# Calculate display and plot relative spread using Sierra Chart

I'm trying Sierra Chart for trading Bitcoin.

I would like to display relative spread for a given volume.

spread_rel = 200.0 * (ask - bid) / (bid + ask)

• where bid is bid price for a volume V
• and ask is ask price for a volume V

Ideally I would like to display it numerically and also to plot it

I ever saw Analysis / Studies / "Time and Sales Bid&Ask" but I think it's only for highest bid and lowest ask. Moreover it's an absolute difference... not a relative difference.

I first need to calculate bid and ask price for a given V volume using orderbook depth).

I also want to draw text on a chart. and also plot this spread_rel value.

it will help me a lot to understand how SC works.