---
source: https://iinventedlight.com/library/notes/plain-honest-chart-scales.md
title: "Draw charts to scale with a zero baseline and forward time"
license: CC-BY-4.0
license_url: https://creativecommons.org/licenses/by/4.0/
source_license: "US government work, public domain; original synthesis in our own words"
license_family: usgov
attribution: "Summary by iinventedlight (AI-assisted). Sources: U.S. Securities and Exchange Commission, A Plain English Handbook, US government work, public domain; U.S. Web Design System (GSA), Data visualizations, US government work, public domain."
author: "iinventedlight (synthesis of cited sources); text drafted with AI assistance"
date: 2026-11-09
status: published
checked_on: 2026-11-09
as_of: 2026-11-09
confidence: medium
untested: "Editorial checklist only; not tested with readers. Sources fetched and evidence checked."
category: coverage-gaps
topic_area: "write-edit"
tags: [plain-language, charts, data-visualization, accuracy]
client: Librarian
sources:
  - id: S1
    title: "A Plain English Handbook"
    publisher: U.S. Securities and Exchange Commission
    url: https://www.sec.gov/pdf/handbook.pdf
    accessed: 2026-11-09
    license: "US government work, public domain"
  - id: S2
    title: "Data visualizations"
    publisher: U.S. Web Design System (GSA)
    url: https://designsystem.digital.gov/components/data-visualizations/
    accessed: 2026-11-09
    license: "US government work, public domain"
---
# Draw charts to scale with a zero baseline and forward time

**Answer:** Any graphic should be proportionately correct or drawn to scale. Avoid distortions that mislead the reader.

## SEC handbook

- Avoid graphics that start at a non-zero baseline; they distort differences by destroying correct proportions.
- Draw graphics to scale: a barrel isn't 50% bigger when production only went up 25%.
- When you group graphics side by side, avoid changing the scale from one to another; mixing billions, millions, then dollars can mislead the reader.
- Don't reverse time: in graphics showing information over time, time should flow forward.
- Trust your eye: if a graphic seems unclear or unhelpful to you, it probably is, whatever guidelines it follows.

## U.S. Web Design System

- Line chart origins should start at zero, unless clearly noted.
- Provide a textual representation of axis values and labels, and a tabular version of the underlying data.

## See also

- [plain-simple-charts](https://iinventedlight.com/library/notes/plain-simple-charts/)
- [plain-explain-numbers-do-the-math](https://iinventedlight.com/library/notes/plain-explain-numbers-do-the-math/)

## Claims

- id: C1
  claim: SEC: avoid non-zero baselines.
  source: S1
  evidence: "avoid graphics that start at a non-zero baseline"

- id: C2
  claim: SEC: time should flow forward.
  source: S1
  evidence: "time should flow forward, not backward."

- id: C3
  claim: SEC: keep scales consistent across grouped graphics.
  source: S1
  evidence: "avoid changing your scale from one graphic to another"

- id: C4
  claim: USWDS: line charts start at zero.
  source: S2
  evidence: "Line charts origin should start at zero, unless clearly noted."

## Sources

- [S1] A Plain English Handbook. U.S. Securities and Exchange Commission. https://www.sec.gov/pdf/handbook.pdf . License: US government work, public domain. Accessed 2026-11-09.

- [S2] Data visualizations. U.S. Web Design System (GSA). https://designsystem.digital.gov/components/data-visualizations/ . License: US government work, public domain. Accessed 2026-11-09.


License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted). Sources: US federal government works (GSA, GPO, SEC, CDC), public domain in the United States; third-party quotations inside those works were not used. Text was condensed and changed from the originals.

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Agents: [/agents.md](/agents.md) | [/.well-known/agent-library.json](/.well-known/agent-library.json).