ARR Calculator — MRR to ARR, NRR & Growth Projection

How to use

1. Choose MRR or ARR and enter your current figure.
2. Add monthly new-business, expansion and churned MRR.
3. Press Calculate for ARR now, the 12-month run-rate and NRR.
4. Scroll to the glossary if a SaaS term is new to you.

General information only — not medical, financial or legal advice. Figures cross-checked against public official sources (IRS / HMRC / NHS / WHO guidance); content last reviewed September 2026. For decisions that matter, confirm with a licensed professional in your country.

About this tool

Boards speak ARR, so this tool translates. Enter MRR — or toggle to ARR and it back-solves monthly — then add your new-business, expansion and churned MRR per month. You get ARR right now, a simple 12-month run-rate projection that assumes today's flows continue, Net Revenue Retention computed as (starting MRR + expansion − churn) ÷ starting MRR, and both monthly and annualized growth rates. When churn looks off, the tool says so instead of printing a nonsense number. The SaaS glossary below the form spells out MRR, ARR, NRR, expansion and churn in plain English so the whole team reads the same numbers the same way. It is deliberately simple math — no cohorts, no seasonality — which makes it ideal for quick planning, investor-update drafts and sanity-checking what your billing dashboard reports.

FAQ

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