Force Index

The force behind each move: how far the price moved, times how much volume moved it.

What it measures

Alexander Elder’s Force Index multiplies the change in close by the bar’s volume and smooths the result with an EMA. It is in price times volume, so compare it only with itself. Volume here is the volume the price feed reports for each bar. For forex, brokers usually report the number of price updates in the bar, not an amount traded, so read it as activity rather than money.

How traders read it

Traders read a cross of zero as a shift in control, and use it with a trend filter: in an uptrend, a dip below zero is a chance to buy.

Formula

force = (close − previous close) × volume
Force Index = EMA(force, periods)

Settings and output

Call: forceIndex(periods)

Setting	Chart default
`periods`: Periods	13

What you get: a number.

Warm-up: with forceIndex(13), it asks for 2 bars of history and a run-up of 13, and its first value came on bar 15 of the example data.

Chart

Force Index drawn by its own code on example prices

The prices are made up, hourly, and the same on every page, so the chart shows how the indicator behaves, not how a market behaved.

In an algorithm

function onIntervalClose() {
  if (OPEN_POSITIONS_COUNT === 0 && ema(50) < CLOSE && forceIndex(13) < 0) {
    openPosition("BUY", { quantity: 10000, stopLossPips: 25, takeProfitPips: 50 });
  }
}