Here's how to tell if a vintage pack is heavy: vintage Pokémon packs shipped with a real card, and real cards weigh more than the commons around them. This walks through weighing a sealed pack and checking it against confirmed holo pulls.
You'll need a scale accurate to at least 0.01 g — a jewelry or reloading scale, not a kitchen scale.
The set has to match exactly, since holo weights vary by print run.
The headline number, verdict, and histogram all update instantly.
The big number is how many confirmed holo pulls weighed less than yours; the sentence tells you where that lands, from "lighter than every confirmed holo" to "top of the range."
Every bar is a narrow weight band. Hover or tap a bar to see exactly how many confirmed holos landed there and at what weight.
The set and weight you entered are saved in the share link, so whoever opens it sees the same result you did.
Card stock, foil coverage, and print era all changed over the decades, so what counts as a heavy pack for Base Set Shadowless is a completely different number than for Skyridge or Aquapolis. That's why the set has to match exactly.
No — this shows how your weight compares to a database of packs already confirmed to contain a holo, not a certainty calculation. Weight is a strong signal collectors use, not a guarantee.