How to Build a SaaS Revenue Forecast

A useful SaaS forecast begins with a few inputs that the team can explain. The basic components are starting MRR, new MRR, expansion MRR, contraction MRR, churned MRR, pricing assumptions, and forecast period. More advanced models add acquisition channels, sales capacity, payment failures, renewals, implementation fees, and customer segments.

The danger is building a model that looks precise but hides weak assumptions. A forecast should make assumptions visible. If growth depends on doubling paid acquisition, the model should say so. If churn improves because onboarding gets better, the model should show how much improvement is required.

A simple model starts each month with starting MRR. It adds new recurring revenue, adds expansion revenue, subtracts downgrades, subtracts churn, and produces ending MRR. Ending MRR then becomes the next month starting MRR. ARR is ending MRR x 12.

Example: a company starts with $15,000 MRR, expects $2,000 new MRR per month, $500 expansion MRR, $250 contraction MRR, and $600 churned MRR. Ending MRR for the first month is $16,650. The next month starts from $16,650. The arithmetic is simple, but repeating it month by month shows whether growth is actually compounding.

Build at least three scenarios. The conservative scenario should reflect slower acquisition and higher churn than you want. The base scenario should reflect what the current business can plausibly execute. The aggressive scenario should show what happens if the team improves conversion, pricing, expansion, and retention.

Scenario planning is useful because SaaS forecasts are sensitive. A one-point change in monthly churn can materially change a multi-year projection. A small improvement in activation can increase expansion later. The goal is not to pick the most exciting curve. The goal is to identify the assumptions that deserve management attention.

Aura Revenue intentionally uses four public inputs: starting MRR, monthly growth, monthly churn, and time horizon. That makes it fast for founders, creators, and small software teams to understand the relationship between growth and retention before building a more detailed spreadsheet.

Use the calculator first to test the shape of the revenue curve. Then use the free SaaS revenue forecast template to build a month-by-month operating version with new MRR, expansion MRR, churned MRR, and ARR columns. The methodology page explains what the calculator includes and what it leaves out.

A forecast is stronger when each number ties to an operating driver. New MRR can come from website conversion, sales demos, partner referrals, or outbound pipeline. Expansion MRR can come from seat growth, usage, add-ons, or tier upgrades. Churned MRR can come from customer fit, onboarding gaps, budget cuts, or competitive loss.

Instead of entering a growth rate because it looks good, write the mechanism beside it. For example: 60 trials per month, 12% paid conversion, $180 average starting plan, and 10% of accounts upgrading after month three. That forecast can be challenged and improved. A plain 8% monthly growth assumption cannot.

Keep the first model simple, then add detail where decisions depend on it. If hiring a salesperson depends on sales capacity, add pipeline and quota assumptions. If cash timing matters, add annual prepayments and monthly expenses. If retention is the main risk, add cohorts.

• Tie new MRR to acquisition volume and conversion.
• Tie expansion MRR to customer usage or plan movement.
• Tie churn to observed cohorts and cancellation patterns.
• Document every assumption so future updates are easier.

Update the model every month after the revenue close. Replace assumptions with actual starting MRR, new MRR, expansion MRR, contraction MRR, and churned MRR. Then adjust future assumptions only where the business has new evidence.

Look for variance, not just totals. If ending MRR matches the forecast but new MRR is lower and churn is also lower, the business performed differently than expected. That matters because the next month may depend on a different operating lever.

Aura Revenue is useful for quick scenario work between full spreadsheet updates. Use it when you want to answer a focused question: what happens if churn improves one point, if growth slows, or if the forecast period extends from 24 to 60 months?

Keep one tab or page for assumptions. List each input, owner, source, and last update. If monthly growth comes from paid acquisition, link it to spend, conversion rate, and average starting subscription. If churn improves, link it to cohort evidence or a retention project. If pricing changes, record the date and affected customer segment.

Separate actuals from projections. Actual months should lock after close. Future months should remain editable and clearly marked. This prevents accidental rewriting of history when the team wants the forecast to look cleaner.

Finally, keep the model readable. A founder should be able to explain the forecast in five minutes. If the model is too complex to explain, it will be too complex to manage.

After you read this guide, open the Aura Revenue calculator and change one assumption at a time. Keep starting MRR fixed, then adjust growth, churn, or the forecast period to see which input changes the outcome most. That exercise turns the concept into a planning habit.

For a deeper model, copy the SaaS revenue forecast template and split the monthly movement into new MRR, expansion MRR, contraction MRR, churned MRR, ending MRR, and ARR run rate. The calculator is best for fast scenario thinking. The template is better when you need operating detail.