Power BI adds calculated columns to Direct Lake tables
Microsoft released the April 2026 Power BI update with calculated columns now available on Direct Lake tables from OneLake. The addition covers unmaterialized columns and calculated tables that reference lake data. It requires a feature switch in Power BI Desktop and remains in preview with service deployment still pending. Users can run these calculations without importing or duplicating the full dataset. This extends Direct Lake capabilities beyond basic queries to include Excel-style computed fields. Limitations include the preview status and the need to enable the switch manually for each model.
Before this change, Direct Lake mode forced analysts to switch to import mode for any meaningful calculations. That switch duplicated data and produced the multi-hour refresh cycles that plague inherited reports with hundreds of steps. The update now lets calculations run directly on lake data, which cuts storage overhead and speeds up refreshes for large volumes. The practical difference for teams still relying on Excel exports is that familiar DAX patterns become usable without rebuilding the entire model from scratch.
Analysis
Treat this as a narrow test opportunity rather than a reason to overhaul everything. Enable the feature switch in Power BI Desktop right now and add one basic calculated column to a small Direct Lake table connected to your existing sources.
Citation
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