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Break-even and margin per bottleneck hour

Paste products with price, variable cost, demand and bottleneck time to get break-even revenue, the monthly income statement and the mix that maximizes profit with existing capacity.

Pre-sizing and estimating tool: results do not replace design, calculations or reports signed by a licensed professional, nor verification against the applicable codes and standards.

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In the U.S. sales tax is not company revenue, so leave it at zero; use this field only for gross receipts taxes where they apply.

—Break-even point
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Percentage margin vs. margin per bottleneck hour

Product ranking changes when you look at the resource that limits output.

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Break-even chart

Revenue and total cost versus mix volume, as a percentage of the optimal mix.

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Monthly income statement

Products

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Method, assumptions and references

Equations used

Unit CM = price × (1 − sales taxes − commissions) − variable cost; CM% = CM ÷ price
Margin per bottleneck hour = CM ÷ (bottleneck minutes ÷ 60); the optimal mix fills bottleneck hours in that order, up to each product’s demand
Break-even = fixed costs ÷ average CM% of the mix; margin of safety = (revenue − break-even) ÷ revenue

Assumptions and limits

  • A single bottleneck resource; with several constraints the optimal mix needs linear programming.
  • Current mix = demand scaled down proportionally when capacity is short.

Standards and technical documents

  • Goldratt, E. M. The Haystack Syndrome. North River Press, 1990
  • Corbett, T. Throughput Accounting. North River Press, 1998
  • Horngren, C. T.; Datar, S. M.; Rajan, M. V. Cost Accounting: A Managerial Emphasis. Pearson

U.S. regulations

  • IRC §11: 21% federal corporate income tax rate; state taxes vary
  • ASC 606: revenue recognition

Frequently asked questions

How do I compute break-even with several products?

Compute the mix’s average contribution margin ratio (total contribution ÷ total revenue) and divide fixed costs by it. The result is the monthly revenue at which profit is zero.

Why look at margin per bottleneck hour?

Because when capacity is short, each bottleneck hour is worth what it earns. A high-margin product that takes long on the bottleneck can earn less than a lower-margin one.

What goes into variable cost?

Raw material, packaging, energy and consumables that scale with volume. Fixed labor and depreciation stay in fixed costs.