---
title: "G25 scaled vs unscaled coordinates: which to use, how to tell them apart"
description: "Every Global25 row exists in two forms, and mixing them is the hobby's most common silent error. What scaling does mathematically, which form each tool expects, and the tell-tale signs of a mixed comparison."
canonical: https://www.ancestrify.io/blog/g25-scaled-vs-unscaled
date: 2026-08-31T09:36:00+00:00
author: "Andi Thomaj"
---

# G25 scaled vs unscaled coordinates: which to use, how to tell them apart

When your [Global25 coordinates](/blog/what-are-global25-coordinates) arrive from the
[G25 Requests portal](/blog/g25requests-app-explained), you receive two files: a scaled row and
an unscaled row, same genome, same 25 axes, different numbers. Which one you paste matters more
than anything else you will do with them — a mixed comparison produces plausible-looking garbage
with no error message anywhere. This is the complete version of the scaled/unscaled story: what
the transformation is, which form to use where, and how to detect a mix-up after the fact.

## What scaling actually does

The 25 axes of the G25 space are principal components, ranked by how much variation each
explains: PC1 carries the most (the deepest continental structure), PC25 the least (fine regional
texture). In the **unscaled** form, each coordinate is the raw projection onto its axis — so PC1
values span a range several times wider than PC20's, and any distance computed across the raw row
is dominated by the first few dimensions.

The **scaled** form multiplies each dimension by a factor tied to that axis's share of variance,
rebalancing the row so the later, finer axes contribute meaningfully to distances. In effect:
unscaled geometry answers "how far apart are these genomes on the *broadest* axes"; scaled
geometry answers "how far apart are they across the *whole* structure, fine detail included".
For ancestry work within a continent — where all the action is in the fine axes — that is why
**scaled is the convention almost everywhere**: distance rankings, admixture fits, the published
reference averages, [Vahaduo sheets](/blog/vahaduo-g25-tutorial), and every panel in
[our tools](/lab/g25-distance) and the [paid analysis](/g25).

Unscaled rows are not junk — the raw projection has legitimate uses in some plotting and
methodological contexts — but in the consumer toolchain their practical role is: **the other
file, the one you keep labelled and do not paste.**

## The one unbreakable rule

Never let the two forms meet in one calculation. A scaled target against unscaled references (or
vice versa) computes fine, sorts fine, and means nothing: the mismatched row's early dimensions
are weighted entirely differently from the panel it is being measured against. The arithmetic
cannot notice — the numbers are numbers — so the failure is silent, and it poisons everything
downstream: distances, [fits](/blog/nmonte-explained),
[PCA positions](/blog/g25-pca-explained), averages.

Corollaries worth spelling out: keep both files exactly as delivered, filenames intact; never
"convert" one form to the other yourself with a factor found on a forum; and when you build a
[population average](/lab/average-g25), build it from rows of one form only — an average of mixed
rows is mixed garbage with extra steps.

## How to tell which row you are holding

Labels get lost. Three checks, in increasing rigour:

- **Eyeball the spread.** In an unscaled row, the first few values are conspicuously larger in
  magnitude than the rest; a scaled row's values are more even across the 25. Suggestive, not
  proof.
- **The absurd-distance tell.** Paste the row into a scaled-reference tool like the
  [distance calculator](/lab/g25-distance): a genuine scaled row of a modern person lands within
  ~0.02–0.05 of *some* modern population. If the nearest population on Earth sits beyond roughly
  0.08, you are almost certainly holding the unscaled form (or a corrupted paste) — suspect the
  row before suspecting your ancestry.
- **The fingerprint check.** The free [G25 authenticity check](/lab/g25-authenticity) reads a
  row's numeric signature and reports what it looks like — scaled, unscaled, rounded, edited or
  [simulated](/blog/what-are-global25-coordinates) — before you build anything on it.

## Answers to the questions people actually ask

**Which form does Ancestrify need?** Scaled, everywhere: in the free Lab tools and in
[Ancestry Map](/g25), our Global25 analysis, matching the convention of every reference panel we
publish against. Paste the file labelled scaled and you are done.

**Why do my percentages change between forms?** Because the geometry changed. An
[admixture solver](/lab/admixture) fitting unscaled rows is solving a different (broad-axis-dominated)
problem; neither result is "the real one" in the abstract, but the scaled fit is the one
comparable to every published model and calculator you will ever see.

**Both my forms give weird results.** Then the row itself is the suspect: thin input file,
transcription damage, or a simulated origin. Pre-flight the raw file with the
[file check](/lab/file-check) and the row with the [authenticity check](/lab/g25-authenticity);
the [full troubleshooting route](/blog/how-to-get-global25-coordinates) goes from there.

The two-file design is a small permanent tax the format charges for its
[portability](/blog/eurogenes-global25-history). Pay it once — label, verify, standardise on
scaled — and it never bothers you again.

Terms used here are defined in the [glossary](/glossary).