Why volume decides profit
Every business carries two kinds of cost. Variable costs rise with each unit sold: materials, packaging, payment fees, delivery. Fixed costs stay put in the short run: rent, salaries, insurance, software subscriptions.
Cost-volume-profit (CVP) analysis uses that split to answer four practical questions. How many units must we sell to break even? What profit will we make at a given volume? How much can sales fall before we make a loss? And how much does profit move when sales move?
The central idea is contribution: what is left of the selling price after variable costs. Each sale contributes that amount towards fixed costs, then towards profit.
Key points
- Variable cost per unit is constant across the relevant range.
- Fixed costs do not change with volume in the short run.
- Contribution is the bridge between sales and profit.
The CVP toolkit
CM = Price − Variable cost per unit
The cash each sale leaves behind to cover fixed costs.
- Price
- Selling price per unit
- Variable cost
- Direct cost per unit
CM ratio = CM ÷ Price
The share of every taka of sales that survives variable costs.
Break-even units = Fixed costs ÷ CM
The volume at which contribution covers fixed costs exactly.
Units = (Fixed costs + Target profit) ÷ CM
The volume needed to deliver a planned profit.
MoS = (Expected units − Break-even units) ÷ Expected units
How far sales can fall before the business makes a loss.
DOL = Contribution ÷ Operating profit
The multiple by which a change in sales is amplified into a change in profit.
The margin of safety is a risk measure. A business with a thin margin of safety has little room to be wrong about demand.
Nova Manufacturing at 9,000 units
Nova sells a product at ৳420 with a variable cost of ৳215, so each unit contributes ৳205. Monthly fixed costs are ৳780,000.
Break-even is ৳780,000 ÷ ৳205 = 3,804.88 units, or about ৳1,598,049 of revenue. At the planned volume of 9,000 units, profit is (9,000 × ৳205) − ৳780,000 = ৳1,065,000.
The margin of safety is (9,000 − 3,804.88) ÷ 9,000 = 57.7%, so sales could fall by more than half before Nova reached a loss. Operating leverage is ৳1,845,000 ÷ ৳1,065,000 = 1.73, meaning a 10% fall in sales would cut operating profit by roughly 17.3%.
Key points
- CM ratio = ৳205 ÷ ৳420 = 48.8% of every taka of sales.
- Operating leverage of 1.73 magnifies both gains and losses.
- A 57.7% margin of safety is comfortable room to absorb a demand shock.
Reading the analysis like a manager
CVP turns a price or cost decision into a volume decision. To earn a profit of ৳1,500,000, Nova needs (780,000 + 1,500,000) ÷ 205 = 11,121.95 units. That number, not the price itself, is what a sales plan has to beat.
The three levers behave differently. Raising price lifts contribution per unit and lowers break-even, but may reduce demand. Cutting variable cost does the same without touching demand, which is why it is usually the safest lever. Reducing fixed cost lowers the volume needed but may reduce capacity or quality.
Fixed costs are the source of operating leverage. A business with high fixed costs earns more on every extra sale once it passes break-even, and loses more on every lost sale before it gets there. That is a deliberate trade-off, not an accident.
Key points
- State decisions as volumes: units to break even, units to hit a target profit.
- Lowering variable cost improves profit at every volume level.
- High fixed costs mean high leverage in both directions.
Interactive experiment
Cost-volume-profit
CVP separates costs that move with volume from costs that do not, then finds the volume where profit is zero.
Profit = (Price − Variable cost) × Units − Fixed costs
Your inputs
Costs that do not change with volume.
Average selling price.
Direct cost of one unit.
Planned volume.
Result
- Contribution margin / unit
- ৳205
- Break-even units
- 3,804.9
- Profit at expected volume
- ৳1,065,000
- Contribution margin ratio
- 48.8%
- Break-even revenue
- ৳1,598,049
- Margin of safety (units)
- 5,195.1
- Degree of operating leverageA 1% sales change moves operating profit by this multiple.
- 1.73×
The business breaks even at 3,805 units and makes a profit beyond that.
03 / Apply
A monthly plan for Rise Bakery
Rise Bakery has monthly fixed costs of ৳120,000. Each box sells for ৳60 and carries ৳24 of variable cost. The owner plans to sell 5,000 boxes this month and wants to know how safe that plan is.
The assumptions
- Fixed costs cover rent, salaries, and equipment lease.
- Variable cost covers ingredients and packaging per box.
- The relevant range is 0 to 8,000 boxes per month.
What to take away
01
Contribution of ৳36 per box covers fixed costs first, then profit.
02
Break-even is 3,333.33 boxes, so the plan has room to fall.
03
Operating leverage of 3 makes profit sensitive to a slow month.
Your turn
0 of 4 answered
01Question
Rise Bakery sells each box for ৳60 with a variable cost of ৳24. What is the contribution margin per box?
02Question
With fixed costs of ৳120,000 and a contribution margin of ৳36, what is the break-even volume in boxes? Round to two decimals.
03Question
At 5,000 boxes, what is the monthly operating profit?
04Question
Which single change lowers the break-even volume?
Take it into the Lab
Experiment with the same idea.
The Lab turns this topic into a workspace: change the drivers, watch the statements move, and see the consequence before you commit to a decision.
What-if analysis
Change price, cost, and working capital. Watch margins, return, and risk move together.
Open the labFormula lab
Understand, manipulate, observe, solve, then apply the formula to a decision.
Walk the formulaStatement playground
See how one driver propagates through the income statement, balance sheet, and cash flow.
Open the playgroundSources & further reading
OpenStax · Principles of Accounting, Volume 2 (free textbook) ↗Educational sample content. Worked examples use hypothetical figures. Dates refer to the note's latest content update.