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 the names Kit (formerly ConvertKit) expects. It runs in your browser. Only headers change and values are kept.
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.