The Confusion Problem
Every AI subscription advertises generous usage, but they all measure it differently. OpenAI uses “unlimited*” with guardrails. Anthropic counts messages per 5-hour window. Google uses AI credits. Cursor uses dollar budgets. Windsurf uses prompt credits.
Understanding what you actually get requires translating each vendor’s system into comparable terms.
The Five Limit Models
1. OpenAI: Dynamic Guardrails
Plans: ChatGPT Plus ($20/mo), Pro ($200/mo)
OpenAI does not publish fixed message caps. Instead, Plus offers “unlimited*” interactions with dynamic guardrails that throttle usage during peak demand. Pro gets higher priority and fewer restrictions.
What this means in practice: You rarely hit hard walls, but during busy periods, responses may slow down or you may be temporarily downgraded to a lighter model. Credit top-ups cover Codex and Sora usage beyond included allocations.
2. Anthropic: Session-Based Windows
Plans: Claude Pro ($20/mo), Max 5x ($100/mo), Max 20x ($200/mo)
Anthropic uses a 5-hour rolling window. Claude Pro guarantees at least 45 short messages per window, resetting every 5 hours. Message length affects the count — longer prompts consume more of the allocation.
What this means in practice: You get predictable bursts of usage with clear reset times. If you hit the cap, you wait for the window to reset (max 5 hours). Extra usage can be toggled on at API rates.
3. Google: AI Credit System
Plans: AI Plus ($7.99/mo), AI Pro ($19.99/mo), AI Ultra ($249.99/mo)
Google uses a monthly credit pool — 200, 1,000, or 25,000 credits depending on tier. Different operations consume different amounts: a simple query might use 1 credit, while a reasoning-heavy prompt or media generation task uses more.
What this means in practice: You have a clear monthly budget but must track consumption. Daily Pro prompt caps (30, 100, or highest) prevent burning through monthly credits too quickly.
4. Cursor: Dollar-Denominated Budgets
Plans: Pro ($20/mo), Pro+ ($60/mo), Ultra ($200/mo)
Cursor includes a dollar amount of API usage: $20, $70, or $400 per month respectively. You see exactly how much each interaction costs because it is billed against your included budget at API rates.
What this means in practice: Full cost transparency. You can see real-time spend in your dashboard. After the included budget, usage continues at on-demand API rates with no hard cutoff.
5. Windsurf: Prompt Credits
Plans: Pro ($15/mo)
Windsurf allocates 500 prompt credits per month. Each interaction consumes one or more credits depending on complexity. Additional credits can be purchased at $10 per 250 credits.
What this means in practice: Simple to understand, but the credit-to-interaction ratio varies by task complexity. Heavy agent usage depletes credits faster than simple chat.
Side-by-Side Comparison
| Vendor | System | $20 Tier Allocation | Overage Handling |
|---|---|---|---|
| OpenAI | Dynamic guardrails | Unlimited* (throttled) | Credit top-ups |
| Anthropic | Session windows | 45+ msgs / 5 hrs | API rate toggle |
| AI credits | 1,000 credits/mo | Daily cap limits burn rate | |
| Cursor | Dollar budget | $20 API budget | On-demand at API rates |
| Windsurf | Prompt credits | 500 credits/mo ($15) | $10 / 250 credits |
Which System Is Best for You?
- Hate tracking usage? OpenAI’s unlimited* feel is the least friction.
- Want predictability? Anthropic’s session windows have clear reset times.
- Want transparency? Cursor’s dollar budgets show exactly what you spend.
- On a budget? Windsurf at $15/month or Google AI Plus at $7.99/month offer the lowest entry points.