Provider pricing pages show per-token rates. What they don't show is your actual monthly bill based on your call volume, prompt sizes, and whether you're using context caching.
So I built LLMCostCalc, a free, browser-based calculator that does that math for you across 8 models: Claude Haiku/Sonnet/Opus, GPT-5 mini/GPT-5/GPT-5 Pro, and Gemini 2.5 Flash/Pro.
Here's what 1,000 calls/day with medium prompts looks like:
| Model | Monthly Cost |
|---|---|
| Gemini 2.5 Flash | $11.70 |
| GPT-5 mini | $23.40 |
| Claude Haiku 4.5 | $144.00 |
| Claude Sonnet 4.6 | $540.00 |
| Claude Opus 4.5 | $2,700.00 |
That's a 230x spread between the cheapest and most expensive option at the same workload.
The tool also models context caching savings for Anthropic and Google models, breaks out input vs output costs separately (output tokens are typically 3-5x pricier), and gives you a plain-English recommendation for the best cost-to-quality tradeoff at your volume.
Everything runs in your browser. No signup, no data sent anywhere.
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