Line Balancing Worksheet with Balance Efficiency
Line balancing spreads the work content of a product across stations so that every station takes roughly the same time and none exceeds takt. This worksheet takes your station times and takt time, then shows how loaded each station is, where the idle time sits and how good the balance is overall.
| Station | Tasks assigned | Operators | Work content (sec) (sec) | Takt time (sec) (sec) | Load vs takt | Idle time (sec) | |
|---|---|---|---|---|---|---|---|
86.7% | 8 | ||||||
96.7% | 2 | ||||||
78.3% | 13 | ||||||
100% | 0 | ||||||
68.3% | 19 | ||||||
91.7% | 5 |
Edit any cell, add a row per station and export to Excel. If a station time exceeds takt, the line cannot meet demand without another operator, a split task or a parallel station.
Pull routing times from your ERP into a balancing view
Optional: we can review how your ERP stores routing and labor standards and show how to feed them into a live line balance.
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How to use the worksheet
List one row per station and enter the total work content in seconds for one unit, including any machine time the operator must wait on. Enter takt time on each row; it normally comes from available time divided by customer demand. The worksheet calculates load against takt, idle seconds per station, and the summary balance efficiency. Replace the sample rows with your own, add rows for extra stations, and export to Excel to build a yamazumi stacked bar chart from the same columns.
- Use observed times from a time study, not standard minutes from the routing, when they differ.
- Put the number of operators in the Operators column; load is calculated per operator.
- Keep takt the same on every row unless stations serve different products.
The formulas behind it
Station load equals work content divided by takt times operators, shown as a percentage. Idle time is takt times operators minus work content, floored at zero. Balance efficiency equals total work content divided by the number of stations times the longest station time, which is the classic line efficiency used in textbooks on assembly line balancing. Balance delay is one hundred minus that. The theoretical minimum number of stations is total work content divided by takt, rounded up. These are the standard measures for the simple assembly line balancing problem.
Reading the results
In the sample line the total work content is 313 seconds across six stations at a 60 second takt. The longest station is 60 seconds, so balance efficiency is about 87 percent and the theoretical minimum is six stations. A station above 100 percent load is a hard constraint on output. Stations well below 80 percent are candidates for absorbing tasks from their neighbors. Move one task at a time and re-enter the times, because moving a task changes both stations and sometimes the walking and handling time as well.
Common mistakes
The most common error is balancing to the average instead of to the slowest station. The line runs at the pace of its slowest station, so average load can look fine while output suffers. Other mistakes include using routing standards that include allowances the floor does not actually take, ignoring precedence constraints when moving tasks, and balancing for a takt that changed when demand changed. Rebalance whenever takt, product mix or headcount changes materially.
Frequently Asked Questions
What is a good line balance efficiency?
Many manual assembly lines sit between 75 and 90 percent, and above 90 percent is usually hard to sustain with variable work. The right target depends on cycle variation, task precedence and how costly an extra operator is, so use the number to compare your own scenarios rather than as a benchmark.
What is the difference between takt time and cycle time here?
Takt time is the pace set by customer demand. Cycle time is how long a station actually needs per unit. A balanced line has station cycle times at or just under takt. If any station cycle time exceeds takt, the line falls behind demand.
Can I use this for a multi-model line?
Yes, if you enter a weighted average work content per station based on the product mix, or run one copy per model. For wide mix variation, check the worst-case model separately because an average can hide a station that overloads on one variant.
How do I export it to Excel?
Use the export bar on the tool to download the worksheet as an Excel file, PDF or CSV. The computed load and idle columns are included, so you can chart the station times against takt as a stacked bar chart.
If your routing times live in SyteLine, SAP, Epicor or another ERP, Netray can pull them into a balancing view that updates when routings or demand change.
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