Numeric data

Metrics help users reason about the health and performance of their system. Because performance is highly dynamic, users may need to check these values periodically. Whenever possible, we should make them easy to scan.

Exact Values

Occasionally, a user will need to know the exact value of a metric or reading. If small changes to a large value are relevant, show the full number. If the number would overflow the horizontal space, show a tooltip with the complete value. Use the locale-appropriate thousands separator when displaying large values.Exact values should be used only when necessary.

Approximate Values

Typically, users can reason about metrics without the full value. Large values can be difficult to parse and can be disruptive to visualizations (we need to reserve very large spaces to accommodate the potential for very long numbers at runtime). Most of the time we’ll use the following simple rules to produce a compact presentation of a number:

• Always display 1-3 digits
• If the number is larger than 999, divide by an appropriate multiple of 1000 (or 1024, depending on unit) to arrive at a displayable number less than 1000.
• If you have divided the number, modify the unit to represent the converted SI unit. If the value is a count, set the unit to the symbol for the appropriate SI prefix (k, M, G, etc)

Units

For standard, well-recognized units, append the unit abbreviation directly to the value where possible. For unusual units, show a tooltip with the full unit name. For rates, show the item being counted as a field or column label and show the duration of the count as the unit.

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