Force Index: Reading the Force Behind a Price Move

The Force Index is an oscillator created by Dr. Alexander Elder that tries to answer a question most price-only indicators ignore: not just which way did price move, but how much conviction was behind that move. It does this by combining three pieces of information into one number — the direction of the price change, the size of that change, and the volume that traded while it happened. The result oscillates around a zero line, above it when buyers are in control and below it when sellers are, with the distance from zero reflecting how forceful the move was.

How the Force Index Is Calculated

The raw, single-bar Force Index is one of the more intuitive formulas in technical analysis:

Force Index (1) = Volume × (Current Close − Previous Close)

Read it piece by piece. (Current Close − Previous Close) is the price change from one bar to the next: positive on an up bar, negative on a down bar, and larger in magnitude the bigger the move. Multiplying by Volume scales that price change by how much actually traded. A large up-move on heavy volume produces a big positive number; the same up-move on thin volume produces a much smaller one. A move of the same size can therefore register as strong or weak depending entirely on the participation behind it.

That raw single-bar reading is far too jagged to trade directly, so the standard indicator smooths it with an exponential moving average — Elder's classic setting is a 13-period EMA of the raw Force Index. The smoothed line is what you actually watch. A short smoothing period (2 is Elder's own fast setting) reacts almost immediately and is used to time entries in the direction of a longer trend; the 13-period version is slower and better for reading the trend itself.

Reading the Zero Line: Direction and Strength

Everything the Force Index tells you is framed around its zero line, and it carries two separate pieces of information at once:

• Above zero — the volume-weighted price change is net positive: buyers pushed price up with enough participation to keep the smoothed line in positive territory. The further above zero, the more forceful the buying.
• Below zero — the volume-weighted price change is net negative: sellers are in control, and the further below zero, the more forceful the selling.
• Crossing zero — the moment the balance of force flips from one side to the other, which is the cleanest mechanical signal the indicator offers and the one this lesson's indicator alerts on.

Like MACD and unlike RSI, the Force Index has no fixed upper or lower bound. Its readings scale with the instrument's typical volume and price range, so a value of "50,000" means nothing in isolation — what matters is whether it's positive or negative, and how the current reading compares to that instrument's own recent history of peaks and troughs.

Entry Conditions

The custom indicator built for this lesson plots the 13-period Force Index in a separate window below price and fires an alert the instant it crosses zero:

• BUY — Force Index crosses from at or below zero to above zero, meaning force has just turned net-bullish.
• SELL — Force Index crosses from at or above zero to below zero, meaning force has just turned net-bearish.

The zero-line cross is the most mechanical way to use the indicator, but Force Index is arguably most powerful as a divergence tool. If price makes a new high but the Force Index makes a lower high, the new price high was reached on weaker force — a warning that the move may be running out of participation even though price itself hasn't turned yet. The same logic applies in reverse at lows. Divergence is a judgment call rather than a mechanical trigger, which is why this indicator alerts on the cleaner zero cross, but it's worth watching the peaks and troughs by eye once the indicator is on your chart.

Why Volume Changes the Picture

What separates the Force Index from a pure price oscillator like Momentum is the volume term, and it's worth understanding exactly what that changes. Two bars can close up by the identical number of pips, but if one did it on double the volume, its Force Index reading is double the size. The indicator is therefore skeptical of moves that happen on light participation and enthusiastic about moves backed by heavy trading — the idea being that a price move a lot of traders participated in is more likely to continue than one only a handful of traders drove.

There's an important caveat for forex specifically. Unlike stocks, the decentralized spot forex market has no single consolidated volume figure, so MetaTrader substitutes tick volume — the number of price updates in a bar — as a proxy for real traded volume. Tick volume correlates reasonably well with actual activity (busy periods generate more ticks), but it is not the same thing, and this is the same limitation discussed in the On-Balance Volume lesson. Treat the Force Index's volume component as a rough measure of participation, not a precise one.

Parameters

The indicator ships with a small set of adjustable inputs:

• ForcePeriod (default 13) — the EMA smoothing period applied to the raw Force Index. Elder's 13 is the standard for reading trend; drop it toward 2 for a fast entry-timing version, or raise it for a slower, smoother line that crosses zero less often.
• MAMethod (default EMA) — the type of moving average used for smoothing. EMA is Elder's original choice because it weights recent bars more heavily; SMA, SMMA, and LWMA are available if you prefer a different response.
• AppliedPrice (default Close) — the price the calculation reads on MetaTrader 4. On MetaTrader 5 the built-in function instead takes an applied volume type (tick or real), which the MT5 version of this indicator exposes.
• EnableAlert (default true) — pops up an on-screen MetaTrader alert the moment the Force Index crosses zero in either direction.
• EnablePush (default false) — sends the same cross notification to your phone via MetaTrader's push notification service.

Force Index vs OBV and MFI

The Force Index is one of three volume-aware indicators on this site, and knowing how they differ makes each easier to use correctly. On-Balance Volume adds or subtracts the entire bar's volume based only on whether the bar closed up or down — it ignores the size of the price change completely, treating a tiny up-bar and a huge up-bar identically. The Money Flow Index folds volume into a bounded 0-100 oscillator with fixed 80/20 zones, making it behave like a volume-weighted RSI. The Force Index sits between them: like OBV it's unbounded and can be read for divergence, but unlike OBV it scales its reading by the size of the price move, not just its direction. If you want a bounded overbought/oversold reading, reach for MFI; if you want a raw, unbounded measure of the force behind each move, the Force Index is the more direct tool.

A Word of Caution

Because the Force Index multiplies by volume, a single unusually high-volume bar — common around news releases or a session open — can spike the reading far out of proportion to what the price move alone would justify, and produce a zero-line cross that reverses a few bars later once volume normalizes. It also whipsaws in quiet, range-bound markets the same way any zero-line oscillator does: when price and volume are both flat, the smoothed line hovers near zero and crosses it repeatedly on noise. Treat a Force Index cross as more trustworthy when it agrees with a clear trend on the price chart itself, and be skeptical of it in a market that's visibly rotating inside a range — see Trend vs Range for how to tell the difference. As with every indicator on this site, this is educational content, not personalized financial advice — always combine it with your own read of price structure before acting on a signal.

Download the Indicator

This custom indicator calculates the Force Index and automatically alerts when it crosses its zero line. It's available for both MetaTrader 4 and MetaTrader 5 below.

How to Install — MetaTrader 4

1. Download the force-index-alert.mq4 file below.
2. Open MetaTrader 4 → click File → Open Data Folder.
3. Place the file in the MQL4/Indicators folder.
4. Restart MetaTrader 4, then drag the indicator from the Navigator window onto the chart.

How to Install — MetaTrader 5

1. Download the force-index-alert.mq5 file below.
2. Open MetaTrader 5 → click File → Open Data Folder.
3. Place the file in the MQL5/Indicators folder.
4. Restart MetaTrader 5, then drag the indicator from the Navigator window onto the chart.

Both files are source code — open and review the full code before using it, for your own safety.