How are AI API costs calculated?

API cost equals (input tokens / 1,000,000 x input price) plus (output tokens / 1,000,000 x output price). Most providers bill input and output tokens at different rates, with output usually 4-5x more expensive.

How can I reduce my AI API costs?

Use a smaller model for simple tasks, enable prompt caching for repeated context, trim system prompts, cap output length, and route requests by complexity. A gateway like KissAPI also lowers per-token cost versus official pricing.

AI API Cost Calculator (2026): Claude, GPT-5 & Gemini Pricing Estimator

How this calculator works

AI APIs bill per token, and they charge different rates for the tokens you send (input) and the tokens the model generates (output). The formula is simple:

cost = (input_tokens / 1,000,000 × input_price) + (output_tokens / 1,000,000 × output_price)

This tool multiplies your per-request token counts by your monthly request volume, then applies both KissAPI and official provider rates so you can see the gap. Output tokens dominate most bills because they're priced 4-5x higher than input, so trimming response length is usually the fastest way to cut spend.

2026 pricing reference (per 1M tokens)

Model	Input	Output	Context
Claude Opus 4.6	$3.00	$15.00	200K
Claude Sonnet 4.6	$0.60	$3.00	200K
Claude Haiku 4.5	$0.16	$0.80	200K
GPT-5	$0.50	$2.00	128K
GPT-5.5	$1.50	$6.00	128K

Prices shown are KissAPI rates. All models run through one OpenAI-compatible endpoint, so switching is a one-line base URL change.

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Tips to lower your AI API bill

Match the model to the task. Use Haiku or GPT-5 for classification and simple replies; save Opus for hard reasoning.
Cap output length. Set max_tokens so the model can't ramble. Output is the expensive half.
Cache repeated context. If you resend the same system prompt or documents, prompt caching can cut input cost dramatically.
Trim your prompts. Long system prompts get billed on every request. Tighten them once and save forever.

Frequently asked questions

How many tokens is 1,000 words?

Roughly 1,300-1,400 tokens for English text. A common rule of thumb is 1 token ≈ 0.75 words, or about 4 characters.

Why is output more expensive than input?

Output tokens are generated one at a time and need more compute per token, so providers price them 4-5x higher than input tokens.

Are these prices accurate?

They reflect KissAPI's 2026 rates. Provider pricing can change, so always confirm current rates on the pricing page before budgeting.

Does KissAPI charge subscriptions?

No. It's pay-as-you-go. You top up a balance and pay per token, with no monthly commitment.