I haven't closed any of my positions yet on Tradier (so I don't know how accurate the total account values are after completing a trade), but I did see that the total values up top are calculated with the option mid prices and the values of each leg are calculated on last prices. (As opposed to mid) Super confusing as the last prices are sometimes better or worse than mid. I asked Tradier about this and here is what they said:
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Hi,
You are exactly correct on which calculation is used in each section. The position page uses the last price while the total account value uses the mid-price. We do plan to use the mid for the position page at some point, but we do not have an ETA of when that will be changed.
Sincerely,
Chris Lepore
Director of Operations