P2P Index methodology
P2P Index publishes a market value per card and per grade. This page describes exactly how that figure is produced, what it includes, what it excludes, and when P2P Index chooses to publish nothing at all.
The five calculation rules
- Completed sales only — an unsold listing is an asking price, not a transaction.
- Robust median — outliers are trimmed before aggregation.
- Rolling window — recent market wins; old sales drop out of the calculation.
- Strict per-grade separation — raw, PSA, BGS, CGC and SGC are never aggregated.
- Reliability threshold — below a sufficient sample, no value is published.
What P2P Index does not do
P2P Index does not publish a 'recommended' price, does not weight its figures toward listings present on P2P Cards, and shows no estimated value on marketplace listings. The reference value and a seller's asking price are two distinct pieces of information, presented separately.
A reference value is not a resale guarantee. Actual condition, centring, current demand and trading region all move the final price.
Frequently asked questions
What is the value published by P2P Index based on?
On actually completed sales for a given card at a given grade, aggregated with a robust median over a rolling window. Unsold listings are never counted as sales: they appear separately, as asking prices.
Why a median rather than an average?
An average is skewed by a single outlier — a fire sale or a runaway auction. The median describes the price a normal trade closes at, which is the question a collector actually asks.
What does the displayed sample size mean?
It is the number of observed sales used in the calculation. Below a reliability threshold, P2P Index shows no value rather than publishing a fragile one.
Are grades mixed together?
Never. Each card + grade combination is computed and published separately. A PSA 10 and a raw copy are two distinct markets.
How often are values updated?
Values are recomputed daily. Every page shows the date it was last computed; no value is published without its date.
Is P2P Index free?
Yes. Consulting reference values is free and requires no account.