Fan Chart
Line chart with expanding confidence bands that shows forecast uncertainty.
Inflation Forecast
Central estimate with 50%, 80%, 95% confidence bands (lighter = wider interval)
View data (8 rows)
| Quarter | Forecast | Low 50 | High 50 | Low 80 | High 80 | Low 95 | High 95 |
|---|---|---|---|---|---|---|---|
| Q1 '25 | 2.10 | 1.95 | 2.25 | 1.85 | 2.35 | 1.75 | 2.45 |
| Q2 '25 | 2.30 | 2.05 | 2.55 | 1.85 | 2.75 | 1.65 | 2.95 |
| Q3 '25 | 2.50 | 2.15 | 2.85 | 1.85 | 3.15 | 1.55 | 3.55 |
| Q4 '25 | 2.40 | 1.95 | 2.85 | 1.55 | 3.25 | 1.15 | 3.65 |
| Q1 '26 | 2.60 | 2.05 | 3.15 | 1.55 | 3.65 | 1.05 | 4.25 |
| Q2 '26 | 2.80 | 2.10 | 3.50 | 1.50 | 4.10 | 0.8500 | 4.85 |
| Q3 '26 | 2.70 | 1.90 | 3.50 | 1.20 | 4.20 | 0.5500 | 4.95 |
| Q4 '26 | 2.90 | 2 | 3.80 | 1.20 | 4.60 | 0.3500 | 5.55 |
Use a fan chart when…
- Forecasts with uncertainty
- Showing prediction intervals
- Risk visualization
Avoid when…
- Historical data only
- When confidence levels are unknown
Data it needs
| Property | Value |
|---|---|
| Min Rows | 6 |
| Min Columns | 4 |
| Column Types | datenumbernumbernumber |
Visual anatomy
Guiding principles
- DesignChart-Question Fit
Shows 'when' combined with uncertainty
- IntegrityZero Baselines
Band width should grow with horizon — uncertainty compounds further into the future, so a flat band misrepresents the forecast
- ContextAbove All Else, Show the Data
Always label the band's confidence level (50%, 80%, 95%) directly on the chart; bands without a number are decoration, not data
Consider instead
Common mistakes
Not labeling confidence intervals
Bands too wide to be useful
History
Introduced by the Bank of England in 1996 for inflation forecasts.
Accessibility notes
Describe the central forecast trend, the labeled confidence level (e.g., '80% interval'), and how band width changes with horizon.
Related reading
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