Dimensions

Dimensions are configurable analytical tags attached to every ledger transaction, replacing the proliferation of GL sub-accounts you find in older accounting systems. Common dimensions include Department, Cost Centre, Project, Region, Customer Group, Salesperson, and Brand. In Business Central, eight global dimensions are available with up to two shortcut dimensions reportable directly from the chart of accounts. In Dynamics 365 Finance the limit is higher (up to ten financial dimensions). Dimensions can be required, restricted to combinations, or defaulted from master records, and they make slice-and-dice reporting in Power BI or built-in account schedules straightforward.

In practice, the design decision that matters most is choosing which two dimensions become Business Central's shortcut dimensions — they get their own columns on every document line, making them fast to set and report on, while the remaining global dimensions need an extra click. Get the choice wrong (a rarely-used dimension as a shortcut, a constantly-reported one buried) and every user pays a small daily friction cost for it; changing shortcut dimensions after go-live is a genuine data-conversion project, not a setting flip, because they're baked into the posted-entry table structure.

Where confusion arises: dimensions are for categories worth filtering and totalling by, not for unique identifiers — a dimension value that's different on almost every transaction (a batch ID, say) generates a new internal dimension-set entry per transaction with almost no reuse, which bloats the underlying table and slows dimension-filtered reports without adding real analytical value. If a value already exists as its own field (a Location Code, for instance) and maps one-to-one, adding a redundant dimension for the same thing wastes a slot without adding new information.