NRR Calculator: Net and Gross Revenue Retention

The NRR and GRR formulas

NRR = (Starting MRR + Expansion − Contraction − Churn) ÷ Starting MRRIncludes expansion, can exceed 100%

GRR = (Starting MRR − Contraction − Churn) ÷ Starting MRRExpansion excluded, never above 100%

Both use the same base: the customers who were paying on the first day of the period. Revenue from customers who signed up during the period is left out of both, otherwise new sales would look like retention. The only difference is the expansion term, so NRR minus GRR always equals expansion as a share of starting revenue.

The calculator works on MRR or ARR. Use the same unit for all four inputs.

Monthly to annual

Annual NRR ≈ (Monthly NRR)¹² = (Quarterly NRR)⁴Compound, do not multiply by 12

Benchmarks such as Benchmarkit and SaaS Capital are annual. SaaS Capital defines it as December MRR from customers who were already customers a year earlier, divided by total MRR a year earlier. So a monthly result has to be converted before you compare it. Compounding is an approximation: it assumes every month looks like the one you entered. It also treats a downgrade that a customer reverses later in the year as a loss, so compounded monthly GRR usually comes out lower than a true 12-month GRR. When you have a full year of data, measure the cohort directly: revenue today from last year's customers, divided by their revenue a year ago.

Worked example

Illustrative numbers, the calculator's defaults. A SaaS company starts the month with $80,000 MRR from existing customers. During the month those customers add $2,000 in upgrades, downgrade by $400, and $1,200 of MRR cancels.

• Monthly NRR = $80,400 ÷ $80,000 = 100.5%. Net expansion is +$400.
• Monthly GRR = ($80,000 − $400 − $1,200) ÷ $80,000 = $78,400 ÷ $80,000 = 98.0%.
• Annual equivalents (compounded, approximate): NRR 1.005¹² = 106.2%; GRR 0.98¹² = 78.5%.
• Against Benchmarkit 2026 (private B2B SaaS, CY-25): NRR 106.2% is 4.2 points above the 102% median and below the 110% top quartile. GRR 78.5% is 5.5 points below the 84% median and just above the 76% bottom quartile.
• To reach 110% annual NRR with the same losses, monthly expansion would need to be about $2,238 instead of $2,000 (80,000 × (1.1^1/12 − 1) + $1,600).

The point of the example: a monthly NRR of 100.5% looks flat and safe, and the annual NRR is above the median. But the base is losing 2% of its revenue every month before expansion, which compounds to losing about a fifth of it in a year. Expansion is covering a leak. If the upgrades slow down, NRR falls below 100% within a month or two.

The calculator gives you one period at a time. In Adlega, expansion, contraction and churn are drivers in a 36-month SaaS model, so a change to any of them flows through to MRR, ARR, burn and runway, and you can compare scenarios side by side. The AI CFO explains how each number was calculated.