What you'll learn
- How to tell fixed costs from variable costs, then calculate total cost and average unit cost.
- How revenue from sales links to profit or loss.
- How to calculate average rate of return (ARR) for investment projects such as machinery, buildings and vehicles.
- How to interpret break-even output and margin of safety from a break-even chart.
The big picture: why these numbers matter
Businesses use financial calculations to make decisions, not just to “do maths”. A café might use them to decide whether to raise prices, a bakery might use them before buying a new oven, and a large retailer like Tesco might use them when planning a new store.
Output means the number of units a business produces or sells in a period of time. For example, 500 sandwiches in a day or 2,000 pairs of trainers in a week.
Most GCSE finance calculations fit together like this:

Formulae are not given
In AQA GCSE Business, you need to memorise the key formulae. In calculations, always carry the unit: usually £, units, or %.
Costs: what the business spends
A cost is money a business spends in order to operate. Costs matter because a business can have strong sales but still struggle if its costs are too high.
Fixed, variable and total costs
- Fixed costs are costs that do not change with output over the period being considered, such as rent, insurance or a manager’s salary.
- Variable costs are costs that change directly with output, such as ingredients, packaging or raw materials.
- Total costs are all fixed costs plus all variable costs.
The two key cost formulae are:
total variable costs=variable cost per unit×output\text{total variable costs} = \text{variable cost per unit} \times \text{output}total variable costs=variable cost per unit×output total costs=fixed costs+total variable costs\text{total costs} = \text{fixed costs} + \text{total variable costs}total costs=fixed costs+total variable costsAverage unit cost
Average unit cost is the cost of producing one unit on average. It is useful when a business wants to compare efficiency, set prices, or see whether producing more units has reduced the cost per item.
average unit cost=total costsoutput\text{average unit cost} = \frac{\text{total costs}}{\text{output}}average unit cost=outputtotal costsCalculating total and average unit cost
A local café makes 500 sandwiches. Ingredients and packaging cost £1.20 per sandwich. Fixed costs for the day are £300.
- The ingredients and packaging change with each extra sandwich, so they are variable costs: £1.20\text{£}1.20£1.20 per sandwich.
- Calculate total variable costs: total variable costs=£1.20×500=£600\text{total variable costs} = \text{£}1.20 \times 500 = \text{£}600total variable costs=£1.20×500=£600.
- Add fixed costs to find total costs: total costs=£300+£600=£900\text{total costs} = \text{£}300 + \text{£}600 = \text{£}900total costs=£300+£600=£900.
- Divide total costs by output to find average unit cost: average unit cost=£900÷500=£1.80 per sandwich\text{average unit cost} = \text{£}900 \div 500 = \text{£}1.80\text{ per sandwich}average unit cost=£900÷500=£1.80 per sandwich.
Regular payment does not always mean fixed cost
A cost is fixed if it does not change with output in the period. Do not call a cost fixed just because it is paid regularly.
Revenue, profit and loss
Revenue, profit and loss
Revenue is the money earned from selling goods or services before costs are taken away. Profit happens when revenue is greater than total costs. Loss happens when total costs are greater than revenue.
The formula for revenue is:
revenue=selling price per unit×quantity sold\text{revenue} = \text{selling price per unit} \times \text{quantity sold}revenue=selling price per unit×quantity soldThe formula for profit or loss is:
profit or loss=total revenue−total costs\text{profit or loss} = \text{total revenue} - \text{total costs}profit or loss=total revenue−total costsIf the answer is positive, the business has made a profit. If the answer is negative, the business has made a loss.
Calculating revenue, profit and loss
JD Sports sells 80 hoodies at £30 each. The total cost of buying, staffing and displaying those hoodies is £1,900.
- Calculate revenue from sales: revenue=£30×80=£2,400\text{revenue} = \text{£}30 \times 80 = \text{£}2{,}400revenue=£30×80=£2,400.
- Subtract total costs from revenue: profit=£2,400−£1,900=£500\text{profit} = \text{£}2{,}400 - \text{£}1{,}900 = \text{£}500profit=£2,400−£1,900=£500.
- The answer is positive, so JD Sports has made a profit of £500 on these hoodie sales.
Revenue is not profit
High revenue does not automatically mean success. A business can sell lots of products and still make a loss if its costs are higher than its revenue.
Investment projects and average rate of return
An investment project is when a business spends money now to try to earn more profit in the future. GCSE examples include buying new machinery, opening or improving buildings, or purchasing vehicles.
A bakery might buy a new oven to increase output. A delivery firm might buy vans to serve more customers. A supermarket might invest in a new store building.
