#959 · Startup Tool

Series A Retention Calculator

Measure customer retention, gross revenue retention, and net revenue retention for a Series A SaaS company. Use it to evaluate whether existing customers can support efficient ARR growth.

Calculator

Retention inputs
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How to use this calculator

  • Enter customers at the start of the period.
  • Enter customers remaining at the end of the period, excluding new customers where possible.
  • Add starting ARR.
  • Enter expansion ARR from retained accounts.

What the result means

Strong retention shows product value and reduces dependence on new acquisition. Net revenue retention above 100% means expansion offsets lost revenue.

Customer Retention = Ending Customers ÷ Starting Customers × 100. Estimated NRR = Customer Retention + Expansion ARR ÷ Starting ARR × 100.

For exact NRR, include lost ARR and contraction ARR. This version estimates retention health from customer retention and expansion ARR.

Example calculation

If 950 of 1,000 customers remain and expansion ARR is $900,000 on $6M starting ARR, retention is 95% and estimated NRR is 110%.

Tips for better results

  • Track retention by cohort and segment.
  • Improve activation and customer success motions.
  • Increase expansion through seats, usage, and plan upgrades.
  • Separate gross retention from net retention.

FAQ

What is a good net revenue retention rate for Series A SaaS?

Net revenue retention above 110% is strong for many B2B SaaS companies, while 120% or more can support premium growth narratives.

How do I calculate gross revenue retention?

Gross revenue retention measures retained revenue before expansion and excludes upsell or cross-sell revenue.

Why does net revenue retention matter to investors?

NRR shows whether existing customers can grow revenue over time, reducing pressure on new customer acquisition.

What is the difference between GRR and NRR?

GRR excludes expansion revenue, while NRR includes expansion revenue after churn and contraction.

How can a startup improve retention before Series B?

Improve onboarding, customer success coverage, product adoption, account expansion, and churn prediction workflows.

Decision metrics

MetricMeaning
Customer RetentionShare of starting customers retained.
Estimated NRRRetention plus expansion contribution.
Expansion CoverageExpansion ARR as share of starting ARR.
Retention HealthInvestor-facing retention score.

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