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Resource Histogram

Available in: Pro · Enterprise
Last updated: 05-Mar-2026

Overview​

The Resource Histogram occupies the bottom-right quadrant of the Resources tab. It displays a stacked bar chart showing how much of each resource is allocated per time period. Bars that exceed the resource's maximum availability are highlighted in red to indicate over-allocation.

Use the histogram to spot resource bottlenecks, identify periods of under-utilisation, and validate that your resource plan is realistic.

Resource Usage histogram — budgeted bars and S-curveResource Usage histogram — budgeted bars and S-curve

Reading the Histogram​

Axes​

AxisWhat It Shows
Horizontal (X)Time periods — weeks, months, or quarters depending on your zoom level
Vertical (Y)Resource loading — hours, units, or cost depending on the selected metric

Bar Colours​

ColourMeaning
BlueNormal allocation — within the resource's maximum availability
RedOver-allocation — the resource is assigned more work than its capacity allows
GreyActual (completed) work — shows actual usage for past periods
Light blueRemaining work — planned but not yet completed

Capacity Line​

A horizontal dashed line shows the resource's Max Units/Time value. Any bar that extends above this line is over-allocated.

Time Period Options​

Use the period selector in the histogram toolbar to switch between:

PeriodBar WidthBest For
Weekly1 weekDetailed short-term analysis (1–3 months)
Monthly1 monthMedium-term planning (3–12 months)
Quarterly3 monthsPortfolio-level resource overview

The histogram automatically adjusts its scale when you change the period.

Metric Options​

Use the metric selector to switch between:

MetricDescription
UnitsResource loading in the resource's unit of measure (hours, tonnes, etc.)
CostResource loading expressed as cost (units × cost rate)

Interacting with the Histogram​

Hover​

Hover over any bar to see a tooltip with:

  • Time period (e.g., "Week of 15 Mar 2026")
  • Resource name
  • Budgeted units for the period
  • Actual units (if applicable)
  • Remaining units
  • Max available units
  • Over-allocation amount (if any)

Click​

Click a bar to select that time period. The Time-Phased Spreadsheet (top-right quadrant) scrolls to and highlights the corresponding column.

Zoom​

Use the mouse wheel or the zoom controls in the toolbar to zoom in or out on the timeline. Zooming in reveals more granular time periods; zooming out aggregates data.

Pan​

Click and drag horizontally to pan the histogram across the timeline. Alternatively, use the scroll bar at the bottom.

Synchronisation​

The histogram is synchronised with the other three quadrants:

InteractionEffect
Select a resource in the Resource GridHistogram filters to show only that resource's loading
Select multiple resourcesHistogram shows stacked bars for all selected resources
Click a node in the Resource HierarchyHistogram shows aggregated loading for all resources under that node
Click a bar in the histogramTime-phased spreadsheet scrolls to the corresponding period

Tips​

  • Start with the Monthly period for a high-level view, then switch to Weekly for detail.
  • Use the red over-allocation bars as your primary signal — these indicate schedule risk.
  • Compare actual (grey) vs. remaining (light blue) bars to assess how realistic the remaining plan is.
  • Select a parent node in the Resource Hierarchy to see aggregated loading for an entire resource category (e.g., all labour resources).

Troubleshooting​

ProblemSolution
Histogram shows no dataEnsure your schedule has resource assignments. Resources without assignments have no loading data.
All bars are greyYour data date is in the future. Grey bars represent actual (past) work. Check the data date in Project Properties.
Over-allocation not highlightedVerify the resource's Max Units/Time is set correctly. A value of 0 disables the capacity line.