Simon Willison Upgrades Claude Token Counter with Exciting Model Comparisons
product#llm📝 Blog|Analyzed: Apr 20, 2026 00:57•
Published: Apr 20, 2026 00:50
•1 min read
•Simon WillisonAnalysis
Simon Willison has brilliantly upgraded his Claude Token Counter tool to allow developers to easily compare token counts across Anthropic's latest models. This is a fantastic utility for those practicing Prompt Engineering, as it highlights the new tokenizer introduced in Claude Opus 4.7. It provides immediate, practical value by helping the community optimize their inputs and understand token inflation costs firsthand.
Key Takeaways
- •Claude Opus 4.7 introduces Anthropic's first updated tokenizer, offering improved text processing.
- •The new Opus 4.7 tokenizer increases token count by roughly 1.0-1.35x, making usage about 40% more expensive despite identical per-token pricing.
- •The upgraded tool supports counting tokens for all four current notable models and includes support for higher-resolution images up to ~3.75 megapixels.
Reference / Citation
View Original"I upgraded my Claude Token Counter tool to add the ability to run the same count against different models in order to compare them."