What is a variable cost?

Published Thursday 23 July 2026

Table of contents

• What is a variable cost?
• Examples of variable costs
• How to calculate variable costs
• Variable costs vs fixed costs
• What are stepped (semi-variable) costs?
• Why variable costs matter
• How to reduce variable costs
• Track your variable costs with Xero
• FAQs on variable costs

Key takeaways

• Variable costs rise and fall with your business activity, so they climb when you sell more and drop when things slow down.
• You work out total variable cost by multiplying the variable cost per unit by the number of units you make or sell.
• Variable costs are the opposite of fixed costs, which stay the same no matter how busy you are.
• Tracking variable costs helps you set accurate budgets, forecast cash flow, and understand your break-even point.

What is a variable cost?

A variable cost is an expense that goes up and down in line with your business activity. The busier you are, the higher it goes, and they are the opposite of fixed costs.

Many variable costs, such as inventory and freight, rise in line with the number of sales you make. But not all variable costs sync up this way. Spending on marketing, trade shows, or sales travel might aim to drive up sales, yet it won't always match your output perfectly.

Examples of variable costs

Variable costs show up across almost every part of a business. Here are common examples you'll recognise as an Australian small business owner:

• Inventory and raw materials that go into the products and services you offer
• Packaging and shipping of those goods, including your cost of goods sold
• Transaction fees for accepting payments by card, digital wallet, and direct debit
• Contractors and casual staff you hire during busy periods
• Marketing, which rises and falls depending on when you run campaigns
• Sales travel, which increases when your reps go on the road
• Commissions and referral bonuses paid on sales

How to calculate variable costs

Working out your variable costs is straightforward once you know your cost per unit. Use this formula:

Total variable cost = variable cost per unit × number of units

Say you make candles, and each candle costs you $8 in wax, wicks, and packaging. If you produce 500 candles in a month, your total variable cost is $8 × 500, which comes to $4,000.

The variable cost per unit is simply the cost tied to making one item. Marginal cost is closely related: it's the cost of producing one more unit, which helps you decide whether extra output is worth it.

Variable costs vs fixed costs

Every cost in your business is either variable or fixed, and it can't be both. Knowing which is which helps you plan with more confidence.

Fixed costs stay the same no matter how active your business is. They cover things like rent, insurance, and permanent wages and salaries. Here's how the two compare:

• Variable costs change with output, so they grow as you sell more and shrink when you sell less
• Fixed costs stay flat over a period, whether you make 10 sales or 10,000
• Variable costs are harder to predict, while fixed costs are easy to budget in advance
• Both feed into your operating expenses and your overall profitability

What are stepped (semi-variable) costs?

Some costs sit between variable and fixed, which is where stepped costs come in. They are also called semi-variable or mixed costs.

Many variable costs rise in direct proportion with activity. Inventory costs, for example, often climb in perfect alignment with sales. In other cases the relationship isn't so linear.

A busy business might hire a new employee who can make another 200 products. The wage cost jumps in one large step, but it opens the door to another 200 sales. Costs that move in jumps like this are known as stepped costs.

Why variable costs matter

Variable costs shift from week to week and month to month, depending on what your business is doing. Because they're harder to predict than fixed costs, understanding them is central to good financial planning.

Tracking your variable costs helps you set accurate budgets and forecast your cash flow needs. It also shows you your break-even point, the moment your sales cover all your costs.

Keeping variable costs in check protects your gross profit, so you keep more of every sale as your revenue grows.

How to reduce variable costs

Trimming variable costs lifts your margin on every unit you sell. Try these practical tactics for your small business:

• Negotiate better rates with suppliers or buy materials in bulk
• Compare payment providers to lower your card and transaction fees
• Reduce waste in production so more of your raw materials become saleable stock
• Review contractor and casual hours to match them closely to demand
• Track spending in real time so you can spot rising costs early

Track your variable costs with Xero

Variable costs move constantly, so seeing them clearly is the first step to managing them well. Xero brings your income and spending together in one place, giving you real-time visibility over the costs that shift with your sales.

When you can watch your numbers as they change, budgeting, forecasting, and pricing all get easier. Start managing your variable costs with Xero and get one month free.

FAQs on variable costs

Here are answers to some frequently asked questions about variable costs to help you manage your business finances.

What is the difference between fixed and variable costs?

Fixed costs stay the same regardless of your activity, such as rent and insurance. Variable costs rise and fall with your output, such as inventory and transaction fees.

How do you calculate variable cost?

Multiply your variable cost per unit by the number of units you make or sell. For example, $8 per unit across 500 units gives a total variable cost of $4,000.

What is a semi-variable or stepped cost?

A semi-variable or stepped cost has both fixed and variable elements, so it stays flat until activity crosses a threshold. It then jumps in a step, such as hiring an extra staff member to lift production.

How do variable costs affect your break-even point?

Your break-even point is where sales cover all your costs, and higher variable costs per unit push it further out. Lowering variable costs means you break even on fewer sales.

What are some ways to reduce variable costs?

You can negotiate supplier rates, buy in bulk, cut production waste, and lower payment processing fees. Matching casual and contractor hours to demand also helps keep these costs down.