How we calculate discount percentages

The exact formula behind every percentage on DealsChecked and why mismatches are rejected.

Every percentage on this site is computed, not copied. The formula is simple: (reference price − deal price) ÷ reference price, rounded to two decimals.

Why we recompute instead of trusting the feed

Source feeds occasionally carry a marketing percentage that does not match their own price fields. When our computed figure differs from the source figure by more than one percentage point, the offer is quarantined instead of published. You should never see a card where the math does not reconcile.

What the saving figure means

The dollar saving shown on every card is the difference between the two price fields at the last sync. It is the number we recommend deciding with — percentages flatter cheap items and understate savings on expensive ones.

What we cannot verify

We cannot verify that the reference price is what the item historically sold for. That is why deal pages carry an observed price history that grows over time, and why we never claim an all-time low we did not observe.