GP Margin and MU are calculated Excl VAT (cost excl VAT vs selling price excl VAT). MU = Selling Price ÷ Cost Price (e.g. 2.50 MU means you sell at 2.5× cost). Colour cue is a rough guide only (margin: red <20%, amber 20–35%, green >35% · MU: red <1.3, amber 1.3–1.7, green >1.7) — set your own real thresholds for your product lines.