MRR / ARR growth forecaster
Project your SaaS recurring revenue forward from new MRR, expansion, and churn - with net revenue retention and a month-by-month trajectory.
Forecast your MRR & ARR
Project your recurring revenue forward, accounting for new sales, expansion, and churn.
Your current monthly recurring revenue
Net-new MRR from new customers each month
Upsell/expansion as % of MRR
Revenue churn as % of MRR
Fill in all fields to see your projection.
Quick answer: An MRR/ARR forecaster projects your recurring revenue forward. Each month it adds new MRR and expansion, subtracts churn and contraction, and carries the result forward. ARR run-rate is your ending MRR multiplied by 12. This tool also computes net revenue retention (NRR) and gross revenue retention (GRR).
How the forecast works
For each month: ending MRR = starting MRR + new MRR + expansion - churn. The ending MRR becomes next month's starting point, so growth compounds. We annualize your final MRR into an ARR run-rate and report retention metrics so you can see whether growth is healthy or propped up by new sales alone.
Key metrics explained
| Metric | What it means | Healthy benchmark |
|---|---|---|
| NRR | Net revenue retention (with expansion) | 100%+ (110%+ is strong) |
| GRR | Gross revenue retention (before expansion) | 90%+ (SMB), 95%+ (enterprise) |
| ARR run-rate | Ending MRR x 12 | Grows month over month |
| MoM growth | Compounded monthly growth | 10-15% at seed stage |
A caveat on forecasts
This model assumes constant monthly rates. Real SaaS revenue is lumpier - enterprise renewals cluster, seasonality shifts demand, and growth rarely holds perfectly steady. Use the forecast to pressure-test a plan and align on targets, then validate against your actual cohort and retention data.
How to use this forecaster (step by step)
- Enter your starting MRR as the baseline.
- Set monthly movements - new MRR, expansion, and churn/contraction - plus the forecast horizon.
- Read the trajectory month by month and the ending ARR run-rate.
- Check NRR and GRR to confirm growth is durable, not just new-sales-driven.
- Stress-test by adjusting churn and expansion for best- and worst-case scenarios.
The three levers of recurring revenue growth
Every recurring-revenue model is driven by three forces. Understanding their relative impact is what makes a forecast useful:
- New MRR - revenue from new customers. It's the most visible lever but also the most expensive to grow, since it depends on continuous acquisition.
- Expansion MRR - upsells, seat growth, and usage increases from existing customers. The cheapest, most durable growth, and the foundation of net negative churn.
- Churn & contraction - the leak. Because it compounds against your whole base, a small reduction in churn often beats a large increase in new sales over a 12-month horizon.
A common realization from this model: a business can grow new sales aggressively yet stall, because churn is eating the base. Forecasting all three together shows where to focus.
Common forecasting mistakes
- Ignoring churn. A forecast that only adds new MRR overstates growth dramatically.
- Confusing ARR run-rate with booked ARR. Run-rate annualizes one month; it's a projection, not contracted revenue.
- Assuming rates hold forever. Growth rates almost always decay as the base gets larger - model that.
- Forgetting expansion. Leaving out upsells understates the value of your existing base.
Frequently asked questions
- What's the difference between MRR, ARR, and run-rate?
- MRR is monthly recurring revenue, ARR is annual, and ARR run-rate annualizes current MRR (x12) to project a full year if this month repeated.
- What is net revenue retention?
- How much recurring revenue you keep and grow from existing customers including expansion, minus churn. Above 100% means the base grows without new customers.
- What's a good monthly growth rate?
- Seed-stage often targets 10-15% MoM; later stages grow slower in percentage but on a larger base. T2D3 is a common venture benchmark.
- How accurate is this forecast?
- It's directional - it assumes constant rates. Real revenue is lumpier. Use it to plan, then validate with cohort data.
- Is this calculator free?
- Yes - free, no signup, fully client-side.
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