Substack Paid Newsletter Revenue & Churn Forecaster

Model free-to-paid subscriber conversion, annual vs. monthly tier ratio, platform fees, and forecast recurring MRR/ARR over 12 months.

Paid Substack newsletter income: net MRR and 12-month projection

Gross MRR = monthly subscribers × monthly price + annual subscribers × annual price ÷ 12, where paid subscribers = free list × conversion rate. The tool then deducts the Substack fee (10% by default) and Stripe fees (2.9%). With 8,500 subscribers, 3.5% conversion and a price of 8 per month or 75 per year, net MRR comes to about 1,781.

Tool formulas

  • Paid subscribers = round(free list × conversion); annual subscribers = round(paid × annual share); the rest pay monthly.
  • Gross MRR = monthly × monthly price + annual × annual price ÷ 12; ARR = MRR × 12.
  • Net = gross × (1 − (platform fee + Stripe fees) ÷ 100).
  • Projection: the free list grows each month at the rate entered; new sign-ups convert at the conversion rate, and the paid base loses the churn rate entered every month (3% by default).

Example (default values)

8,500 subscribers × 3.5% = 298 paid, of whom 194 annual (65%) and 104 monthly. Gross MRR: 104 × 8 + 194 × 75 ÷ 12 = 832 + 1,212.50 = 2,044.50. Fees: 10% + 2.9% = 12.9%, giving a net MRR of 1,780.76 and a net ARR of 21,369. With 5% monthly growth, the list reaches 15,265 subscribers in month 12, i.e. 412 paid and 2,463 net MRR with 3% monthly churn (535 paid without churn).

Limits

  • Churn is a single monthly rate, also applied to annual subscribers, who in practice can only leave when their subscription renews.
  • Stripe's fixed per-transaction fee ($0.30 per payment in the US) and recurring billing fees are not calculated; on low prices they add several percentage points.
  • Annual revenue is spread over 12 months although annual subscribers pay once.

Indicative projection, not financial advice.

Sources and dates: the Substack FAQ on paid subscriptions (article dated 24/11/2022, still online) states a 10% fee and quotes Stripe fees of 2.9% + $0.30 per transaction, plus a 0.5% recurring billing fee. Stripe rates vary with the card's country (checked on 14/10/2026).

Frequently Asked Questions

How much does Substack take?

Substack takes 10% of subscription revenue, plus Stripe fees (2.9% + $0.30 per transaction and a 0.5% recurring billing fee according to its FAQ). The tool uses 10% + 2.9% by default, i.e. 12.9%.

What free-to-paid conversion rate should I expect?

The tool starts from 3.5% by default, an editable assumption. With 8,500 subscribers that gives 298 paid; each extra conversion point adds 85 paid subscribers.

How does the tool handle annual plans?

The annual price is divided by 12 to count in MRR: 194 subscribers at 75 per year count for 1,212.50 per month. In cash terms, they pay once a year.

Is churn taken into account?

Yes. The monthly churn rate (3% by default, editable) is removed from the paid base every month, and only new sign-ups convert. With the default values, month 12 has 412 paid subscribers and 2,463 net MRR, against 535 paid without churn.

Is this tool really free?

Yes, all tools on Kristools are 100% free and accessible without registration.

Is my data protected?

Yes. All processing is performed directly and securely inside your browser. No personal data is sent to our servers.