Although performing validation of an analytical method is a widely accepted standard, assessing and comparing the overall analytical potential covering all validation criteria is not straightforward. To answer the expectations of analytical chemists, we propose a new tool that solves this problem in a simple and user-friendly way. The Red Analytical Performance Index (RAPI) presented in this article is inspired by the Red-Green-Blue assessment model, in which the red colour represents analytical criteria. A simple, open-source software (mostwiedzy.pl/rapi) is used to assess the given method in relation to the ten pre-defined criteria. The performance in particular criteria is scored (0, 2.5, 5.0, 7.5, or 10 points), with the sores mapped to colour intensity and saturation where 0 is white and 10 is dark red. A star-like pictogram is automatically created, and divided into fields related to the particular criteria, with the final, mean quantitative assessment score (0–100) in the middle. It thus shows similarities to the Blue Applicability Grade Index (BAGI) – a recently published “sister” tool dedicated to practical criteria represented by the blue colour. Therefore, RAPI and BAGI can support and supplement known greenness assessment metrics, providing key information about functional characteristics, crucial for the method application. The use of RAPI was demonstrated using examples of various analytical methods, which were assessed in parallel using BAGI and the greenness metrics showing the closest analogy. This provided a comprehensive picture of the varied methods’ characteristics. We believe that RAPI will prove to be an effective and useful support for analytical chemists in methods evaluation and comparison.