What makes a chart misleading if every number on it is correct? Usually it is the drawing, not the data. A misleading chart takes true figures and encodes them so your eye reads a different size, order or relationship than the numbers support. The bar is too tall, the dates are shuffled, or two unrelated lines are scaled until they seem to move together.

This page is for anyone who builds or reads dashboards, slide decks and news graphics: analysts, marketers, product managers, researchers. It walks through the specific tricks, each tied to a real example you can look up, and gives you a check for each one.

The thing most people get wrong is the rule itself. "The axis must start at zero" is true for bar charts and often false for line charts. Treating it as universal makes you miss some deceptive charts and wrongly accuse honest ones.

Why the same numbers can tell two stories

Every chart turns a number into something visual: a length, a position, an angle, an order. The chart misleads when that visual property stops being proportional to the number, or when it implies a relationship the data does not have.

The clearest case is the bar chart. You judge a bar by its length measured from the baseline, the line it grows out of. As Nathan Yau of FlowingData put it, truncating the axis is something "you don't do with bar charts, because the visual cue is the length of a bar relative to the origin." Cut off the bottom of the bars and the remaining stubs no longer compare in the ratio the numbers do.

A line chart works differently. You read it by the position of points and the slope between them, so what matters is change over time rather than the total height above zero. That is why a bar chart perception paper by Correll, Bertini and Franconeri argues that bar charts need a zero baseline while line charts showing a trend can sometimes justify a non-zero one, depending on context.

Bar chart Line chart
What your eye reads (Correll et al., arXiv 1907.02035) Length of the bar from the baseline Position of points and slope between them
Zero baseline required? Yes. A cut baseline breaks the length ratio Not always. Depends on what change means for the data
When a non-zero baseline is fine (Junk Charts; Tableau, June 1, 2020) Effectively never for comparing amounts Values sit far from zero and change slowly, or small changes matter a lot, such as body temperature from 37°C to 38°C
Dated failure (FlowingData, Aug 2012; arXiv paper) Fox News 2012 tax-rate bars starting at 34% National Review's 2015 climate chart starting at 0°F, which flattened the trend
The check Find the baseline. If it is not zero, the bars are lying about size Ask whether the axis range makes a meaningful change visible or invisible

Seven tricks, and a real chart for each

1. The truncated bar axis: Fox News, 2012

In 2012 Fox News aired a bar chart titled "Top Tax Rate." It compared the Bush-era top income tax rate of 35% with the 39.6% rate that would return if the Bush tax cuts expired, according to FlowingData. The y-axis started at 34%, not zero.

The real difference was 4.6 percentage points, a ratio of about 1.13 to 1. On screen the second bar looked about six times taller than the first, by the arXiv paper's count; Tableau's account says "more than five times." The arithmetic below shows why both descriptions are close. Media Matters catalogued this chart, and others like it, in a piece the paper cites called "A History of Dishonest Fox Charts."

Measuring how much the 34% axis exaggerates

Compare what the bars show with what the numbers say. Each bar's visible height is its value minus the baseline.

Left bar, visible height (35% minus 34%)1 point
Right bar, visible height (39.6% minus 34%)5.6 points
Ratio your eye sees (5.6 ÷ 1)5.6 to 1
Ratio in the data (39.6 ÷ 35)1.13 to 1
Increase the chart shows (5.6 ÷ 1, minus 1)460%
Increase in the data (39.6 ÷ 35, minus 1)13%

The chart draws an increase about 35 times larger than the real one (460 ÷ 13). Any time the shown ratio and the real ratio differ by more than rounding, the encoding is distorted. With a zero baseline the two bars would be 35 and 39.6 units tall, and the eye would correctly read a modest rise.

2. Out-of-order categories: Georgia's COVID-19 chart, May 2020

On Sunday, May 10, 2020, the Georgia Department of Public Health posted a bar chart of new confirmed COVID-19 cases in the state's five hardest-hit counties, Route Fifty reported. The dates were not in calendar order. Bars were sorted by case count, so April 28 appeared before April 27. The counties also swapped left-to-right positions each day, with the highest always on the left.

