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A bottleneck is the process step, machine, or resource that limits the overall throughput of a production or service system. No matter how efficiently all other steps operate, a system can only produce as fast as its slowest (most constrained) step. A bottleneck calculator helps operations managers identify the constraining resource using the Theory of Constraints (TOC), developed by Dr. Eliyahu Goldratt, and quantifies the cost of the bottleneck in terms of lost throughput and revenue. The calculator takes input on each process step's capacity (units per hour), current demand load, and setup/downtime, then identifies which step has the lowest available capacity relative to demand — the bottleneck. It then calculates: throughput loss (units not produced due to the constraint), revenue lost per hour of bottleneck downtime, the financial benefit of increasing bottleneck capacity by one unit of time, and the priority ranking for improvement investments. Goldratt's Five Focusing Steps prescribe how to manage the bottleneck: (1) Identify it; (2) Exploit it (maximize its output with current resources); (3) Subordinate everything else to the bottleneck's pace; (4) Elevate it (invest to increase capacity); (5) Repeat. Understanding that only the bottleneck determines system throughput is counterintuitive but powerful: improving non-bottleneck steps adds zero throughput unless the bottleneck is also improved. This insight prevents misallocation of improvement resources to non-constraining processes.
System Throughput = min(Capacity of all process steps) Bottleneck Step = argmin(Capacity_i for i = 1 to n) Throughput Loss = (Demand Rate − Bottleneck Capacity) × Production Hours Cost of Bottleneck = Throughput Loss × Contribution Margin per Unit Bottleneck Utilization = Demand Rate / Bottleneck Capacity × 100 Capacity Buffer = (Step Capacity − Bottleneck Capacity) / Bottleneck Capacity × 100
- 1List all process steps in sequence with their maximum capacity (units per hour or per shift).
- 2Enter the demand rate (required throughput) for the system.
- 3Identify the step with the lowest capacity — this is the bottleneck.
- 4Calculate bottleneck utilization = demand / bottleneck capacity × 100.
- 5If utilization > 100%, the system cannot meet demand — calculate the throughput gap.
- 6Calculate revenue/margin lost per hour of bottleneck downtime.
- 7Evaluate investment options to increase bottleneck capacity (overtime, cross-training, equipment).
Despite Cutting, Painting, and Assembly having capacity ≥80 units/hr, the whole line is capped at 65 because Welding can't keep up. Every improvement to non-welding steps is wasted investment until welding is resolved.
Every 30 minutes of unplanned downtime at the bottleneck costs $1,462. A $200 preventive maintenance procedure to avoid this downtime has a payback under 15 minutes of prevented downtime.
TOC Drum-Buffer-Rope: Drum = bottleneck pace, Buffer = protective inventory ahead of bottleneck, Rope = material release rate tied to drum. Non-bottleneck steps slow to drum rate — reducing WIP inventory.
Increasing bottleneck capacity from 65 to 85 units/hr — an investment of $120K — generates $3.6M in additional annual margin. 12-day payback makes this one of the highest-ROI investments in the plant.
Plant managers identifying the single constraining resource to focus improvement investment. This application is commonly used by professionals who need precise quantitative analysis to support decision-making, budgeting, and strategic planning in their respective fields
Hospital administrators identifying bottlenecks in patient flow (ED wait times, OR scheduling). Industry practitioners rely on this calculation to benchmark performance, compare alternatives, and ensure compliance with established standards and regulatory requirements
Software development teams identifying the bottleneck in their deployment pipeline. Academic researchers and students use this computation to validate theoretical models, complete coursework assignments, and develop deeper understanding of the underlying mathematical principles
Supply chain analysts identifying the constraining node in a distribution network. Financial analysts and planners incorporate this calculation into their workflow to produce accurate forecasts, evaluate risk scenarios, and present data-driven recommendations to stakeholders
{'case': 'Floating Bottleneck', 'note': 'Some systems have a bottleneck that shifts depending on the product mix — Product A is bottlenecked at welding, Product B at painting. Dynamic scheduling must continuously reidentify the constraint based on the current production plan and manage capacity accordingly.'} When encountering this scenario in bottleneck calc calculations, users should verify that their input values fall within the expected range for the formula to produce meaningful results. Out-of-range inputs can lead to mathematically valid but practically meaningless outputs that do not reflect real-world conditions.
{'case': 'Policy Constraints', 'note': "Often the true constraint is a management policy rather than a physical capacity limit. 'We only run 1 shift' or 'We don't accept orders larger than X' are policy constraints that can double throughput instantly when relaxed. Identify physical constraints first, then question whether they're reinforced by policy constraints."}
In systems with variability and queues, Little's Law (L = λW) helps identify true bottlenecks: the step with the longest queue and highest WIP inventory ahead of it is likely the constraint."} In the context of bottleneck calc, this special case requires careful interpretation because standard assumptions may not hold. Users should cross-reference results with domain expertise and consider consulting additional references or tools to validate the output under these atypical conditions.
| Step | Capacity (units/hr) | Utilization vs. 80/hr Demand | Status |
|---|---|---|---|
| Cutting | 120/hr | 66.7% | Non-constraint |
| Welding | 65/hr | 123.1% | BOTTLENECK |
| Painting | 95/hr | 84.2% | Non-constraint |
| Assembly | 110/hr | 72.7% | Non-constraint |
This relates to bottleneck calc calculations. This is an important consideration when working with bottleneck calc calculations in practical applications. The answer depends on the specific input values and the context in which the calculation is being applied. For best results, users should consider their specific requirements and validate the output against known benchmarks or professional standards.
This relates to bottleneck calc calculations. This is an important consideration when working with bottleneck calc calculations in practical applications. The answer depends on the specific input values and the context in which the calculation is being applied. For best results, users should consider their specific requirements and validate the output against known benchmarks or professional standards.
This relates to bottleneck calc calculations. This is an important consideration when working with bottleneck calc calculations in practical applications. The answer depends on the specific input values and the context in which the calculation is being applied. For best results, users should consider their specific requirements and validate the output against known benchmarks or professional standards.
This relates to bottleneck calc calculations. This is an important consideration when working with bottleneck calc calculations in practical applications. The answer depends on the specific input values and the context in which the calculation is being applied. For best results, users should consider their specific requirements and validate the output against known benchmarks or professional standards.
This relates to bottleneck calc calculations. This is an important consideration when working with bottleneck calc calculations in practical applications. The answer depends on the specific input values and the context in which the calculation is being applied. For best results, users should consider their specific requirements and validate the output against known benchmarks or professional standards.
This relates to bottleneck calc calculations. This is an important consideration when working with bottleneck calc calculations in practical applications. The answer depends on the specific input values and the context in which the calculation is being applied. For best results, users should consider their specific requirements and validate the output against known benchmarks or professional standards.
This relates to bottleneck calc calculations. This is an important consideration when working with bottleneck calc calculations in practical applications. The answer depends on the specific input values and the context in which the calculation is being applied. For best results, users should consider their specific requirements and validate the output against known benchmarks or professional standards.
プロのヒント
Mark your bottleneck physically in the plant — a sign, colored floor tape, or a status board. This focuses everyone's attention: maintenance prioritizes this machine, operators never let it wait, and management reviews its performance daily. Physical visibility of the constraint is one of the highest-impact, lowest-cost improvements you can make.
ご存知でしたか？
Eliyahu Goldratt published TOC in the form of a novel, 'The Goal' (1984), about a factory manager saving his plant from closure by applying constraint theory. It has sold over 7 million copies and is mandatory reading at business schools including Harvard. Boeing, Ford, and the US military have all applied TOC to dramatically improve production throughput.