Discount percentage checks: why simple maths still goes wrong
Discount percentages look simple, but dynamic catalogues, rounding, variants and stale comparison fields regularly create inconsistencies.
What you need to know
A percentage claim should logically follow from the prices shown to the shopper. Small rounding differences may be reasonable; material mismatches deserve review.
Variant products can make “up to 50% off” very different from one percentage for the entire item.
Where online stores get it wrong
Problems often occur when the current price changes but cached badges, feeds or theme calculations do not.
What you can do in practice
Calculate from the same current reference source. Test PDPs, collections, mobile layouts and feeds after bulk price changes.
How Merqivio helps
Merqivio scans public product pages without passwords or admin access. A one-off scan checks visible price claims; historical verification requires stored price history.
Directive 98/6/EC · European Commission guidance
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