Sorted that way, any set of numbers slopes downward. The chart showed a steady decline that the real, more volatile data did not. State Rep. Scott Holcomb raised it publicly and wrote to the governor's office. The governor's spokeswoman, Candace Broce, first said the sorting was meant "to show descending values to more easily demonstrate peak values and counties on those dates." A DPH spokeswoman told the Atlanta Journal-Constitution it was a sorting error. By May 18, 2020, the chart had been redrawn in chronological order with each county in a fixed position, and Broce said: "Our mission failed. We apologize. It is fixed."

What makes this case instructive is that sorting bars by value is normally good practice. Andrew Gelman's Columbia statistics blog used it on May 18, 2020 to make exactly that point: ranking by size helps when categories have no natural order, and destroys the trend when they do, as dates always do.

3. Recent data drawn as if it were final

The Georgia chart had a second problem. Case counts there could take about 14 days to be finalized because of testing and backdating lags, so the most recent days always looked low. Researchers at Georgia Tech argued in a May 15, 2020 Slate article that officials were confusing reporting lags with real declines. Part of the fix was shading recent data points as "preliminary." Any dashboard fed by data that fills in late, from sales bookings to sign-ups attributed after a trial, has the same trap at its right-hand edge.

4. Two axes that manufacture a relationship

A dual-axis chart puts two series on one plot, each with its own vertical scale. Because each scale can be stretched independently, the designer controls where the lines sit relative to each other. "The scales of dual axis charts are arbitrary and can therefore (deliberately) mislead readers," writes Lisa Charlotte Muth of Datawrapper.

Her example: plotted on separate non-zero axes, German and global GDP from 2004 appear to rise at similar rates. Put on a shared zero baseline, global GDP rose about 80% through 2014 and German GDP about 40%. A study she cites, Isenberg et al. (2011), found superimposed charts of this kind "performed poorly both in terms of accuracy and time"; it had 15 participants, so treat it as suggestive rather than settled.

The Federal Reserve Bank of St. Louis posted a military spending chart, using data from the Stockholm International Peace Research Institute, that gave the United States its own y-axis. Economist Matthew Yglesias called it, in a January 22, 2023 post on X, "One of the most cursed dual-axis charts you will see in your lifetime," as Flourish documents. Flourish's redraw on a single $0 to $1,000 billion scale showed a very different relative gap. Noah Smith flags a Financial Times dual-axis chart that made the Chinese renminbi's share of global reserves, about 3%, look close to the dollar's, about 60%.

The joke version is Tyler Vigen's chart of pool drownings against Nicolas Cage films, which Smith cites: two unrelated series, two truncated axes, and lines that track each other perfectly.

5. A baseline that hides a real change

Truncation exaggerates. Its opposite minimizes. In 2015 National Review tweeted a chart from the Power Line blog captioned "The only #climatechange chart you need to see," with a temperature axis starting at 0°F. The Correll paper notes that this compressed the warming trend until it was illegible. Zero was there, and the chart was still misleading, because zero degrees Fahrenheit is not a meaningful floor for a change of a few degrees.

6. Bars not drawn to scale

Sometimes there is no axis trick at all; the bars are simply the wrong heights. Kaiser Fung of Junk Charts checked a chart of the "best acquisitions of all time." Facebook-Instagram, at $175.5 billion, should have a bar about 10 times Disney-Marvel's $17.5 billion. It was drawn at under 9 times. His test is the one to copy: divide the two values, then measure the two bars, and compare.

7. A window or metric chosen for the story

The time range you show and the thing you measure can carry the whole claim. In October 2026 a chart titled "Daily Activity over 3 Months" spread after Ukrainian drone strikes damaged Russian Yandex data centers between October 7 and 11. It claimed AfD activity on X fell by up to 56%, implying more than 99% of pro-party Russian bots had vanished. Austrian fact-checkers Mimikama found the underlying drop, Cloudflare traffic falling to 0.4% of its two-week peak, measured web requests, not political accounts. A separate tally of 611 Polish-language posts on October 11 and 12 had no pre-attack baseline, so no decline could be calculated from it at all.

