Is there a way to compare the previous day's volume on the first bar on 30min (or anyother intraday timeframe) chart to today's first bar? Thanks.

There are 390 minutes in a normal trading day for a stock. You can divide this by the number of minutes in the time frame (rounding any fractions up) to get the number of bars in that time frame.

So a 30 minute time frame has 13 bars. This means that if you want to check how much as a percentage the current 30 minute bar to the same 30 minute bar from the previous tradaing day, this would normally be the following (it could change if there is a market half day):

100 * (V / V13 - 1)

Note that this formula is only going to be the first trading bar of the day while the first bar is forming. Once the second bar starts forming, you would need to add 1 to all of the bars ago parameters.

100 * (V1 / V14 - 1)

You would keep need to add 1 more to the bars ago parameter throughout the trading day as new bars form.

Thanks Bruce.

You're welcome.