Substack / Legacy Newsletter Platform vs Kit (formerly ConvertKit)
Estimate what moving from Substack / Legacy Newsletter Platform to Kit (formerly ConvertKit) costs over 12 to 36 months, including the one-time switch. Then remap your exported CSV headers.
Why teams look at this switch: Losing 10% of paid newsletter revenue to Substack platform fees
Cost calculator
CSV header mapper
Rename exported Substack / Legacy Newsletter Platform column headers to suggested Kit (formerly ConvertKit) column names, for reporting or manual data preparation. Not an official Kit (formerly ConvertKit) import format. It runs in your browser; only headers change.
Renamed headers do not make a file import-ready. Compare the result with Kit (formerly ConvertKit)'s import template and create any custom fields there first. For contact lists, check opt-out and unsubscribe status separately before importing.
| Substack / Legacy Newsletter Platform column | Kit (formerly ConvertKit) column | Field type |
|---|---|---|
| email_address | Suggested | |
| name | first_name | Suggested |
| subscription_type | tags | Suggested |
| created_at | created_at | Suggested |
| stripe_connected | member_status | Consent or status, verify opt-outs |
When moving to Kit (formerly ConvertKit) makes sense
- Your main cost driver is Losing 10% of paid newsletter revenue to Substack platform fees, and your volume is past the break-even point above.
- Your team can finish the CSV import and onboarding within the switching budget you entered.
- You have checked that Kit (formerly ConvertKit)'s plan covers the integrations and compliance rules you need.
When staying on Substack / Legacy Newsletter Platform is the better call
- The one-time migration, re-integration or retraining cost is larger than 12 to 24 months of savings.
- You are inside a multi-year Substack / Legacy Newsletter Platform contract with early-termination fees.
- Your workflow relies on add-ons or features Kit (formerly ConvertKit) does not support yet.
How the result changes with volume
Twelve-month totals at half, default and double volume, using the default pricing model and a $150 switching cost.
| Volume (Paid & Free Subscribers) | Substack / Legacy Newsletter Platform | Kit (formerly ConvertKit) | 12-month difference |
|---|---|---|---|
| 50% volume (7,500) | $238/mo | $70/mo | +$1,866 |
| Default volume (15,000) | $425/mo | $115/mo | +$3,570 |
| 200% volume (30,000) | $800/mo | $205/mo | +$6,990 |
Questions
How is the total cost of Substack / Legacy Newsletter Platform and Kit (formerly ConvertKit) compared?
Each side's monthly cost is multiplied by the months in the horizon, and the one-time switching cost is added to Kit (formerly ConvertKit). At the default volume (Paid & Free Subscribers: 15,000), the model gives about $425 per month for Substack / Legacy Newsletter Platform and $115 per month for Kit (formerly ConvertKit).
How do Substack / Legacy Newsletter Platform CSV headers map to Kit (formerly ConvertKit)?
The mapper renames Substack / Legacy Newsletter Platform columns (email, name, subscription_type, created_at, stripe_connected) to Kit (formerly ConvertKit) columns (email_address, first_name, tags, created_at, member_status) in your browser. Custom fields must exist in Kit (formerly ConvertKit) before you import.
When should a company stay on Substack / Legacy Newsletter Platform?
Stay if the one-time switching, integration or contract-exit cost is larger than the savings over the horizon you care about. The calculator shows that case as a negative result.