Definition
Variable cost is a cost that scales with usage, such as calls, GB-month, or minutes.
Why it matters
Variable costs determine unit economics and margin. If they are underestimated, pricing will not cover cost at scale.
Pricing implications
Usage-based pricing should align with variable costs. If variable costs rise with usage spikes, overage rates should reflect that risk.
Measurement tips
Use blended unit costs from billing data and update them regularly.
Checklist
- Separate variable costs from fixed overhead.
- Track variable cost per unit over time.
- Include vendor pass-through costs.
- Model p50 and p90 usage scenarios.
- Update costs after vendor pricing changes.
- Use variable cost in margin and payback models.
- Validate against invoices quarterly.
- Document cost assumptions in pricing reviews.