Yamazumi BuilderFree Yamazumi Chart Builder

What is a Yamazumi Chart?

A Yamazumi chart — also called an operator balance chart or work balance chart — is a stacked bar chart that places every operator on a production line side by side, with each operator's work elements stacked vertically into a single bar. A horizontal line drawn at the takt time crosses all the bars simultaneously, making it immediately visible which operators are over pace (bar above the line) and which carry slack (bar below the line). In the default view, elements are coloured by the unit zone they touch — right side, left side, front, rear, or any layout area you define. Zone coloring drives line-layout decisions: you can immediately spot when right-side-of-unit work is assigned to an operator standing on the left, creating unnecessary walking. That spatial insight is what separates a Yamazumi from a plain bar chart of cycle times and is the reason line balancing teams reach for it first.

Toggle X-ray mode to reveal the value structure hidden inside each element. VA/NNVA/waste are not properties of a whole work element — they live as a composition within it. “Install bracket,” for example, might be 60% value-added (the actual installation) plus 20% necessary non-value-added (positioning) plus 20% waste (walking to retrieve the part). X-ray mode subdivides each bar slice by those proportions, coloured green, amber, and red, so the true waste structure becomes visible without changing the underlying element data.

Because every element is sized by its lowest repeatable time — the fastest consistent performance a skilled operator achieves under normal conditions, captured with a Time Observation Sheet — the chart reflects genuine capacity rather than padded averages. The operator balance chart becomes the team's shared reference during every rebalancing event: it shows the current state in one view and, once elements are moved, the future state in the same view.

How to read a Yamazumi chart

Consider the demo data loaded in the builder above: a six-operator line with a takt time of 60 seconds and 290 seconds of total work content. Divide 290 by 60 and you get 4.83 — rounded up to 5 theoretical operators. The line is currently staffed with 6, which means there is roughly one full operator of rebalancing opportunity sitting in the chart waiting to be found. Bars above the takt line identify overburden — the operator at that station cannot keep pace with customer demand and will create a queue or fall behind. Large gaps between the top of a bar and the takt line are waiting waste: the operator finishes early and stands idle until the next cycle begins. Both conditions are immediately visible in the zone-coloured stacked view; neither is obvious in a table of cycle time numbers. In the default view, each element's colour shows which part of the unit it touches, making it easy to spot layout mismatches — right-side work assigned to a left-side operator, for instance.

X-ray mode adds a deeper layer. That same six-operator line carries 60 seconds of waste content spread across multiple elements as fractional composition — not as separate “waste elements,” but as the non-value-added portion inside otherwise productive steps. Eliminate that waste and total work content drops to 230 seconds: 230 ÷ 60 = 3.83 — rounded up to 4 theoretical operators. Two improvement steps (redistribution plus waste reduction) could take the line from 6 operators to 4, a 33 percent productivity improvement that is fully visible in the chart before a single change is made on the floor. Use the drag-and-drop rebalancing feature to redistribute elements between operators and watch the bars reshape in real time; the theoretical staffing figure updates automatically at each step.

Yamazumi vs. SWCT

The Yamazumi chart and the Standardized Work Combination Table answer different questions and work best as a pair. The Yamazumi is a whole-line view: every operator's total work content stacked side by side against takt. It answers which station is overloaded and by how much, and it shows where slack exists that could absorb moved elements. When a line is out of balance, the Yamazumi is where the conversation starts — it gives the team a shared picture of the problem before anyone touches a stopwatch or a whiteboard.

The Standardized Work Combination Table (SWCT) zooms into a single operator's cycle and plots manual work, machine (auto) time, walking, and waiting in time sequence. It answers which specific elements can actually move, because it exposes machine-time constraints and sequencing dependencies that a stacked bar hides entirely. An element that looks movable on the Yamazumi may be locked in place by a machine interlock visible only on the SWCT. The practical workflow is: open the Yamazumi to find the imbalance, then open the SWCT for the overloaded and underloaded stations involved. The Yamazumi tells you where to look; the SWCT tells you what you can actually do.

Related tools

• Standardized Work Combination Table — one operator's manual/auto/walk interplay vs takt
• Time Observation Sheet — capture the element times that feed the chart
• Process Capacity Sheet — machine capacity and bottlenecks
• Takt Time Calculator — calculate the takt baseline