Variable costs

Definition

Variable costs are expenses that change in proportion to output or sales — raw materials, stock purchases, packaging, sales commission. They rise as you sell more and fall as you sell less.

In plain terms

They're the costs of each sale itself. Unlike fixed costs, they flex naturally with how busy you are.

Why it matters for your company

Variable costs determine your contribution margin per sale, which drives profitability and pricing. See fixed costs.

In practice

For a UK limited company, variable costs show up whenever a sale is made, not before. A retailer restocking shelves, a caterer buying ingredients for a booking, or a sales team earning commission on completed orders are all incurring costs that track activity directly. Quiet trading periods bring these costs down almost automatically, because there is simply less output generating them.

This is what separates variable costs from the rent, insurance and core staffing that a company must cover regardless of how busy it is. A director reviewing monthly management accounts can usually spot variable costs by asking whether the expense would still exist if no sales had been made that month — if the answer is no, it is variable.

How lenders read it

When a lender looks at a company's cost base, the split between fixed and variable costs helps explain how resilient the business is to a slow patch. A company where most costs are variable can scale back spending quickly if sales dip, which tends to support steadier cash flow through quieter periods.

Lenders also look at how variable costs are recorded — consistent, well-categorised management accounts make it easier to see the underlying trend, whereas costs that drift between fixed and variable categories from month to month can make a company's numbers harder to interpret. See fixed costs for the counterpart to this picture.