TradingView and data suppliers cannot make available the complete historical tick data required to calculate Renko bricks with maximal precision readily available, therefore, compromises must be made, as is common on other trading platforms. Our Renko brick calculations on historical bars follow these rules:
a) The chart's timeframe determines the finest level of detail used to calculate Renko bricks. For example, if your Renko chart uses a 30-minute timeframe, Renko bricks will use the close or the OHLC of 30-minute bars to calculate the box size. The smaller the timeframe, the more accurate calculations will be.
Here are examples of two Renko charts with the same Renko parameters (Traditional, 3), but using different timeframes: 1-minute and 1-day. As you can see, the 1-minute chart shows more detailed bricks, than the 1-day chart:
b) The smaller the timeframe used on charts, the less historical data is available. In order to provide more depth for historical Renko charts, when no more historical data is available at the current chart's timeframe, higher timeframe information is used to calculate Renko bricks until the maximum number of bricks allowed on a chart is reached.
The selection of the higher timeframes is as follows:
Timeframe on Renko chart
The highest timeframe used for deep history
The border between the higher and lower timeframes used in calculation is not static; it gets shifted into the future over time, which may lead to bricks being recalculated.
c) Renko wicks represent price movement, beyond the Renko brick's levels. Specifically, when the movement is not large enough to create a new brick. Recall that only the close of the chart's timeframe bars is used in Renko calculations, so price movement during that bar is discarded. The wicks represent the discarded information.
During the realtime bars, projection bars are built using price information as it comes in. Projection bars can only become “real” closed Renko bricks when the bar at the chart's timeframe closes. Therefore, they can recalculate until that happens.
Please note that Renko bricks prices, being inherently synthetic because of their nature, they do not reflect market prices at any precise moment in time, as normal bars do. While Renko bricks may provide useful interpretation of price activity in discretionary trading, using them to backtest, where order fills must reflect actual market prices at a specific time, is not recommended. Backtesting orders filled at Renko chart prices will inevitably be inaccurate. You can read more on the subject here.