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Opening Range Bands — VWAP & bands, on the price chart.
What Opening Range Bands measures
The forming window contains every bar whose start falls before the session open plus N minutes, using the session boundary the application applies — 17:00 CT on CME futures, not midnight. The band is only drawn from the first bar after that window closes: while the range is still forming it is not yet known, and drawing it live would make a level that is meant to be fixed move on screen. A session in which no bar falls inside the window — typically because history was loaded mid-session — produces no band at all rather than a partial range. No session contaminates another: every session restarts from nothing.
The formula, as implemented
This is not how the indicator is usually defined elsewhere — it is what the shipped code computes, documented next to the implementation:
Opening Range Bands — high/low des N premières minutes de CHAQUE session (ancrage CME 17:00 CT via `splitSessions`), prolongés en bande jusqu'à la clôture de cette session, plus le MILIEU du range en basis. FENÊTRE : barres dont le bucket start est < open + N min (même règle que l'IB/OR de structure.ts). La bande n'est émise QU'À PARTIR de la première barre postérieure à la fenêtre : pendant la formation le range n'est pas encore connu, et le tracer « en direct » ferait bouger un niveau censé être figé. Session sans aucune barre dans la fenêtre (chargement en cours de séance) → aucune bande pour cette session : un range partiel serait un mensonge. Chaque session repart de zéro — aucune contamination d'une session à l'autre. Complémentaire de `opening-range` (structure.ts, shape `levels`) : voir la note de l'en-tête du fichier. Défaut N=30 min.
How to read it
- The band describes where the session's first N minutes traded. Price spending the rest of the session inside it describes a session that never left its opening area.
- A break of the upper or lower edge tells you the session has moved beyond the range it opened in. It does not tell you the move will continue.
- The midpoint is the arithmetic centre of the opening range, useful as a reference when price returns into the band after leaving it.
- The width of the band is a direct measure of how volatile the open was. A wide band after a news-heavy open and a narrow one after a quiet open are not comparable levels.
- Compare the band against the previous session's band: an opening range that sits entirely above or below yesterday's says the session started from a different area.
Parameters and defaults
Duration defaults to 30 minutes and accepts 1 to 480. A shorter window produces a narrower, more quickly available band that is easier to break; a longer one captures more of the open and produces a range that is crossed less often. Color applies to the edges and the midpoint.
| Parameter | Type | Default | Range |
|---|---|---|---|
| Duration (min) | number | 30 | 1 – 480 |
What it does not show
The band only measures the opening window and says nothing about the rest of the session, however it develops. If your history begins after the session open, that session gets no band — by design, since a partial opening range would misrepresent itself. On sessions with very little early volume, a handful of trades can define a range that carries little meaning. Finally, the edges mark prices, not liquidity: whether a break matters depends on what is resting in the book and what trades through it.
Related indicators
- Session VWAP + σ bands — VWAP & bands
- Anchored VWAP (session open) — VWAP & bands
- Anchored VWAP — VWAP & bands
- Fibonacci Pivots — VWAP & bands
- Woodie Pivots — VWAP & bands
- DeMark Pivots — VWAP & bands
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Frequently asked questions
- What is the opening range on futures and when does it start?
- The opening range is the high and low traded during the first minutes of a session, here the first 30 by default. It starts at the session open the application uses, which on CME futures is 17:00 CT rather than midnight. The range is fixed once that window closes and is then extended across the remainder of the session.
- Why is there no opening range band on the current session?
- Two situations produce no band: the opening window has not finished yet, since the range is not known until it closes, or your loaded history starts after the session open so no bar falls inside the window. In the second case the band is deliberately omitted rather than computed from a partial range. Loading more history before the session open restores it.
- How long should the opening range window be?
- There is no correct duration; it depends on what you consider the opening phase for the instrument you trade. Thirty minutes is the default here and a common convention, while shorter windows produce tighter ranges and more frequent breaks. Whatever you choose, keep it consistent so that bands are comparable from session to session.