What this tool does
The AI Tool Cost Comparison Calculator helps you estimate and compare the real monthly costs of using different AI tools like ChatGPT, Claude, Gemini, and any other LLM-based service. Instead of relying on stale pricing tables, you enter each tool's current subscription fee and per-token API rates yourself, then describe your personal usage pattern (messages per day, average input tokens per message, average output tokens per message). The calculator computes the total monthly cost for each tool, breaks it down into subscription vs. token usage components, and shows you which option is cheapest for your specific usage. Results include a bar chart comparison, per-tool breakdowns, cost-per-message metrics, and a detailed comparison table so you can make an informed decision.
How it calculates
The calculator uses these core formulas:
1. Monthly messages equals messages per day multiplied by 30. 2. Monthly input token cost equals (monthly messages multiplied by average input tokens per message, divided by 1,000,000) multiplied by the input token rate per million tokens. 3. Monthly output token cost equals (monthly messages multiplied by average output tokens per message, divided by 1,000,000) multiplied by the output token rate per million tokens. 4. Total monthly cost equals the subscription fee plus the monthly input token cost plus the monthly output token cost. 5. Cost per message equals (average input tokens divided by 1,000,000 multiplied by input rate) plus (average output tokens divided by 1,000,000 multiplied by output rate). This represents the token cost only, excluding the subscription. 6. Annual cost equals total monthly cost multiplied by 12. 7. Savings equals the difference between the most expensive tool's monthly cost and the cheapest tool's monthly cost.
Who should use this
1. Developers and engineers choosing between AI APIs (OpenAI, Anthropic, Google) for a project and wanting to understand the cost at their expected usage volume. 2. Individuals deciding between ChatGPT Plus, Claude Pro, and Gemini Advanced subscriptions based on how heavily they use AI tools each day. 3. Startup founders budgeting AI tool costs for their team and wanting to compare options before committing to a vendor. 4. Freelancers and consultants who use AI daily and want to optimize which tools they pay for based on actual usage patterns. 5. Engineering managers evaluating the cost impact of switching their team from one AI provider to another.
Worked examples
Example 1: A developer sends 30 messages per day with 500 input tokens and 1,000 output tokens on average. They compare ChatGPT (GPT-4o) at \$20/mo subscription, \$2.50/1M input tokens, \$10.00/1M output tokens against Claude (Sonnet) at \$20/mo, \$3.00/1M input, \$15.00/1M output.
Monthly messages = 30 x 30 = 900. ChatGPT input cost = (900 x 500 / 1,000,000) x \$2.50 = \$1.13. ChatGPT output cost = (900 x 1,000 / 1,000,000) x \$10.00 = \$9.00. ChatGPT total = \$20.00 + \$1.13 + \$9.00 = \$30.13/month. Claude input cost = (900 x 500 / 1,000,000) x \$3.00 = \$1.35. Claude output cost = (900 x 1,000 / 1,000,000) x \$15.00 = \$13.50. Claude total = \$20.00 + \$1.35 + \$13.50 = \$34.85/month. ChatGPT saves \$4.72/month (\$56.64/year) at this usage level.
Example 2: A heavy user sends 100 messages per day with 800 input tokens and 2,000 output tokens on average. They compare three tools: ChatGPT at \$20/mo, \$2.50/\$10.00 per million tokens; Claude at \$20/mo, \$3.00/\$15.00; and Gemini at \$20/mo, \$1.25/\$5.00.
Monthly messages = 100 x 30 = 3,000. Gemini input cost = (3,000 x 800 / 1,000,000) x \$1.25 = \$3.00. Gemini output cost = (3,000 x 2,000 / 1,000,000) x \$5.00 = \$30.00. Gemini total = \$20.00 + \$3.00 + \$30.00 = \$53.00/month. Claude total = \$20.00 + \$7.20 + \$90.00 = \$117.20/month. Switching to Gemini saves \$64.20/month (\$770.40/year) compared to Claude at this volume.
Limitations
This calculator assumes a uniform usage pattern where every message has the same average input and output token count. In practice, token counts vary dramatically between short questions and long code reviews. It does not account for free tier allowances, usage caps on subscription plans, or rate limits that may throttle your usage. The tool does not model context window costs where longer conversations accumulate more input tokens over time. Pricing for AI services changes frequently, so always verify current rates on each provider's pricing page. The comparison treats all tools as functionally equivalent, which they are not, and quality differences, speed, and feature availability should factor into your decision alongside cost.
FAQs
Q: Where do I find the token pricing for each AI tool? A: Check each provider's API pricing page. OpenAI publishes rates at platform.openai.com/pricing, Anthropic at docs.anthropic.com, and Google at ai.google.dev/pricing. Rates vary by model (GPT-4o vs GPT-4, Sonnet vs Opus, etc.).
Q: How do I estimate my average tokens per message? A: A rough rule of thumb is that 1 token is approximately 4 characters or 0.75 words in English. A typical short prompt is 100-300 tokens. A detailed prompt with context is 500-2000 tokens. API dashboards from OpenAI and Anthropic show your actual token usage.
Q: Should I include the subscription cost if I only use the API? A: If you only use the API and do not pay for a subscription plan, set the subscription cost to 0. The calculator will then show pure API usage costs.
Q: Why are the costs different from what I see on my bill? A: Your actual bill may include system prompts, conversation history (which adds input tokens as context grows), retries, and other overhead not captured by a simple per-message estimate. This tool gives you a baseline comparison.
Q: Can I compare more than three tools? A: Yes. Click "Add Another Tool" to add as many AI tools as you need. You can compare any number of tools side by side.
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