OpenAI API Cost Calculator

Estimate GPT-4o, GPT-4o-mini, and GPT-4-turbo API costs — and compare against Claude and Gemini in one place

OpenAI API Pricing (May 2025)

Model Input (per 1M tokens) Output (per 1M tokens) Cached Input Context
GPT-4o $5.00 $15.00 $2.50 (auto) 128k
GPT-4o-mini $0.15 $0.60 $0.075 (auto) 128k
GPT-4-turbo $10.00 $30.00 N/A 128k
o1 (reasoning) $15.00 $60.00 $7.50 (auto) 200k
o3-mini $1.10 $4.40 $0.55 (auto) 200k

Quick Cost Estimates: Common API Call Sizes

These calculations assume 500 input tokens (a medium-length prompt) + various output sizes.

GPT-4o — cost per API call

500 input + 100 output tokens $0.0040
500 input + 500 output tokens $0.0100
2,000 input + 500 output tokens $0.0175
10,000 input + 1,000 output tokens $0.0650

GPT-4o-mini — cost per API call

500 input + 100 output tokens $0.000135
500 input + 500 output tokens $0.000375
2,000 input + 500 output tokens $0.000600
10,000 input + 1,000 output tokens $0.002100

Monthly Bill Estimator: 10,000 calls/day

Model Avg tokens/call Daily cost Monthly cost
GPT-4o 700 total $55.00 $1,650
GPT-4o-mini 700 total $1.95 $58.50
Claude Sonnet 3.5 700 total $45.00 $1,350
Claude Haiku 3.5 700 total $12.00 $360

Use the Interactive Calculator

Paste any real prompt text and instantly see the cost across GPT-4o, Claude, and Gemini — no signup, no token counting required.

Open LLM Pricing Calculator →

Frequently Asked Questions

How do I calculate my OpenAI API cost?

OpenAI charges separately for input (prompt) and output (completion) tokens. For GPT-4o: $5/M input + $15/M output. Count your tokens (≈4 characters each), multiply by the rate. Our free calculator handles this automatically — paste any prompt for an instant cost breakdown.

How much does a single GPT-4o API call cost?

A typical call with a 500-token prompt and 300-token response costs ~$0.0070 (under 1 cent). At 10,000 calls/day that's $70/day or ~$2,100/month. GPT-4o-mini cuts this by 20–30× to about $0.000225/call.

Is there a free OpenAI API cost estimator?

Yes — this page and our interactive tool at prompt-pricing.vercel.app are both free with no signup. Paste your prompt text and see the exact cost across all major LLM providers simultaneously.

What is OpenAI's prompt caching discount?

OpenAI caches repeated prompt prefixes automatically at 50% off the input rate. GPT-4o cached tokens: $2.50/M. This activates without any special API parameters when the same prefix appears in recent requests. Claude's explicit caching offers a deeper 90% discount but requires adding cache control markers to your API calls.

Also see: GPT-4o vs Claude Full Comparison · Claude vs GPT Pricing Deep Dive · Gemini API Pricing · LLM Cost Comparison 2026 · Claude Haiku Pricing