VWAP: Meaning, Formula and Session Reset

Define the observations before calculating

For individual transactions, VWAP equals the sum of price multiplied by quantity, divided by total quantity. A chart often substitutes one representative price for each bar, such as its high, low and close averaged together. That creates an approximation because the transactions inside a bar did not necessarily occur at that representative price. TradingView documents its bar-based calculation and reset settings.

Keep quantities comparable. Shares, futures contracts and a broker's quote-event counts measure different things. A calculation using FX tick volume weights observations by quote activity in that feed; it is not a consolidated record of all currency transactions worldwide. If the quantity sum is zero, the benchmark is undefined rather than a zero price.

An original three-observation example

Hypothetical transactions in one calculation interval

Price	Quantity	Price × quantity
100	10	1,000
102	30	3,060
101	20	2,020

The weighted total is 6,080 and the quantity total is 60, giving VWAP of 101.3333. The ordinary average of the three prices is 101. Volume weighting raises the result because the largest transaction occurred at 102. Neither result tells you the next transaction price.

Suppose another 40 units trade at 99. The cumulative totals become 10,040 and 100, so VWAP falls to 100.40. It does not fall directly to 99: the earlier observations remain part of the denominator. Later in a busy session, a small new trade may barely move the benchmark.

Resetting changes the question

A session VWAP starts again at the defined session boundary. A weekly setting accumulates a different population. Two charts can therefore disagree without either calculation being broken: one may include overnight futures trading while another starts with a selected daytime session. Record exchange, symbol, time zone, session template and whether extended hours are included before comparing values.

A fill compared against the entire day's VWAP also uses trading that happened after the fill. That can be a retrospective execution benchmark, but it cannot be information available to a decision made earlier. A strategy test must calculate only the observations available at that decision timestamp.

Use a benchmark without inventing a signal

Price above VWAP means price exceeds that specific historical weighted average. It does not establish that a security is expensive in a valuation sense, that every participant is profitable, or that a reversal is due. An average can lag a sustained price move, and the visible line contains no account-specific fee or stop information.

To reproduce a disagreement, export a small set of observations, keep the same starting time and compare cumulative numerators and denominators one row at a time. Then compare an event-anchored VWAP with a rolling VWMA. For execution analysis, the slippage calculator answers a different question: the cash difference between a stated reference and your actual fills.