The Christy and Spencer climate chart, debunked in coverage dated January 20, 2026, set 73 warming models against satellite observations that looked flat. Critics pointed to a 2017 Journal of Climate study in which 5 of 6 corrected satellite datasets showed warming. The chart's form was ordinary; the dataset choice did the work.

What about 3D charts?

Tilting a pie or bar chart into 3D makes the slices or bars nearest the viewer look larger than those further back, and makes heights hard to read against the axis. None of the sources on this page documents a specific dated 3D example, so this page does not offer one. The check is the same as for any chart: if you cannot read a value off it, it is decoration.

It's incredibly important for the data to be as accurate as possible and to be presented in a manner that is not misleading.

Scott Holcomb
State Representative (D-Atlanta), Georgia House of Representatives

How to check any chart, in order

Run these steps on a chart you are about to publish or one someone has put in front of you. Each targets one of the tricks above. Most take seconds once you know what to look for.

  1. Name the chart type and what it encodes

    Bars and areas encode amount as length or size. Lines and dots encode position and change. You should see: a clear answer to "am I meant to compare totals or read a trend?" Everything after depends on it.

  2. Find the baseline

    Look at the bottom of the value axis. For a bar chart it must be zero. For a line chart a non-zero start can be fine, but note it. You should see: a zero on any bar chart. If you see 34%, as on the 2012 Fox chart, the bar lengths are meaningless.

  3. Compute the real ratio and compare it with the drawn one

    Take the largest and smallest values and divide. Then compare with the visible bar heights. You should see: the two ratios match. Junk Charts' acquisitions example failed here: about 10 times in the data, under 9 times on the page.

  4. Check the order of categories

    If the categories are dates, months, stages of a funnel or anything with a natural sequence, they must appear in that sequence. You should see: April 27 before April 28. Sorting by value is fine only for categories with no inherent order, such as regions or products.

  5. Check that positions and intervals are consistent

    Each category should stay in the same place across panels, as Georgia's counties did not, and the gaps between time points should be equal or clearly marked. You should see: the same county, product or team in the same slot every time.

  6. If there are two y-axes, redraw on one

    Index both series to the same starting point or put them on a shared zero scale. You should see: whether the apparent relationship survives. Datawrapper's GDP lines went from looking parallel to one rising twice as fast as the other.

  7. Look at the time window and the right-hand edge

    Ask why the chart starts and ends where it does, and whether the latest points are still filling in. You should see: either a full available range or a stated reason for cutting it, and recent incomplete data marked as preliminary.

  8. Ask what is actually being counted

    Read the axis label and source, not just the title. You should see: the measured thing matches the claim. A chart of web requests is not a chart of bot accounts, as the October 2026 AfD chart showed.

  • Bar chart starts at zero

    No exceptions for comparing amounts.

  • Drawn ratio matches the data ratio

    Divide two values, compare two bar heights.

  • Time runs left to right in order

    Never sort dates by value.

  • Every category keeps its position

    Same slot across days, panels and filters.

  • One y-axis, or a stated reason for two

    Redraw on a shared scale to test any implied link.

  • Line chart range neither inflates nor flattens a meaningful change

    A 0°F floor can hide a trend as surely as a 34% floor can invent one.

  • Window and incomplete recent data are explained

    Shade or label points that will still change.

  • The measured quantity is the one the title claims

    Check the axis label and source line.

The mistakes people make when they go looking for lies

Calling every non-zero axis dishonest. This is the overcorrection. Kaiser Fung reviewed a forest-area chart covering 1990 to 2023 and did not fault its non-zero y-axis, because the values are far from zero and change slowly; starting at zero would have drawn a flat line. Noah Smith's advice cuts both ways: "Don't just assume it starts at zero!" Recognise it by asking whether the chart is a bar or a line. Fix it by applying the zero rule to bars only.

Assuming a zero baseline proves honesty. The 2015 National Review climate chart started at 0°F and still hid the change it was supposedly showing. Recognise it when a line looks flat but the subject is one where small moves matter. Fix it by choosing a range that fits the size of change that is meaningful for that measure.

Applying a good habit to the wrong data. Georgia's spokeswoman defended sorting by value as a way to highlight peaks, and in most bar charts that instinct is right. Recognise it when the categories are time periods. Fix it by locking time-ordered categories into sequence before any sort is applied, and by fixing the position of each series.

