Why profits move faster than sales
A business with large fixed costs, such as rent, salaries, software or aircraft, has to cover them whatever it sells. Below the break-even point it loses money; above it, most of each extra sale drops to the bottom line. That amplification is operating leverage. Debt adds a second layer, financial leverage, because interest is also fixed.
The formulas
- Contribution margin = revenue − variable costs
- Operating profit (EBIT) = contribution margin − fixed operating costs
- Degree of operating leverage: DOL = contribution margin ÷ EBIT
- Degree of financial leverage: DFL = EBIT ÷ (EBIT − interest)
- Degree of total leverage: DTL = DOL × DFL
Each degree is an elasticity: a 1% change in sales changes EBIT by DOL percent and pre-tax profit by DTL percent.
Worked example
A company has $1,000,000 of revenue, $600,000 of variable costs, $250,000 of fixed operating costs and $50,000 of interest:
- Contribution margin: $400,000, a 40% ratio.
- EBIT: $150,000; pre-tax profit: $100,000.
- DOL: 400,000 ÷ 150,000 = 2.67.
- DFL: 150,000 ÷ 100,000 = 1.50.
- DTL: 4.00.
If sales rise 10%, EBIT rises 26.7% and pre-tax profit 40%. If sales fall 10%, they fall by the same percentages. Break-even revenue is 250,000 ÷ 0.40 = $625,000, so sales could fall 37.5%, the margin of safety, before operating profit hits zero.
Reading the result
- High DOL (above about 3): software, airlines, hotels, telecoms, manufacturers with expensive plants. Great in growth, painful in a downturn.
- Low DOL (close to 1): retailers and consultancies, whose costs are mostly variable.
- DOL very high or negative: the business is near or below break-even, where small changes in sales make huge percentage swings in a small profit.
A high DOL combined with a high DFL makes earnings very volatile. Lenders and investors watch both.
Using it in planning
- Moving costs from fixed to variable, for example outsourcing or paying commissions instead of salaries, lowers DOL and risk but also lowers the upside.
- Before signing a long lease or buying equipment, check how far sales could fall before you lose money.
- The degrees change as sales change, so recalculate them at the new level.
The model assumes a constant selling price, a constant variable cost per unit and fixed costs that do not step up. That holds for moderate changes; a large expansion usually needs new fixed costs.
This calculator gives estimates for education and planning. It is not investment, tax or legal advice; for decisions about your own situation, talk to a qualified financial professional.