Executive Summary
Success Rate
Only Infinite Library completed the full 30K words
Generation Time
vs 4+ hours with other tools
Cost Savings
vs monthly subscriptions
We Tested Jasper AI vs Copy.ai vs Infinite Library: Here's What Actually Happened
After seeing countless claims about AI book writing tools, we decided to put them to the test. We attempted to create identical 30,000-word business books using Jasper AI, Copy.ai, and Infinite Library. The results were eye-opening.
Testing Methodology
How We Conducted the Test
Book Project:
- • Topic: "Complete Guide to Starting an Online Business in 2025"
- • Target length: 30,000 words
- • Genre: Non-fiction business guide
- • Required 12 chapters with consistent formatting
Testing Criteria:
- • Identical prompt used for all platforms
- • Time tracked for complete generation
- • Content quality assessed by 3 reviewers
- • Total cost calculated including subscriptions
Detailed Results by Platform
Jasper AI Results
Words Generated
Separate Sessions
Total Time
Monthly Cost
What Happened:
- • Jasper AI hit word limits after ~500 words per generation
- • Required manual prompting and chapter organization
- • Lost context and coherence across sessions
- • Generated repetitive content in later chapters
- • Final output was only 14% of target length
Verdict: Jasper AI is excellent for marketing copy but not designed for book-length content.
Copy.ai Results
Words Generated
Separate Sessions
Time Spent
Monthly Cost
What Happened:
- • Copy.ai limited to very short content pieces (~150 words each)
- • No book-specific templates or organization features
- • Output felt like disconnected marketing snippets
- • Gave up after 6 hours with only 6% of target complete
- • Would need 100+ separate generations for a full book
Verdict: Copy.ai is designed for marketing copy, not long-form content creation.
Infinite Library Results
Words Generated
Single Session
Total Time
One-time Cost
What Happened:
- • Generated complete 30,000-word book in single session
- • Maintained consistent tone and style throughout
- • Automatic chapter organization and professional formatting
- • Coherent narrative flow from introduction to conclusion
- • Required minimal editing for publication readiness
Verdict: Infinite Library is purpose-built for book creation and delivers exactly what it promises.
Key Findings
✅ What Worked
- • Infinite Library: Complete book generation in one session
- • Consistent quality and formatting throughout
- • One-time cost vs. recurring subscriptions
- • Publication-ready output with minimal editing
❌ What Failed
- • Jasper AI: Word limits prevented book completion
- • Copy.ai: Not designed for long-form content
- • Both required extensive manual work
- • Neither could maintain coherence across chapters
True Cost Analysis
| Platform | Success Rate | Time to Complete | Cost for 30K Words | Cost per Year |
|---|---|---|---|---|
| Infinite Library | 100% | 15 minutes | $69.99 | $69.99 |
| Jasper AI | 14% | 4+ hours | $39/month+ | $468/year |
| Copy.ai | 6% | 6+ hours | $36/month+ | $432/year |
Conclusion
The results speak for themselves: while Jasper AI and Copy.ai are excellent for their intended purposes (marketing copy and short content), they simply cannot deliver on book-length projects.
Infinite Library completed our 30,000-word test book in 15 minutes with consistent quality throughout. The other tools couldn't even reach 15% completion after hours of work.
For anyone serious about AI book writing, the choice is clear: specialized tools like Infinite Library deliver results that general AI writing tools simply cannot match.