AI API Pricing 2026: GPT-5.6, Claude 5 & Gemini 3 Cost Per Million Tokens

By Gia Gray · Updated September 2026 · 8 min read

The frontier moved again. The models people priced a year ago — GPT-4o, Claude 3.5 Sonnet, Gemini 1.5 — are now legacy, retired, or shut down, and the current generation (OpenAI's GPT-5.6 line, Anthropic's Claude 5 line, and Google's Gemini 3 line) has reshuffled the cost picture. This page is the single, current per-million-token reference I keep coming back to. Every number below was checked against the provider's official pricing page in September 2026; standard (non-batch) rates are shown, and for Gemini's tiered models the figure is the rate for prompts up to 200K tokens.

Current AI API pricing — all major models (per 1M tokens)

Sources: OpenAI, Anthropic, and Google pricing pages, September 2026. Always confirm before making production decisions — these rates change often. (Gemini 3.8 Flash shows promotional pricing in effect through Dec 31, 2026.)

The three flagship tiers, and what they cost

Premium reasoning. GPT-5.6 Sol ($5/$30), Claude Opus 5 ($5/$25), and Gemini 3.1 Pro ($2/$12) sit at the top. Output is where these get expensive — GPT-5.6 Sol's $30/M output is six times its input rate, so an output-heavy workload on a premium model is the fastest way to a surprise bill. Reach for these only when the task genuinely needs frontier reasoning, coding, or analysis.

Workhorse. GPT-5.6 Terra ($2/$12) and Claude Sonnet 5 ($2/$10) are the models most production apps should default to — and note Sonnet dropped to $2/$10 this generation, undercutting its predecessor. Both handle the large majority of real coding, writing, and analysis work at a fraction of premium output cost, with full 1M-token context windows.

Budget / high-volume. GPT-5.6 Luna ($0.20/$1.20), Claude Haiku 4.5 ($1/$5), Gemini 3.8 Flash ($0.75/$3.75), and the Flash-Lite tiers are built for classification, routing, extraction, and anything you run at scale. Running a flagship on these tasks wastes 10–50× on cost for no quality gain.

The cheapest models right now

For pure cost-per-token, Google's Flash-Lite tier leads: Gemini 2.5 Flash-Lite at $0.10 input / $0.40 output is the lowest sticker price among current models. OpenAI's GPT-5.6 Luna ($0.20/$1.20) is the cheapest current-generation frontier option, and the legacy GPT-4o mini ($0.15/$0.60) is still callable. But "cheapest per token" rarely equals "cheapest per result" — a smarter model that solves the task in one pass can beat a cheaper one that needs three attempts. Benchmark on your actual task before committing.

Watch the new cost driver: thinking tokens

The current generation leans heavily on reasoning ("thinking") tokens — internal tokens a model generates before its visible answer. On most current models these are billed at the output rate and can dominate the cost of a single request on hard problems. That shifts the metric that matters from cost per token to cost per correct answer: a pricier reasoning model that gets it right the first time can be cheaper end-to-end than a cheap model you have to re-run. Budget for thinking tokens explicitly on reasoning-heavy workloads.

Prompt caching still pays for itself

All three providers now price cached input at roughly 10% of the base input rate (a 90% discount on the cached portion). If your app re-sends a large, stable system prompt, document, or conversation history on every request, caching is the single biggest lever you have — often a 50–70% cut to total input cost with zero quality change. Batch APIs add another ~50% off for work that doesn't need a real-time response.

What changed recently

If you're updating an old cost model, the headline shifts: OpenAI's GPT-5.4/5.5 gave way to the GPT-5.6 line (Sol / Terra / Luna); Anthropic launched Claude Opus 5 and Sonnet 5, with Sonnet dropping to $2/$10 (down from $3/$15); and Google's Flash line iterated to Gemini 3.8 Flash while Gemini 3.1 Pro remains the Pro flagship. Further back, the Claude 3.x family was retired, and Google discontinued Gemini 1.5 and shut down Gemini 2.0 on June 1, 2026. Net effect: frontier capability keeps getting cheaper, but reasoning/thinking tokens make worst-case request cost harder to predict.