Every other currency listed was checked and was current.
• Strength is relative to the basket you chose. Change the basket and every score changes, because a currency is only ever strong compared to something.

Popular currency reports

Ready-made runs you can open and start, or copy as a starting point:

• Currency Strength Meter
• Daily Currency Strength
• Currency Volatility Ranking
• Currency Correlation Matrix
• US Dollar Strength
• Euro Strength
• British Pound Strength
• Japanese Yen Strength
• Commodity Currency Strength
• Emerging Market Currency Strength
• Asian Currency Strength
• Nordic Currency Strength
• Central European Currency Strength
• Currency Cross Rates
• One Year Currency Performance

Pricing

$0.01 per currency and $0.0005 per cross rate (only when cross rates are switched on).

The eight-currency run above costs $0.08, or about $0.11 with all 56 cross rates.

Input

Field	Meaning
Currencies	The basket, from the 31 the ECB publishes. At least two
Periods to measure	One change column each, in trading days
Rank strength over	Which period drives the score and ranking
Volatility window	Business days of returns for volatility and correlation
Include the correlation matrix	Adds the matrix and each currency's closest partner
Also output every cross rate	Writes all pairs to a second dataset

Integrations

Results export to JSON, CSV, Excel and Google Sheets, or go straight into a sheet, a dashboard or a model through the Apify API, webhooks, Make, Zapier and n8n.