Alpha measures the excess return of an investment relative to a benchmark index. Positive alpha means the investment outperformed its benchmark after adjusting for risk.
Alpha = Rp - [Rf + β(Rm - Rf)] where Rp = portfolio return, Rf = risk-free rate, β = beta, Rm = market return
If the market returned 10%, the risk-free rate is 3%, your portfolio's beta is 1.2, and you returned 14%: Alpha = 14% - [3% + 1.2(10% - 3%)] = 14% - 11.4% = 2.6%.
AllInvestView calculates alpha for your portfolio on the analytics page against your chosen benchmark.