Percentages and rates

Conversion funnels, utilization dashboards, margins, and return tables all use percentages, but their storage conventions can differ. Choose the raw representation before adding a formatter. These examples use the plugin registration from Number setup.

1. Format a ratio as a percentage

The percent preset expects a ratio: 1 means 100%, and 0.125 means 12.5%.

grid.columns = [{
  prop: 'rate', name: 'Conversion rate',
  dataGridFormat: { value: {
    kind: 'preset', preset: 'percent',
    locale: 'en-US', decimalPlaces: 1,
  } },
}];
grid.source = [{ rate: 0.125 }, { rate: 1 }, { rate: -0.025 }];

The cells display 12.5%, 100.0%, and -2.5%. The percent scaling is part of international number formatting; it does not change the raw source.

Raw value	Display with one decimal	Meaning
0.125	12.5%	Ratio stored correctly
12.5	1,250.0%	Already multiplied by 100
0	0.0%	Observed zero
null	empty	Missing or unavailable

If your API sends 12.5 for 12.5%, normalize it once to 0.125 before populating the ratio column. Do not divide only in a display template while leaving calculations to assume the other convention.

2. Distinguish rate, change, and difference

Moving from 20% to 25% is a 5 percentage point increase and a 25% relative increase. Label them separately:

grid.columns = [
  {
    prop: 'relativeChange', name: 'Relative change',
    dataGridFormat: { value: {
      kind: 'preset', preset: 'percent', locale: 'en-US', decimalPlaces: 1,
    } },
  },
  {
    prop: 'pointChange', name: 'Change (pp)',
    dataGridFormat: { value: {
      kind: 'preset', preset: 'number', locale: 'en-US', decimalPlaces: 1,
    } },
  },
];
grid.source = [{ relativeChange: 0.25, pointChange: 5 }];

For rates quoted in basis points, store and label the unit explicitly: 25 bps means 0.25 percentage points, or a ratio of 0.0025. Use a plain number column named Change (bps) when the raw value is already basis points. There is no separate basis-point preset.

3. Choose aggregation and editing rules

• For BI conversion totals, calculate total conversions / total visits; averaging row percentages weights every row equally regardless of traffic.
• Relative growth requires a defined policy when the prior value is zero or missing. Keep an unavailable result as null rather than displaying an invented 0%.
• A ratio can exceed 1 or be negative in some metrics. Enforce 0..1 only when the domain requires that range, such as a completion fraction.
• Precision can hide small changes: 0.0004 displays 0.0% at one decimal. Increase decimalPlaces or use a basis-point column when the distinction matters.
• The numeric editor edits the raw ratio. A displayed 12.5% does not automatically make the editor accept 12.5 as 0.125. Document the input unit or provide an application-owned percent input adapter.

Change locale for localized percent placement and spacing; keep raw ratios identical across countries. See locale formats and currency and accounting for the companion money columns.