Wasting the frame. The same forest-area tracker started its time axis at 1960 although the data begins in 1990, leaving about half the plot empty, with gridlines at awkward values such as 33.01. Nothing is falsified, but the data is squeezed into half the space and becomes harder to read. Fix it by fitting the axis to the data you have.

Mistaking a deliberate cut for cherry-picking. Not every trimmed window is a trick. In the same Junk Charts post, a reader's alternative chart covered 2000 to 2023, dropping the first ten years, and Fung judged it far more informative than the original. "Choices frequently involve trade-offs," he wrote. The test is whether the choice is visible and whether the conclusion would flip with the full range.

When the zero rule bends

Small changes with large consequences. Tableau's June 1, 2020 post on truncation uses human body temperature: a rise from 37°C to 38°C is medically significant but nearly invisible on an axis starting at zero. A line chart of temperature, conversion rate or interest rates can legitimately zoom in, provided the axis is labeled clearly.

Values far from zero that drift slowly. Global forest area, population, or a company's total headcount fall here. A zero baseline turns any trend into a flat line, which is its own distortion.

Comparing amounts. Whenever the reader is meant to compare totals, use bars from zero, even if a line chart of the same data could start elsewhere. The chart type follows the question, and the baseline follows the chart type.

Dual axes. None of the sources here describes a case where a dual-axis chart was the best option; Datawrapper's advice is to index the series or split them into side-by-side panels. If you keep two axes, state both scales prominently and do not let the crossing or tracking of lines carry a claim.

Charts of probability. Some bars and gauges show the chance of an outcome rather than an amount, and they get misread as amounts. A forecast giving one party an 85 percent chance is a different thing from an 85 percent vote share, whatever the baseline.

The size of the distortion, in figures

~6x vs 1.13x
Fox News tax bars, 2012
How much taller the second bar looked versus the real ratio, with the axis at 34% (FlowingData; Correll et al.)
8 days
Georgia DPH chart, 2020
From posting on May 10 to the redrawn, chronological version by May 18 (Route Fifty)
80% vs 40%
Global vs German GDP, 2004 to 2014
Growth that looked similar on dual axes, on a shared zero scale (Datawrapper)
0.4%
Cloudflare traffic, October 2026
Share of two-week peak behind a viral bot chart; it measured web requests, not accounts (Mimikama)

What these figures cannot tell you is how common each trick is. Tableau's post notes it does not have a verified figure for how often truncated axes appear in bad visualizations, and none of the other sources counts frequency either. What would settle it is a systematic audit of published charts by type, which these sources do not report.

The cost of a misleading chart is also not just reputational. Georgia's chart sat in public view for about a week during a period when people were judging whether case counts were falling, and the Atlanta Journal-Constitution reportedly called it the third data "error" from state officials in as many weeks.

Questions people ask about misleading charts

No. Bar charts must start at zero because you read them by length, a point FlowingData and the Correll, Bertini and Franconeri paper both make. Line charts can start elsewhere when the values sit far from zero or when small changes matter, as Tableau's body temperature example and Junk Charts' forest-area critique show.

The 2012 Fox News "Top Tax Rate" bar chart is among the most cited. Its axis began at 34%, so a rise from 35% to 39.6%, a ratio of about 1.13 to 1, was drawn with the second bar roughly five to six times taller. Academic papers and Tableau's own guidance use it as the textbook case.

Posted May 10, 2020, it sorted each day's bars by case count instead of by date, so April 28 came before April 27, and it reshuffled the five counties daily. The effect was a false impression of steady decline. It was redrawn in chronological order with fixed county positions by May 18, 2020.

Not always, but the two scales are set independently, so the designer controls whether the lines appear to move together. Datawrapper's GDP example and the St. Louis Fed military spending chart both looked very different once redrawn on a single scale. Redraw before you trust any relationship one implies.

Divide the values of two bars, then compare the ratio of their heights. If they differ by more than rounding, the chart is distorted. Kaiser Fung used this test to find a Facebook-Instagram bar that should have been about 10 times Disney-Marvel's but was drawn at under 9 times.