Data Table Design

A table is not a spreadsheet dump. Every formatting choice either helps or hinders the reader's ability to compare, rank, and interpret values.

Alignment

• Right-align all numeric columns without exception — alignment makes magnitude visible at a glance
• Left-align text columns
• Center column headers only when the column is narrow and centering does not create visual disconnection from the values below
• Never mix alignments within a single column

Numeric precision

Consistency within a column matters more than absolute precision. Rules:

• Currency: two decimal places for unit prices; zero for large aggregates (1,240,000 not 1,240,000.00)
• Percentages: one decimal place unless the context is scientific
• Large numbers: use K, M, B suffixes with a note of the unit in the header rather than printing eight digits
• If a column mixes values at different scales (some in thousands, one in millions), flag the outlier with a footnote rather than changing the column format

Never imply false precision — round to the significant figures the data actually supports.

Sort order

Default to the sort order that answers the reader's most likely question:

• Rankings: descending by primary metric
• Time series: chronological
• Categories with no natural order: alphabetical or by a meaningful grouping variable
• Never present data in database row order unless that order is meaningful

Totals and subtotals

• Totals belong at the bottom of the column, not the top
• Use a visible separator (bold row, horizontal rule, or shaded background) above totals
• Averages and totals should not appear in the same row unless explicitly labeled — they are different statistics
• For percentage columns, a column total is rarely meaningful; show it only when the column sums to 100% by design

Column and row density

• Include only columns the reader needs to act on or compare. Every unnecessary column adds cognitive load.
• For tables wider than 8 columns, consider whether a chart or two smaller tables communicate better
• Freeze or repeat the label column when a table scrolls horizontally
• Alternate row shading (zebra striping) is acceptable for tables taller than 15 rows; avoid it for short tables

Headers

Every column header should name the metric and the unit. 'Revenue' is incomplete. 'Revenue (USD, thousands)' is correct. Avoid abbreviations unless they are universal in the reader's context.