What it means
Variable costs are those that move roughly in proportion to activity, in contrast to fixed costs such as rent, salaries and insurance, which continue whether or not anything is sold. The ratio expresses those variable costs as a percentage of sales rather than as an absolute amount.
The number matters because it tells managers what an extra dollar of revenue is actually worth to the business. A company with a variable cost ratio of 40% keeps 60 cents of each new sales dollar, so growth is highly profitable, while a company at 85% has to sell an enormous amount before fixed costs are covered.
It is calculated by dividing total variable costs by total sales for the same period, and it can be computed for the whole business, a product line or a single order. The same ratio drives break-even analysis, because break-even sales equal fixed costs divided by one minus the variable cost ratio.
The main practical difficulty is deciding which costs are genuinely variable, since many costs are semi-variable and only move in steps. A supervisor's salary is fixed until volume forces a second shift, at which point it jumps.
The ratio also shifts with product mix, so a business can watch its ratio deteriorate without any single cost rising, simply because it sold more of the low-margin lines. Tracking it by product rather than only in total avoids that particular blind spot.
In practice
Real-world examples.
Example
A print shop finds its variable cost ratio has drifted from 58% to 66% over two years. Investigation shows paper prices rose while list prices did not, and a single price increase restores the previous ratio.
Example
A software business runs at a variable cost ratio of just 12%, since hosting and payment fees are its only volume-driven costs. Its board accepts heavy fixed spending on engineering because each new customer contributes 88 cents in the dollar.
Example
A catering company quotes a large event at a discount and checks the ratio before agreeing. Food and agency staff come to 72% of the quoted price, still positive, so the job is accepted to fill an otherwise quiet week.
Formula
Calculation
Variable cost ratio = Total variable costs / Sales.
A packaging business records sales of $2,000,000 in a year with variable costs of $1,300,000 covering board, ink, freight and commission. The variable cost ratio is $1,300,000 / $2,000,000 = 0.65, or 65%, which leaves a contribution margin ratio of 35% and contribution of $700,000. Fixed costs are $500,000, so operating profit is $700,000 - $500,000 = $200,000, and break-even sales are $500,000 / 0.35 = $1,428,571. Every additional $100,000 of sales at the same mix adds $100,000 x 0.35 = $35,000 of profit.Case study
Seen in the real world.
Brackwell Beverages is a fictional drinks bottler used here as an illustrative case. Revenue had grown 18% over two years while operating profit had fallen, and the management team could not explain the gap from the summary accounts alone.
Splitting the numbers by product revealed the answer. The core still water line ran at a variable cost ratio of 55%, but a new flavoured range, which had driven almost all the growth, ran at 78% because of expensive concentrate and heavier glass bottles. Group sales of $9,000,000 now carried $6,120,000 of variable cost, a blended ratio of 68% against 60% two years earlier.
The illustrative company renegotiated the concentrate contract, moved the flavoured range to lighter bottles and raised its price by 9%. The flavoured line's ratio fell to 66%, and group contribution rose by roughly $500,000 without any change in volume.
Watch out
Common mistakes.
- Treating every cost that changed during the year as variable, when many of those movements were price increases on fixed items rather than volume effects.
- Reading a rising variable cost ratio as a supplier problem, when it is often caused by a shift in the mix of products sold.
- Using the total company ratio to price an individual job, which hides the fact that different products behave very differently.
Questions
People also ask.
How is it different from the contribution margin ratio?
They always add up to 100%, so a variable cost ratio of 65% means a contribution margin ratio of 35%, and either one can be used for break-even work.
Is sales commission a variable cost?
Yes, if it is a percentage of each sale it rises directly with revenue, though a guaranteed minimum payment within it behaves as a fixed cost.
Does a low variable cost ratio always mean a better business?
Not automatically, because a very low ratio usually comes with heavy fixed costs, which makes the business more profitable in good years and more exposed in bad ones.
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