Force Index Indicator: Formula, Settings and How to Read It
Force Index, defined by Alexander Elder in 1993, multiplies the change in close by the bar's volume and smooths the result with a 13-period exponential average. A single number then carries three properties of the bar: the direction of the move, its size, and the volume behind it.
Senzoukria · Indicators · Updated September 2026
Force Index ships with the Senzoukria desktop app, in the Volume group of the indicator catalogue. It is drawn in its own panel below the chart.
What Force Index measures
The raw term is the difference between consecutive closes multiplied by the current bar's volume; the first bar has no previous close and produces nothing. The exponential average is seeded with a simple average over the defined portion of that raw series, so the first plotted value appears at the period index. The sign follows the direction of the close change, while the magnitude grows with both the size of the move and the volume behind it — which is why an identical price move gives very different readings on a thin bar and a heavy one.
The formula, as implemented
This is not a description of how the indicator is usually defined elsewhere — it is what the shipped code computes, documented next to the implementation:
Force Index (Elder, 1993) : raw[i] = (close[i] − close[i−1]) × volume[i] FI = EMA_N(raw) (défaut N = 13) EMA à graine SMA sur le SUFFIXE défini de `raw` (raw[0] n'existe pas : pas de close précédent) — première valeur à l'indice N. POURQUOI : Elder combine les trois informations d'une barre — la DIRECTION (signe), l'AMPLITUDE (écart de close) et la PARTICIPATION (volume). Un mouvement large sur gros volume est une vraie force ; le même mouvement sur volume creux ne l'est pas. Le lissage EMA est ce qui rend la série lisible : le brut est trop bruité pour être tracé. Défaut N = 13 (Elder — sa version « moyen terme », celle qui sert aux divergences ; sa version courte N = 2 sert aux entrées, disponible via le paramètre). N = 1 rend le brut (EMA1 = identité), documenté et voulu. Warm-up → null.
How to read it
- The zero line separates bars whose closes advanced from bars whose closes declined, weighted by volume. A crossing marks a change in that balance, not a change of trend.
- Large positive spikes are wide moves on heavy volume; the same move on thin volume barely registers, and that contrast is the point of the indicator.
- At the 13-period default, divergence against price is the usual use: a higher price high with a lower Force Index peak means less volume-weighted push produced it.
- Elder's short version at period 2 is a different tool — it reacts almost bar by bar and is used for timing inside an already chosen direction rather than for divergences.
- Values scale with the instrument's volume, so compare readings only within the same chart.
Parameters and defaults
The EMA period defaults to 13, Elder's medium-term setting, on a scale that runs to 200. Period 2 reproduces his short-term variant. Period 1 returns the unsmoothed raw values, since a one-period exponential average is the identity — useful for inspecting individual bars, unreadable as a trend line. The default colour is teal (#26a69a).
| Parameter | Type | Default | Range |
|---|---|---|---|
| EMA period | number | 13 | 1 – 200 |
What it does not show
Force Index reads close-to-close change and total volume, so it has no access to the aggressor side and cannot separate buying that was absorbed from buying that moved price. It scales with the instrument's volume, which makes values incomparable between symbols and even between timeframes of the same symbol. Overnight gaps in futures are treated as a single close-to-close move attributed to one bar's volume, which can produce an outsized reading at the session open. Exponential smoothing lags by construction, and the 13-period default lags more than the 2-period variant.
Using it in Senzoukria
Add it from the Indicators panel of any footprint chart or candle chart. It runs on futures data from Rithmic or Databento and on crypto pairs from Binance and Bybit, on the same engine — the calculation does not change with the venue, only the data feeding it does. Market data subscriptions are billed by the provider, separately from the app.
Related indicators
- Volume — Volume
- Buy/Sell Volume — Volume
- Average Trade Size — Volume
- Volume ROC % — Volume
- Relative Volume — Volume
- Trade Count — Volume
See the full indicator library, or start with the order flow guide if you are new to reading aggression, delta and absorption.
Frequently asked questions
- What is the Force Index used for?
- It combines the direction of a bar's close change, its size, and its volume into one value, then smooths it. Traders use the smoothed series mainly to compare the volume-weighted push behind successive price swings, including cases where price makes a new extreme and the indicator does not.
- Should I use Force Index with a period of 2 or 13?
- Elder described both: 13 as the medium-term setting used for comparing swings, and 2 as a short-term setting that reacts nearly bar by bar. They answer different questions, and neither is a substitute for the other. The period is an ordinary parameter here, so either value is available.
- Does a high Force Index mean the move will continue?
- No. A high value states that a wide close-to-close move happened on heavy volume — a description of bars that have already printed. It carries no information about what follows, and heavy volume can equally mark a move being met by opposing size.