Variable cost

Published Friday 24 July 2026

Table of contents

• What is a variable cost?
• Examples of variable costs
• How to calculate variable costs
• Why variable costs matter
• How variable costs differ from fixed costs
• What are stepped costs?
• Manage your variable costs with Xero
• FAQs on variable costs
• Related terms
• Learn more about variable costs

Key takeaways

• Variable costs are expenses that rise and fall with your business activity, unlike fixed costs that stay the same.
• Common examples include inventory, raw materials, packaging, shipping, and sales commissions.
• You can find your total variable cost by multiplying the variable cost per unit by the number of units.
• Tracking variable costs helps you budget, set prices, and protect your cash flow.

What is a variable cost?

Variable costs are expenses that go up and down in line with your business activity, and they’re the opposite of fixed costs. When you make or sell more, your variable costs rise; when activity slows, they fall.

That direct link to output makes variable costs a clear signal of how busy your business is. The more you produce, the more you spend on the inputs that go into each sale.

Examples of variable costs

Variable costs show up across many parts of a business. Common examples include:

• inventory and raw materials
• packaging and shipping
• transaction fees for card, digital wallet and direct debit payments
• contractors hired during busy times
• marketing
• sales travel
• commissions and referral bonuses

How to calculate variable costs

You can work out your total variable cost with a simple formula. Multiply the variable cost per unit by the number of units you make or sell:

• total variable cost = variable cost per unit × number of units

For example, if each unit costs HK$5 in materials and packaging and you make 1,000 units, your total variable cost is HK$5,000. Produce more units and that figure rises in step; produce fewer and it drops.

Why variable costs matter

Tracking variable costs helps you plan ahead and protect your cash flow. Because they move with activity, they show how your spending will change as sales rise or fall.

Knowing your variable costs also makes budgeting more accurate. You can forecast expenses for a busy month, set prices that cover your costs, and spot where to trim spending when things are quiet.

How variable costs differ from fixed costs

Every cost in your business is either variable or fixed. The difference comes down to whether the expense changes with your activity.

Fixed costs stay the same regardless of how much you produce or sell, and rent, utilities, insurance, and permanent wages and salaries are typical examples. Variable costs, by contrast, rise and fall with output.

What are stepped costs?

Some costs don’t fit neatly into either group. A stepped cost stays fixed up to a point, then jumps to a new level as your activity grows.

Say you hire a new employee to keep up with rising orders. Their salary is fixed for a while, but once demand outgrows your team again, you take on another person and your costs step up. Stepped costs behave like fixed costs within a range, then shift when you cross a threshold.

Manage your variable costs with Xero

Understanding variable costs helps you price your products, manage cash flow, and make confident decisions as your business grows. Xero’s accounting software brings your income and expenses together, so you can track costs and see where your money goes. Sign up for Xero and get one month free.

FAQs on variable costs

Here are answers to frequently asked questions about variable costs.

What is the variable cost formula?

The variable cost formula is the variable cost per unit multiplied by the number of units produced or sold. So if each unit costs HK$5 and you make 1,000 units, your total variable cost is HK$5,000.

Is labour a variable cost?

It depends on the type of labour. Wages for staff paid by the hour or by output are usually variable, while permanent salaries are fixed.

Are variable costs the same as direct costs?

Not always, though they often overlap. Direct costs can be traced to a specific product, while variable costs are defined by whether they change with your activity.

What is a stepped cost?

A stepped cost stays fixed within a range of activity, then jumps to a higher level once you pass a threshold. Hiring an extra employee as demand grows is a common example.

Related terms

• Fixed cost
• Expense
• Overhead
• Cost of sales
• Gross profit

Learn more about variable costs

• Overhead cost: meaning, types and how to calculate it
• Cost of sales: what it is, how to calculate and cut
• How to calculate gross profit margin
• More accounting terms