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Revenue Forecast Calculator

A simple revenue forecast for SaaS or subscription businesses. Project the next quarter from current ARR using growth rate, churn, and expansion. The calculator outputs a base case plus optimistic and conservative bookends.

Inputs

Adjust the values. Results update live. The URL updates too — copy it to share your scenario.

Results

Updated live as you change inputs.

Base-case quarter ARR

Current ARR × (1 + new − churn + expansion). The point estimate.

Conservative (80% of base growth)

Assumes growth lands 20% under plan, churn 20% over. Floor for board planning.

Optimistic (120% of base growth)

Assumes growth lands 20% above plan, churn 20% under. Ceiling for board planning.

Net new ARR this quarter

New ARR + expansion − churn. The number that flows into burn multiple.

Embed this calculator on your site — single iframe, no JS dependency.

What this forecast captures (and what it doesn't)

This is a top-down, growth-rate-driven forecast. It captures the four levers that drive ARR change: new ARR, churn, expansion, and time. It does not capture:

  • Seasonality (Q4 enterprise close vs Q1 budget freeze)
  • Cohort retention curves (older cohorts churn differently than recent)
  • Pricing changes mid-quarter
  • Channel-specific dynamics

For a deeper forecast, run a bottom-up pipeline-driven model in parallel and reconcile.

How to use the three scenarios

The base case is the point estimate. The conservative and optimistic bookends model a ±20% miss on each lever. Use the band — not the point — when communicating to a board. "We expect $5.4M next quarter ± $0.4M" beats "We expect $5.4M next quarter" because it sets expectations and leaves room for normal forecasting noise.

Bottom-up reconciliation

If your bottom-up pipeline forecast and this top-down forecast diverge by more than 10%, one of them is wrong. Usually the bottom-up is too optimistic (sales bias) or the top-down assumes growth that doesn't reflect the current pipeline reality.

Stop calculating once. Start watching it live.

Fairview tracks this metric across your real data and tells you when to act — not just what the number is.