SaaS Quick Ratio Calculator

The underlying calculation

The quick ratio is (new MRR + expansion MRR) ÷ (churned MRR + contraction MRR). It measures how much a business gains for every dollar it loses.

A ratio of 1 means growth exactly offsets losses. Above 4 is the conventional marker of efficient growth; below 2 suggests the business is working hard to stand still.

It condenses the four MRR components into a single efficiency figure that growth rate alone cannot express.

Worked through

($6,200 + $2,200) ÷ ($4,060 + $1,740) = $8,400 ÷ $5,800 = 1.45.

The business adds $1.45 for every dollar lost, so 69% of its gross additions go to replacing attrition and 31% to actual growth.

Halving churn and contraction gives $8,400 ÷ $2,900 = 2.90, and net new MRR rises from $2,600 to $5,500 with no change in acquisition.

Doubling new business instead gives ($12,400 + $2,200) ÷ $5,800 = 2.52 and net new of $8,800, more absolute growth, at the cost of doubling the acquisition spend.

Where it goes wrong

The ratio is volatile at small scale, since a single large account churning can move it substantially in a month. It is best read as a trailing three-month figure.

It also treats a dollar of new business as equivalent to a dollar of expansion, when expansion is far cheaper to obtain and generally more durable.

Making it useful

Track it quarterly rather than monthly, and alongside net new MRR. The ratio describes efficiency and the absolute figure describes scale, and a business needs both.

Then use it to choose between growth levers. A low ratio means retention work will produce more than acquisition work, and the arithmetic above shows by how much.

Why retention beats acquisition at low ratios

When the ratio is near 1, most acquisition is replacing losses rather than adding. Every dollar spent on retention improvement therefore does double duty: it reduces the denominator and it makes future acquisition compound rather than substitute.

At high ratios the reverse holds, a business retaining almost everything gains more from acquiring faster, since there is little leakage left to fix.

That makes the ratio a genuine prioritisation tool rather than a scorecard. Businesses below 2 should be working on churn regardless of what the growth targets say, and the ones that instead push acquisition harder tend to find their growth rate flat while spend rises.

Calculating it separately for new business and for the installed base identifies whether the efficiency problem sits in acquisition quality or in retention, which the blended figure cannot.

A business with a strong ratio on mature cohorts and a weak one overall has an onboarding problem rather than a product one.

Using a trailing three-month window rather than a single month removes most of the volatility that makes the ratio hard to read at smaller scale.

Comparing the ratio before and after a pricing change is a clean way to see whether the change improved the business or merely moved revenue between components.

The ratio is most informative early, when a business is small enough that a handful of accounts move it. At that scale it swings violently month to month and a single quarter tells you very little. Reading it as a rolling three or six month figure smooths the noise without hiding a genuine deterioration, which is what the metric exists to catch.