Average rate of return
Average rate of return (ARR) shows the average annual profit from an investment as a percentage of the original cost of the investment.
You need to memorise these formulae:
average annual profit=total profit over life of projectnumber of years\text{average annual profit} = \frac{\text{total profit over life of project}}{\text{number of years}}average annual profit=number of yearstotal profit over life of project ARR=average annual profitinitial cost of investment×100\text{ARR} = \frac{\text{average annual profit}}{\text{initial cost of investment}} \times 100ARR=initial cost of investmentaverage annual profit×100Calculating average rate of return
A local bakery is considering buying a delivery van for £24,000. It expects the van to generate total profit of £12,000 over 4 years.
- Find the average annual profit: average annual profit=£12,000÷4=£3,000\text{average annual profit} = \text{£}12{,}000 \div 4 = \text{£}3{,}000average annual profit=£12,000÷4=£3,000.
- Divide average annual profit by the initial cost: £3,000÷£24,000=0.125\text{£}3{,}000 \div \text{£}24{,}000 = 0.125£3,000÷£24,000=0.125.
- Convert to a percentage: ARR=0.125×100=12.5%\text{ARR} = 0.125 \times 100 = 12.5\%ARR=0.125×100=12.5%.
- Interpret the result: the van is expected to earn an average annual return of 12.5% on the original investment cost.
ARR is useful because it gives a clear percentage for comparing investment options. However, it is based on forecasts, so the real return could be different if costs rise, demand falls, or the vehicle needs repairs.
Using the wrong numerator
ARR uses average annual profit, not total profit and not total revenue. If you use £12,000 instead of £3,000 in the example above, your answer will be too high.
Break-even: when revenue equals costs
Break-even output and margin of safety
Break-even output is the level of output where total revenue equals total costs, so the business makes neither a profit nor a loss. Margin of safety is how far actual output is above break-even output.
The margin of safety is:
margin of safety=actual output−break-even output\text{margin of safety} = \text{actual output} - \text{break-even output}margin of safety=actual output−break-even outputA break-even chart is a graph showing fixed costs, total costs and total revenue. You use it to read off the break-even output and margin of safety.
You are expected to interpret break-even charts. You are not expected to draw them or use the break-even formula.

Do not use the break-even formula
For AQA GCSE Business, you identify break-even output from the chart. Do not spend time trying to draw a chart or use a break-even formula.
Interpreting a break-even chart
Using the café chart above:
- Find where the total revenue line crosses the total costs line. Reading down to the output axis gives a break-even output of 200 sandwiches.
- The actual output shown is 300 sandwiches, so calculate the margin of safety: margin of safety=300−200=100 sandwiches\text{margin of safety} = 300 - 200 = 100\text{ sandwiches}margin of safety=300−200=100 sandwiches.
- Because actual output is to the right of break-even, total revenue is higher than total costs, so the café is forecast to make a profit at 300 sandwiches.
Evaluating break-even analysis
Break-even analysis can be valuable because it gives a business a clear sales target. It can help with decisions about pricing, cost control, marketing targets and whether a new product seems realistic.
But it has limits. It relies on forecasts, and real businesses face changing costs, changing demand and competitors. A café may not sell every sandwich it makes. A retailer may need to discount products. A manufacturer may face rising material costs.
Break-even is a planning tool, not a guarantee
Break-even analysis is most useful when the data are realistic and the business uses it alongside other information, such as market research, capacity and cash-flow forecasts.
Evaluating break-even analysis for a café
A café plans to sell 300 sandwiches a day, and its break-even chart shows break-even output at 200 sandwiches.
- The chart is useful because it shows the café needs to sell at least 200 sandwiches to avoid a loss.
- The margin of safety is 100 sandwiches, so sales could fall by 100 before the café reaches break-even.
- However, if ingredient prices rise or fewer customers visit than expected, the total costs or revenue lines could change, reducing the accuracy of the forecast.
- A balanced judgement is that break-even analysis is helpful for setting targets, but the café should also use market research and monitor real sales and costs.
In the exam
- State the formula first for calculations such as revenue, total costs, average unit cost, profit and ARR, then substitute the numbers with £, units or %.
- Interpret the result in context: say what the answer means for the café, retailer or manufacturer in the question.
- For break-even charts, read the intersection for break-even output, subtract to find margin of safety, and remember you do not need to draw the chart or use a break-even formula.
Check yourself
- What is the difference between a fixed cost and a variable cost?
- A business has revenue of £8,000 and total costs of £6,500. What has it made, and how much?
- Why might break-even analysis be useful but not fully reliable for a new café?