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 semi-variable costs (stepped costs)?
• Why variable costs matter
• Track your variable costs with Xero
• FAQs on variable costs
• Related terms
• Learn more about variable costs

Key takeaways

• A variable cost goes up and down with your business activity, so it rises when you're busy and falls when you're quiet.
• You work out your total variable cost by multiplying the variable cost per unit by the number of units you produce.
• Variable costs are the opposite of fixed costs, which stay the same no matter how much you sell.
• Tracking your variable costs helps you set accurate budgets and predict your cash flow needs.

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 climbs, which makes variable costs the opposite of fixed costs.

Many variable costs, such as inventory and freight, rise in line with the number of sales you're making. Others don't sync up so neatly: spending on marketing, trade shows, and sales travel might be intended to drive sales, but it won't always match them perfectly.

Examples of variable costs

Variable costs show up across almost every part of a business, and most of them shift with how much you're selling. If you want a wider picture of where your money goes, it helps to look at your full range of small business expenses alongside the common examples below.

• Inventory and raw materials that go into the products and services you offer
• Packaging and shipping for those goods
• Transaction fees for accepting payments by card, digital wallet, and direct debit
• Contractors you hire during busy periods
• Marketing that goes up and down depending on when you run campaigns
• Sales travel that increases when 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. Getting this number right also feeds into other planning tools, like the break-even point formula, so it's worth taking the time to get it accurate.

1. Add up every variable expense that goes into making one unit, such as materials, packaging, and any per-sale fees, to get your variable cost per unit.
2. Count the number of units you produced over the period you're measuring.
3. Multiply your variable cost per unit by the number of units to get your total variable cost.

Say you run a bakery and each cupcake costs $2 in ingredients and packaging. If you make 500 cupcakes, your total variable cost is $2 multiplied by 500, which comes to $1,000.

Variable costs vs fixed costs

A cost is either variable or fixed, and it can't be both. The simplest way to tell them apart is to ask whether the expense changes when your sales change.

Fixed costs stay the same no matter how active your business is. They often sit alongside your overhead costs, and you can read more about a single fixed cost to see how it behaves over time.

• Rent for your premises or storage space
• Utilities such as heating, water, and power
• Insurance premiums for your business
• Permanent wages and salaries for your core team

What are semi-variable costs (stepped costs)?

Some costs sit between the two categories, moving in jumps rather than smoothly with each sale. These are known as semi-variable costs, or stepped costs.

Say a busy company hires a new employee who can make another 200 products. The wage cost jumps significantly, but it opens the door to another 200 sales. Costs that shift in these larger steps, rather than rising with every single unit, are what accountants call semi-variable costs.

Why variable costs matter

Variable costs change from week to week and month to month, depending on what your business is doing. That makes them harder to budget for than fixed costs, so keeping an eye on them pays off.

When you understand your variable costs, you can set accurate budgets and predict your cash flow needs with more confidence. For more on planning ahead, see this guide to managing cash flow.

Track your variable costs with Xero

Because variable costs shift with your activity, they're easy to lose track of when you're busy running the business. Xero helps you keep track of these costs in one place and makes it easier to see how they change over time.

That means fewer surprises at the end of the month and a clearer view of your spending, so you always know where your money is going. Get one month free when you sign up.

FAQs on variable costs

Here are answers to frequently asked questions about variable costs.

Is marginal cost the same as a variable cost?

No, they're related but not identical. Marginal cost is the cost of producing one more unit, while variable cost covers the total that changes with your output.

Are wages a variable cost?

It depends on the role. Permanent salaries are usually a fixed cost, while contractor pay, overtime, and sales commissions tend to be variable.

What is the formula for total variable cost?

Total variable cost equals your variable cost per unit multiplied by the number of units you produce. So 500 units at $2 each gives a total variable cost of $1,000.

How do variable costs affect profitability?

Lower variable costs leave you with more profit on each sale you make. Watching them closely helps you price your products well and protect your margins.

Related terms

• Expense
• Fixed cost
• Overhead
• Gross profit
• Break-even point
• Cost of goods sold (COGS)

Learn more about variable costs

• Stay on top of your business costs
• Small business expenses
• Managing cash flow
• Business cost saving ideas
• How to track business expenses