Many people start businesses with excellent products but limited understanding of the numbers behind them. They know what the product does, but not exactly what it costs to make, what margin distributors and retailers need, what it costs to run the business or how much profit is left. They price by copying competitors, perhaps a dollar cheaper, and hope for the best. When cash runs short, they cannot tell whether the problem is product cost, overheads or price.
Business educators often teach a simple benchmark to bring discipline to these questions: the one-third rule. Divide each dollar of revenue into three parts:
- One third for product cost: the direct cost of making or delivering what you sell.
- One third for operating cost: everything it takes to run the business and get the product to customers.
- One third for profit before tax.
Few businesses hit exactly one third in each category, and many industries operate on very different proportions. But as a starting benchmark, the rule is surprisingly useful. It forces you to understand your cost structure, gives owners and managers a shared target and highlights where to act when profit falls short. This article explains the rule, shows how to apply it to product and service businesses, and sets out its limitations.
The three thirds
First third: product cost
The direct cost of producing what you sell:
- Manufacturers: raw materials, components, packaging, direct labour and production consumables.
- Retailers and distributors: the purchase cost of goods.
- Service businesses: the direct cost of delivering the service, mainly the time of the people who deliver it.
If a product sells for $100, the one-third rule suggests its product cost should be around $33.
Second third: operating cost
Everything else needed to run the business and reach customers:
- Salaries of people not directly producing the product: management, sales, administration.
- Rent, utilities and insurance.
- Marketing and advertising.
- Channel costs: distributor and retailer margins, sales commissions and platform fees.
- Depreciation, interest, IT and professional fees.
Third third: profit before tax
What remains after product and operating costs. Tax is then paid on this profit, and the rest can be reinvested, held as a reserve or distributed to owners.
Examples
Some highly profitable listed companies come close to the one-third pattern. Training material on the rule cites examples of Indian consumer products, diagnostics and online recruitment companies with product or direct costs around 26 to 41 per cent of revenue, operating costs around 27 to 40 per cent and pre-tax profit around 30 to 33 per cent.
These are exceptional businesses with strong brands, scale and pricing power. Many small businesses earn much lower pre-tax margins, often in single digits, depending on their industry. That is exactly why the benchmark is useful: it shows how far a business is from a highly profitable structure, and where the gap lies.
Applying the rule to your business
Take your last financial year’s profit and loss statement and calculate:
| Item | Amount | % of revenue | One-third benchmark |
|---|---|---|---|
| Revenue | 100% | 100% | |
| Product or direct cost | about 33% | ||
| Operating cost | about 33% | ||
| Profit before tax | about 33% |
Then ask:
- Is product cost well above a third? Look at pricing, product design, materials, suppliers, waste, rework and labour efficiency.
- Is operating cost well above a third? Look at overheads, channel margins, marketing efficiency, staffing levels and underused premises or equipment.
- Is profit well below a third? Both of the above, plus whether your price reflects the value you deliver.
The rule’s message is simple: either grow revenue at good margins or optimise costs until the structure moves towards one third, one third, one third.
A worked example: a product sold through distributors
A small company manufactures a cleaning product. Its recommended retail price is $20.
The retailer needs a margin of about 35 per cent of the retail price, so buys at $13. The distributor needs about 15 per cent of its selling price, so buys from the manufacturer at about $11.05. The manufacturer’s revenue per unit is therefore $11.05, not $20.
Applying the one-third rule to the manufacturer’s revenue:
- Product cost should be about $3.68 per unit.
- Operating cost about $3.68.
- Profit about $3.68.
If the product actually costs $6.50 to make, product cost is 59 per cent of the manufacturer’s revenue, and the business will struggle to make a profit, whatever its sales volume. The options are to reduce product cost, raise the retail price, negotiate channel margins, sell some volume directly at higher margins, or redesign the product.
This example shows a common trap: founders compare their manufacturing cost with the retail price ($6.50 against $20 looks healthy) instead of with the price they actually receive.
The article on pricing your product or service explains pricing methods, and the article on gross margin and pricing power explains why margins matter so much.
Applying the rule to services
Professional services firms, such as engineering consultancies, accounting practices and design studios, have long used a similar rule of thumb: one third of revenue for the salaries of the people doing the work, one third for overheads and one third for profit. In practice, this translates into a billing guideline: each fee earner should generate roughly three times their salary cost in fees.
An illustration
An engineer costs the firm $120,000 a year in salary and on-costs. Under the one-third rule, the firm needs that engineer to generate about $360,000 in fees a year. If the engineer bills 1,400 hours a year, the charge-out rate needs to be around $257 an hour.
If the firm charges $180 an hour, or the engineer bills only 1,000 hours because of poor utilisation, profit will fall far short. The rule helps the firm think about both rates and utilisation.
Many firms operate on lower multiples, depending on their market, but the logic of linking salary, overheads, rates and utilisation holds.
Why the rule helps
- A clear benchmark: everyone understands the target structure.
