Variable cost

Published Friday 24 July 2026

Table of contents

• What is a variable cost?
• Examples of variable costs
• The variable cost formula and how to calculate it
• Why variable costs matter
• How variable costs differ from fixed costs
• What are stepped costs?
• Track your variable costs with Xero
• FAQs on variable costs
• Related Terms
• Learn more about variable costs

Key takeaways

• A variable cost is an expense that rises and falls with how much your business produces or sells.
• Variable costs are the opposite of fixed costs, which stay the same no matter how busy you are.
• You work out total variable cost by multiplying the number of units by the variable cost per unit.
• Tracking variable costs helps you protect profit on each sale, plan cash flow and find 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. It’s the opposite of a fixed cost, which stays the same whether you’re busy or quiet.

When you sell more, variable costs like inventory and freight tend to rise with you; when sales slow, they fall again. Some costs behave in a looser way, though. Spending on marketing, trade shows and sales travel is tied to activity, but it doesn’t always sync perfectly with each sale you make.

Examples of variable costs

Variable costs show up across day-to-day trading, and they shift as your volume changes. Here are common examples you’ll recognise in a small business:

• Inventory and raw materials
• Packaging and shipping
• Transaction fees for card, digital wallet and direct debit payments
• Contractors hired during busy times
• Marketing that rises and falls with campaigns
• Sales travel
• Commissions and referral bonuses on sales

The variable cost formula and how to calculate it

Working out your variable cost is straightforward once you know your output and your cost per unit. Follow these 3 steps:

1. Count the number of units you produced or sold in the period.
2. Find your variable cost per unit, which is total variable costs divided by the number of units.
3. Multiply the quantity of units by the variable cost per unit to get your total variable cost.

Here’s a quick example. A bakery makes 500 cakes at a variable cost of $4 each, so its total variable cost is 500 × $4, which comes to $2,000.

Why variable costs matter

Variable costs sit at the heart of everyday budgeting and cash flow, because they move with your trading and shape how much cash you need on hand. When you can see them clearly, you can plan spending around busy and quiet periods.

They also affect the profit you make on each sale, and they help you work out your break-even point, the level of sales where your income covers your costs.

How variable costs differ from fixed costs

Every cost in your business is either variable or fixed, not both. The difference comes down to whether the expense moves with your activity or stays put.

Unlike variable costs, fixed costs stay the same regardless of how much you produce or sell. Rent, utilities, insurance and permanent salaries are common examples, and they usually sit alongside your other operating expenses.

What are stepped costs?

Some costs sit between variable and fixed, and these are known as semi-variable or stepped costs. They hold steady across a range of activity, then jump in a step once you cross a certain point.

Say you hire an employee who lets you make another 200 products and handle another 200 sales. Your wage costs don’t creep up gradually with each extra sale; they jump in one step when you take that person on, then stay level until you need to hire again.

Track your variable costs with Xero

Xero brings your costs together in one place, so you can see what you’re spending as sales rise and fall. With clear reports on income and expenses, you can keep an eye on your margins and spot where your money goes. Get one month free.

FAQs on variable costs

Here are answers to some frequently asked questions about variable costs to help you put the ideas into practice.

What is the variable cost formula?

Multiply the number of units you make or sell by the variable cost per unit. That gives you your total variable cost for the period.

What are examples of variable costs?

Common ones include inventory, packaging, shipping, payment transaction fees and sales commissions. Contractor pay during busy periods often counts too.

Is labour a variable or fixed cost?

It depends on how the work is paid. Permanent salaries are usually fixed, while casual, contractor or commission-based pay tends to be variable.

What is the difference between variable and fixed costs?

Variable costs move with your trading activity, while fixed costs stay the same no matter how much you sell. A single cost is one or the other, not both.

Related Terms

• Fixed cost
• Operating expense
• Expense

Learn more about variable costs

• Cost of sales
• Cost of goods sold
• Overhead costs
• Profitability ratios