Subscription Revenue Forecast Calculator

Calculator Inputs

Starting Customers

Starting ARPU ($)

New Customers Per Month

New Customer Growth Rate (%)

Monthly Churn Rate (%)

Reactivation Rate (%)

Expansion Revenue Rate (%)

Contraction Revenue Rate (%)

Gross Margin (%)

CAC Per New Customer ($)

Price Increase (%)

Price Increase Month

Annual Prepay Share (%)

Annual Discount (%)

Forecast Months

Example Data Table

Input	Example Value	Meaning
Starting Customers	250	Current active subscribers at forecast start.
Starting ARPU	$79.00	Average recurring revenue per customer monthly.
New Customers Per Month	28	Expected monthly customer acquisition volume.
Monthly Churn Rate	3.2%	Share of customers expected to cancel monthly.
Expansion Revenue Rate	2.5%	Extra revenue from upsells and plan upgrades.
Gross Margin	82%	Percent remaining after direct service costs.

Formula Used

Ending Customers = Starting Customers + New Customers - Churned Customers + Reactivated Customers

Churned Customers = Starting Customers × Monthly Churn Rate

New Customers for Month n = Base New Customers × (1 + Growth Rate)^n-1

Base Recurring Revenue = Ending Customers × ARPU

Revenue After Expansion and Contraction = Base Recurring Revenue + Expansion Revenue - Contraction Revenue

Annual Billing Adjustment = Revenue × [1 - (Annual Prepay Share × Annual Discount)]

ARR = MRR × 12

Gross Profit = (MRR × Gross Margin) - CAC Spend

LTV = (ARPU × Gross Margin) ÷ Monthly Churn Rate

This model helps estimate recurring revenue growth while accounting for churn, pricing changes, expansion, contraction, discounts, and acquisition efficiency.

How to Use This Calculator

Enter your current subscriber count and monthly ARPU.
Add projected new customers and expected acquisition growth.
Set monthly churn and optional reactivation rates.
Include expansion, contraction, annual billing, and discount assumptions.
Enter margin, CAC, and any future price increase.
Choose the number of forecast months.
Click Generate Forecast to see results above the form.
Review the chart, summary metrics, and detailed monthly table.
Download CSV for spreadsheet analysis or print to PDF.

Frequently Asked Questions

1. What does this calculator forecast?

It forecasts subscription revenue across future months using customer counts, churn, new acquisitions, pricing, upsells, annual discounts, and gross margin assumptions.

2. What is ARPU?

ARPU means average revenue per user. It represents the monthly recurring revenue generated by one active customer on average.

3. Why include churn?

Churn directly reduces active subscribers and recurring revenue. Even small churn changes can materially affect long-term forecast outcomes and customer lifetime value.

4. What is expansion revenue?

Expansion revenue is extra recurring income from upgrades, add-ons, seat increases, or customers moving to higher-priced subscription tiers.

5. Why does annual prepay reduce monthly revenue here?

This calculator adjusts monthly recognized value using the discount impact of annual deals. It simplifies billing effects for planning and comparison.

6. What does LTV:CAC show?

LTV:CAC compares customer lifetime value against acquisition cost. Higher ratios usually indicate stronger unit economics and healthier growth efficiency.

7. Can I use this for SaaS planning?

Yes. It works well for SaaS, memberships, digital subscriptions, service retainers, or any recurring revenue business with measurable churn.

8. Does this replace a full finance model?

No. It is a planning calculator, not a complete financial model. Use it for directional forecasting, scenario testing, and quick revenue analysis.