Burn rate is the rate at which a business consumes cash over a specified period, usually expressed as a monthly amount, and the term is especially common when discussing startups and other cash-funded companies. It indicates how quickly available cash is being used to finance operations before the business generates sufficient cash from its activities or obtains additional funding. Burn rate is not necessarily the same as accounting loss because cash consumption and accounting expenses differ.
The concept is particularly useful for businesses that are investing heavily in product development, hiring, marketing, infrastructure or expansion before reaching positive operating cash flow. A company may therefore have a substantial burn rate even when its management deliberately accepts short-term cash losses to pursue growth or development objectives.
Gross burn and net burn are commonly distinguished. Gross burn refers broadly to the total amount of cash spent during a period, whereas net burn measures the net reduction in cash after considering cash generated from operations or other inflows, depending on the definition being used.
For example, a company spending £150,000 in a month and receiving £50,000 of operating cash inflows might have gross cash expenditure of £150,000 and net cash consumption of £100,000, subject to the precise accounting and management definitions used. Because terminology varies between companies and investors, financial reports should specify exactly how burn is calculated. A simple monthly average can also conceal significant fluctuations caused by annual insurance payments, tax obligations, equipment purchases, bonuses or other irregular transactions.
Burn rate is closely connected to business runway. Runway estimates how long a company can continue operating at its current rate of cash consumption before available cash is exhausted. A simplified calculation divides available cash by monthly net burn. If a business has £600,000 of usable cash and an average net burn of £100,000 per month, its theoretical runway is six months, assuming burn remains constant and no additional cash becomes available. In practice, management should account for committed obligations, minimum cash requirements, seasonality, expected revenue changes, financing timing and potential changes in expenditure. A runway calculation is therefore a planning approximation rather than a guaranteed operating lifetime.
Burn rate can change substantially as a business moves through different stages. A company may initially have high expenditure on product development and hiring, then increase spending further during a customer-acquisition campaign, and later reduce burn as revenue grows or investment priorities change. Management may deliberately increase burn to accelerate expansion, but doing so reduces the time available to reach milestones before additional financing or revenue becomes necessary. Reducing burn can extend runway, but indiscriminate cost cutting may also reduce product quality, sales capacity or the capabilities needed to generate future revenue. The appropriate burn rate therefore depends on the business model, available capital, growth strategy, expected margins and specific objectives.
Burn-rate analysis is especially important for venture-funded startups, but the concept is relevant to any cash-consuming organisation. A company can monitor monthly cash expenditure, operating cash inflows, working-capital movements and exceptional payments to understand its actual cash consumption. Management can then create base, downside and upside scenarios. A downside scenario might assume slower sales, delayed customer payments or higher costs, while an upside scenario might incorporate faster revenue growth. Such scenarios can show how quickly the burn rate could change and whether existing liquidity remains adequate under different circumstances.
Burn rate should not be confused with expenses alone. An accounting expense may not involve an immediate cash payment, while a cash payment may relate to an asset that is not fully expensed immediately under accounting rules. Capital expenditure is a common example: purchasing machinery can produce a substantial cash outflow while the accounting cost is recognised through depreciation over time. Changes in accounts receivable, inventory and accounts payable can also affect cash consumption. For this reason, a business assessing its burn should normally examine actual cash-flow information rather than simply subtracting reported accounting profit from revenue.
High burn can sometimes be intentional and economically rational, particularly when a company is investing in capabilities expected to produce future returns. However, burn becomes dangerous when spending is disconnected from measurable progress, when gross margins cannot support the eventual operating structure, or when financing assumptions prove unreliable. Useful management measures include burn against budget, burn by functional area, changes in burn over time, cash conversion, customer acquisition economics and progress against strategic milestones. Investors and boards may also examine whether spending is producing product development, customer growth, revenue, retention or other evidence of increasing enterprise value.
Burn rate is fundamentally a liquidity and strategic-planning measure. It answers the question of how rapidly cash resources are being consumed and therefore helps determine how urgently a company needs revenue growth, cost reduction, financing or another source of liquidity. The figure is most meaningful when paired with cash reserves, runway, revenue, gross margin, working capital and planned expenditure. A monthly burn number without its calculation method or surrounding financial context can be misleading. Sound cash management therefore tracks both the amount of cash being consumed and the reasons for that consumption, distinguishing productive investment from avoidable expenditure and modelling how changes in revenue or costs will affect future liquidity.
