When should a company stay on Substack (10% Cut) / Legacy Newsletter instead of switching to Kit (formerly ConvertKit)?

Staying on Substack (10% Cut) / Legacy Newsletter is recommended if your one-time onboarding, custom API re-engineering, or contract termination costs exceed the 12-to-24 month subscription difference.

⚡ Evaluation Driver: Losing 10% of paid newsletter revenue to Substack platform fees Illustrative Model (Editable) • Oct 2026

Substack (10% Cut) / Legacy Newsletter vs Kit (formerly ConvertKit): TCO & CSV Schema

12〜36ヶ月の総所有コスト（初期移行コスト含む）を無料で試算。年払い割引とマルチカレンシー決済の最適化を組み合わせ、ブラウザ内で安全にCSVヘッダーをマッピングできます。

1. 総所有コスト (TCO) ＆コスト最適化シミュレーター

利用規模、請求サイクル、初期移行コストを設定して試算

Creator Economy & Paid Newsletters

Paid & Free Subscribers:

請求プラン

比較期間

初期移行コスト ($)

現在: Substack (10% Cut) / Legacy Newsletter

--/mo

Total TCO: --

Base $50 + $/unit:

代替案: Kit (formerly ConvertKit)

--/mo

Total TCO (incl. switch): --

Base $25 + $/unit:

⚙️ Credit / Tier Complexity Multiplier (for Credit Bundles & Tiered Plans):

Pricing Methodology Note: Because SaaS vendors often price via stepped tiers, email/contact brackets, or variable credit bundles, use the editable $/unit inputs and Credit Multiplier above to match your exact contract quote. Verify published tier rules at Kit (formerly ConvertKit) Official Pricing & Docs ↗.

Estimated Net TCO Difference

Break-even payback: --

Formula: --

Evaluating...

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Kit (formerly ConvertKit) 公式サイトで最新料金を確認する →

2. ローカルCSVヘッダーマッパー

Tabular CSV Headers Only

Substack (10% Cut) / Legacy Newsletter から出力したCSV列名をブラウザ内で Kit (formerly ConvertKit) 形式に変換します（※CSVのヘッダー行のみを変換します）。

⚠️ Import Readiness & Consent Warning: Renaming CSV column headers does NOT make a file automatically import-ready. Custom attributes must be created in the target platform first, and unsubscribed/opt-out lists must be verified separately to preserve GDPR consent status. Does not convert JSON workflow blueprints.

Source (Substack (10% Cut) / Legacy Newsletter)		Target (Kit (formerly ConvertKit))	Field Type / Note
email	→	email_address	Documented System Field
name	→	first_name	Documented System Field
subscription_type	→	tags	Custom Attribute (Create field before import)
created_at	→	created_at	Documented System Field
stripe_connected	→	member_status	Status Field (Verify GDPR/Opt-Out separately)

Input Sample CSV (Max 5,000 rows): Escape formulas (=,+,-,@)

Mapped CSV Output Preview:

✅ Kit (formerly ConvertKit) への移行が適している場合

Your primary cost driver is Losing 10% of paid newsletter revenue to Substack platform fees and your monthly volume exceeds the break-even threshold shown above.
Your team can complete CSV data import and staff onboarding within your budgeted switching cost without disrupting active workflows.
You have verified that Kit (formerly ConvertKit)'s current plan tier supports your required integrations and regional compliance rules.

✋ Substack (10% Cut) / Legacy Newsletter を継続すべき場合

Your one-time migration, custom API re-engineering, or staff retraining costs exceed the 12-to-24 month subscription difference.
You are locked into a multi-year agreement on Substack (10% Cut) / Legacy Newsletter with early termination penalties.
Your workflow depends on custom legacy plugins that are not yet supported by Kit (formerly ConvertKit).

3. Technical Sensitivity Benchmark: Substack (10% Cut) / Legacy Newsletter vs Kit (formerly ConvertKit)

Schema Columns Mapped: 5 fields

The table below models 12-month Total Cost of Ownership across three volume tiers for Paid & Free Subscribers (including a baseline $150 one-time switching cost on the alternative plan). For credit-heavy or non-linear tier plans, use the interactive Credit Multiplier above.

Volume Scenario (Paid & Free Subscribers)	Current (Substack (10% Cut) / Legacy Newsletter)	Alternative (Kit (formerly ConvertKit))	12-Mo Net TCO Outcome
Low Scale (0.5x) (7,500 Paid & Free Subscribers)	$238/mo ($2,856/yr)	$70/mo ($990/yr incl. $150 switch)	+$1,866 net reduction
Default Baseline (1.0x) (15,000 Paid & Free Subscribers)	$425/mo ($5,100/yr)	$115/mo ($1,530/yr incl. $150 switch)	+$3,570 net reduction
High / Enterprise Scale (2.5x) (37,500 Paid & Free Subscribers)	$988/mo ($11,856/yr)	$250/mo ($3,150/yr incl. $150 switch)	+$8,706 net reduction

よくある質問 (FAQ) とTCO算出ロジック

How is Total Cost of Ownership (TCO) calculated between Substack (10% Cut) / Legacy Newsletter and Kit (formerly ConvertKit)?

SwitchBridge models Substack (10% Cut) / Legacy Newsletter (illustrative base $50/mo + $0.025 per Paid & Free Subscribers) against Kit (formerly ConvertKit) (base $25/mo + $0.006 per Paid & Free Subscribers), adding one-time switching costs and billing cycle adjustments. At a sample scenario of 15000 Paid & Free Subscribers, estimated monthly costs are ~$425/mo vs ~$115/mo before switching expenses.

How do I map Substack (10% Cut) / Legacy Newsletter CSV headers to Kit (formerly ConvertKit) import format?

Exported Substack (10% Cut) / Legacy Newsletter CSV columns (email, name, subscription_type, created_at, stripe_connected) map to Kit (formerly ConvertKit) target columns (email_address, first_name, tags, created_at, member_status) using the local browser CSV header mapper above. Custom attributes must be defined in Kit (formerly ConvertKit) prior to import.

Is SwitchBridge free compared to paid SaaS deal clubs?

Yes. Unlike gated SaaS clubs that charge $199–$499/year for membership, all 61 SwitchBridge TCO calculators and local CSV schema mappers are 100% free ($0 forever) and require no account registration.