How to Use This Tool
Include shipping before indexing your basket against a like-for-like competitor. Shelf-price comparisons can call you expensive or cheap while customers see the opposite total at checkout.
Why Price Index needs more than a raw total
An index above 100 means your delivered basket costs more; it does not measure quality or assortment. For this page, the useful comparison is your delivered price index, not whichever input happens to be largest. The Price Index result answers the decision in the heading and should not be reused as a score for a different workflow.
The exact Price Index formula
Index equals your basket plus shipping divided by competitor basket plus shipping × 100. The visible fields are Your basket, Competitor basket, Your shipping and Competitor shipping. For Price Index, read each printed unit before entry and make the values describe one transaction, cohort or reporting window. If those scopes differ, the displayed your delivered price index may be arithmetically valid but operationally meaningless.
Interpreting your delivered price index
Investigate the products contributing most to the gap before applying an indiscriminate discount. The ten-percent comparison is deliberately narrow: it tests the influence of your basket and is neither a forecast nor a confidence interval. Preserve the values used, their dates and the resulting decision so a later reviewer can reproduce why Price Index supported the choice.
What this Price Index model leaves out
Taxes, memberships, coupons, availability and product-quality differences are excluded. That is where Price Index stops being trustworthy. If an excluded factor could reverse your delivered price index, extend the model explicitly or use the authoritative account system instead of hiding the factor inside an unexplained adjustment.
Evidence and independent verification
The reference reviewed for Price Index is FTC — Advertising and marketing basics. FTC — Advertising and marketing basics supports the named definition or rule but does not supply private values for your delivered price index. Before acting on the result, reconcile the worked example with the relevant dashboard, invoice, export or measurement.
Private, reproducible calculation
Price Index runs its arithmetic in the current browser tab and requests no login or API key. That keeps the Price Index inputs away from the site's calculation server, while leaving the user responsible for detecting stale data or a changed platform rule. When an assumption changes, reopen FTC — Advertising and marketing basics and rerun the saved Price Index scenario.
Sources & assumptions
Tool Spec v2 · verified 2026-08-20. Platform rules and fees can change; the editable inputs remain authoritative for your account.
Official references
- FTC — Advertising and marketing basics (checked 2026-08-20)
Model assumptions
- Every input covers the same reporting period or cohort.
- Taxes, memberships, coupons, availability and product-quality differences are excluded.
- The calculator uses only the visible fields and does not fetch account data.
