Burn rate is the speed at which a company uses cash over a defined period. SaaS startups track it to understand how quickly their cash balance is shrinking and how much time they have to reach important milestones or secure more funding. Burn rate is commonly described as gross burn or net burn, so reports should make the definition clear.
Gross Burn vs. Net Burn
| Measure | Calculation | What it shows |
|---|---|---|
| Gross burn | Total cash operating outflows during the period | How much cash is spent before considering incoming cash |
| Net burn | Cash outflows minus cash inflows during the period | How much the cash balance decreases overall |
Average Monthly Net Burn = Net Cash Used Over the Period ÷ Number of Months
Example: If cash decreases by $450,000 over three months, average monthly net burn is $150,000.
Use cash movement rather than accounting profit alone. Revenue may be recognized before or after cash is collected, and non-cash expenses can affect profit without directly reducing cash in the same period.
How to Estimate Runway
Cash Runway (months) = Available Cash ÷ Average Monthly Net Burn
If a company has $1.8 million in available cash and burns $150,000 per month, the simple estimate is 12 months of runway.
This estimate assumes the burn rate stays constant. Real cash needs can change due to hiring, annual renewals, collection delays, growth, or unexpected costs. Use a cash forecast with scenarios for important decisions.
Why Burn Rate Matters
- Helps leaders plan fundraising and financing needs.
- Shows how quickly operating costs consume available cash.
- Supports decisions about hiring, investment, and discretionary spending.
- Provides an early warning when revenue or collections fall behind plan.
How to Manage Burn Rate
Build a rolling cash forecast
Track expected receipts and payments, including payroll, cloud infrastructure, taxes, debt, and annual contracts. Update the forecast as actual results arrive.
Understand the drivers
Break spending down by category and compare it with the plan. Distinguish deliberate growth investment from waste, delays, or unexpected cost increases.
Improve collection and retention
Timely invoicing, clear payment terms, payment recovery, and customer retention can improve cash position. Revenue growth alone does not guarantee cash arrives on time.
Prioritize spending carefully
Focus on work that supports customer value and sustainable growth. Across-the-board cuts can damage product quality, retention, or the ability to generate revenue.
Plan for uncertainty
Model a base case and downside case, including slower sales, delayed collections, or higher costs. Decide in advance what actions would be taken if runway falls below a threshold.
Common Mistakes
- Confusing burn rate with accounting loss.
- Using a single unusually strong or weak month as the long-term average.
- Ignoring one-time payments or seasonal cash patterns.
- Assuming runway is fixed even when revenue and spending change.
- Waiting until cash is low before changing the plan.
Frequently Asked Questions
Is a high burn rate always bad?
No. A company may spend more to support a deliberate growth phase, but it should understand the expected return and the cash risk. High burn without progress or a credible plan can be dangerous.
What is a safe runway?
There is no universal number. It depends on fundraising conditions, sales cycles, operating risk, and how long it takes to reach the next milestone. Plan for uncertainty rather than relying on a single minimum.
How often should burn rate be reviewed?
Startups often review cash weekly or monthly, depending on volatility. Update the cash forecast whenever a material assumption changes.