Existing-customer revenue growth.

Net Revenue Retention (NRR) measures MRR from existing customers including churn, contraction, and expansion. Above 100% means the existing base grows even without new sales - the holy grail of SaaS. Best-in-class hits 120-140% NRR; 100-110% is healthy; below 100% means the business needs net new sales just to stand still.

100k starting MRR, 3k churn, 2k contraction, 8k expansion = net change +3k. NRR = 103%. Existing customers collectively pay 3% more at period end than they did at start. Over a year at that rate, the existing base alone adds 36k/year ARR before new sales count.

NRR above 120% is a compounding machine. A business with 120% NRR and zero new sales grows 20% per year from existing customers alone. Add even modest new sales on top and growth compounds to 40-60% annually. This is why investors value NRR so highly - it's the predictor of long-term growth sustainability.

Run it with sensible defaults

Using starting mrr of 100,000, churned mrr of 3,000, contraction mrr of 2,000, expansion mrr of 8,000, the calculation works out to 103.00%. Nudge the inputs toward your own situation and the output recalculates instantly. The defaults are meant as a starting point, not a recommendation.

The levers in this calculation

The inputs — Starting MRR, Churned MRR, Contraction MRR, and Expansion MRR — do not pull with equal force. Not every input has equal weight. Flip one at a time toward extreme values to feel which ones move the needle most for your situation.

How the math works

NRR = (starting + expansion - churn - contraction) ÷ starting × 100. No cap - can exceed 100%. The working is transparent — you can verify every step yourself in the formula section below. No black box, no opaque "proprietary model".

What to do with a low result

A disappointing result is information, not a judgement. Pick the single input that dragged the figure down most and focus the next quarter on that one factor. Breadth-first improvement rarely works; depth-first on the worst input usually does.

What this doesn't capture

The score is a composite of the inputs you provide. Life context — job security, family obligations, health, housing — doesn't appear in the math but shapes the real picture. Use the number as a prompt, not a verdict.