How Graded computes prices and populations
Every number on this site traces to a real transaction or an official census. This page documents the method, so you (or anyone citing us) can judge the data on its merits.
Prices: real sold comps only
Card values come from completed sales, primarily eBay sold listings and Fanatics Collect auction results. We never use asking prices, which typically run 20% to 50% above what buyers actually pay. A card's quoted value is the median of its recent sales at that grade, outlier-filtered so a single mislabeled or damaged-item sale cannot skew the number. Where a card trades thinly, we show the last verified sale and label it as such rather than modeling a number.
Populations: official census chains
Population counts (how many copies exist at each grade) come from grading-company census data via GemRate chains, refreshed monthly. When a card's chain cannot be resolved, we omit the population rather than show a zero. Monthly snapshots let us track grading velocity: how many new gems enter the census each month.
Grade-honest quoting
We quote each card in the grade that actually trades. A 1952 Topps Mantle is quoted in PSA 4 and a 1961 Fleer Wilt Chamberlain in PSA 8, because gem copies of true vintage are auction events, not markets. A PSA 10 price is never displayed below its own PSA 9; when the data shows that, it means a polluted comp, and we re-verify or show the 9 as the floor instead. Cards with no gem market are labeled honestly rather than given an invented PSA 10 price.
Coverage and freshness
As of July 2026 we track 990 unique cards across 104 live market indexes (every WOTC Pokémon set, One Piece, Dragon Ball, the major sports, and 21 athlete indexes), roughly 14,000 curated sales, and full population pyramids for the tracked WOTC and One Piece sets. Indexes rebuild monthly from per-card sale medians; the monthly market report documents each rebuild. Blog posts that embed live index data update automatically with each rebuild, and their dateModified reflects the last substantive refresh.
Where to use the data
The card value checker prices any card by grade. The market indexes show live per-set price tables and 12-month charts. The free pop report publishes exact PSA 10 populations without a login. The cert lookup verifies any slab.
Citing Graded
This data may be cited with attribution and a link to the relevant page on gradedworld.com. Numbers change with each monthly rebuild, so please include the as-of date shown on the page you cite.