- Shared direction: owners and managers work towards the same proportions.
- Profit focus: the rule treats profit as a planned outcome, not whatever is left over.
- Healthier cash reserves: consistent profit builds cash for investment and difficult times.
- Early warning: when a cost category drifts above its share, you notice and act.
Limitations
The one-third rule is a heuristic, not a law:
- Industry structures differ. Supermarkets operate on thin margins and high volume. Software businesses may have very low product costs and high development and sales costs. Construction contractors often have high direct costs and lower margins.
- Growth stages differ. A start-up investing heavily in marketing or a scaling business adding staff ahead of revenue will temporarily have high operating costs.
- Volume matters. A business with thin margins but very high volume and fast stock turnover can be highly profitable in absolute terms.
- Classification matters. Whether a cost counts as product or operating cost varies between businesses. Be consistent over time.
- Competition sets limits. In some markets, prices that would deliver one-third profits are not achievable.
Use the rule to ask questions, not as a rigid target. Compare your results with industry benchmarks where available, such as those the ATO publishes for many small business industries, and with your own trend over time.
Margin versus markup
A frequent source of confusion is the difference between margin and markup, which can make a business think it is following the one-third rule when it is not.
- Markup is profit expressed as a percentage of cost. Buying at $10 and selling at $15 is a 50 per cent markup.
- Margin is profit expressed as a percentage of the selling price. The same sale has a margin of $5 ÷ $15, or 33 per cent.
The one-third rule is expressed as shares of revenue, so it uses margin. If product cost is to be one third of the selling price, the selling price must be three times product cost, a markup of 200 per cent. Many businesses that apply a 50 or 100 per cent markup believe they have healthy margins, but are far from the benchmark.
| Markup on product cost | Product cost as % of price | Remaining for operating cost and profit |
|---|---|---|
| 50% | 67% | 33% |
| 100% | 50% | 50% |
| 150% | 40% | 60% |
| 200% | 33% | 67% |
Tracking the thirds over time
Calculate the three shares every month or quarter, not just once a year. Trends reveal problems early: a gradual rise in product cost as material prices climb, a creeping increase in operating costs as the team grows, or a drop in profit share as discounting spreads. The article on running a weekly business review explains how to build regular financial review into management routines.
Using the rule when launching a product
When designing a new product, work backwards:
- Estimate the price customers will pay, based on value and market research.
- Subtract channel margins to find your net revenue per unit.
- Set a target product cost of around a third of net revenue.
- Design the product to meet that target, choosing materials, processes and suppliers accordingly.
- Check that operating costs and expected volumes leave a healthy profit.
This “target costing” approach prevents the common mistake of designing a product first and discovering later that it cannot be sold profitably.
A worked example: rebalancing a business
A manufacturer of steel shelving has revenue of $4 million. Its profit and loss shows:
- Product cost: $2.4 million (60 per cent).
- Operating cost: $1.3 million (32.5 per cent).
- Profit before tax: $300,000 (7.5 per cent).
Operating cost is close to the benchmark, but product cost is far above it. The owner investigates and finds that steel prices have risen without corresponding price increases, scrap rates are high on one product line and a third of sales go to a single large customer at very low margins.
Over two years, the business raises prices on most lines by an average of 6 per cent, cuts scrap through better nesting software and operator training, renegotiates the large customer’s contract and introduces a premium range with better margins. Product cost falls to 48 per cent of revenue, revenue grows modestly and profit before tax rises to about 18 per cent. Not one third, but a dramatic improvement, and the business has a clear direction for further gains.
Frequently asked questions
Does the rule include the owner’s salary? It should. Include a fair market salary for the owner’s work in operating or direct costs, as appropriate, so profit reflects the return on the business, not unpaid owner labour.
What if my industry’s margins are naturally thin? Use industry benchmarks as your main reference, and use the one-third rule as a reminder to examine every cost category and to look for higher-margin opportunities within your industry.
How does the rule apply to a retailer? For a retailer, product cost is the purchase price of goods. A retailer whose purchase costs are around a third of its selling prices has room for operating costs and profit. Many retailers operate with higher product costs and lower margins, relying on volume and stock turnover, so compare your figures with industry benchmarks as well as the rule.
Should I aim for one-third profit before investing in growth? Not necessarily. Investing in growth can temporarily lower profit. The key is that the investment is deliberate, with a clear expectation of future returns.
Summary
The one-third rule divides revenue into three roughly equal parts: product cost, operating cost and profit before tax. It provides a simple benchmark for understanding your cost structure, setting targets and spotting problems early. Apply it to your actual net revenue after channel margins, and to services through the relationship between salaries, overheads, rates and utilisation. Use it to guide pricing and product design through target costing. Recognise its limits: industries, growth stages and volumes differ. Above all, use it to ask the right questions and to treat profit as something you plan, not something left over.
Sources: small-business training notes on the one-third framework for running a business, together with general management accounting practice. Company examples are as reported in those notes, and other figures are illustrations. This article is general information, not financial advice.
