Claude Opus 5 vs GPT-5.6 Pricing Calculator: Compare API Costs
Claude Opus 5 and the three GPT-5.6 tiers (Sol, Terra, Luna) price input tokens similarly but diverge sharply on output and long-context handling. Opus 5 charges $5.00/M input and $25.00/M output with a flat rate regardless of prompt length. GPT-5.6 Sol matches Opus 5 on input ($5.00/M) but charges more for output ($30.00/M), while Terra ($2.50/M in, $15.00/M out) and Luna ($1.00/M in, $6.00/M out) undercut both flagships for lighter workloads. The number that actually decides your bill is your input-to-output token ratio: coding agents that read a lot of context but generate relatively little code favor Opus 5 or Terra, while chat-heavy or generation-heavy workloads shift the math toward Luna. There is also a billing trap unique to GPT-5.6: prompts over 272,000 input tokens get billed at a higher rate for the entire request, not just the overage — a cliff Claude Opus 5's flat pricing does not have. Enter your own monthly token volume below, or use the typical coding-agent preset, to see live monthly costs for all four options ranked cheapest to most expensive.
Updated July 25, 2026 · By Jim Liu
At a Glance: 2026 Pricing
| Model | Input $/MTok | Output $/MTok | Context window |
|---|---|---|---|
| Claude Opus 5 · Anthropic | $5.00/M | $25.00/M | 1M tokens |
| GPT-5.6 Sol · OpenAI | $5.00/M | $30.00/M | ~1.05M tokens |
| GPT-5.6 Terra · OpenAI | $2.50/M | $15.00/M | ~1.05M tokens |
| GPT-5.6 Luna · OpenAI | $1.00/M | $6.00/M | ~1.05M tokens |
GamsGo
Access Claude Pro and ChatGPT Plus at 30-40% below standard pricing via group subscription
Monthly Cost Calculator
20M input + 4M output tokens/month — a 5:1 ratio reflecting heavy context reads with modest generated output.
Context, tool output, repo reads, system prompt
Generated code, completions, responses
At 20M input + 4M output tokens/month, GPT-5.6 Luna is $176/mo cheaper than GPT-5.6 Sol.
These totals use flat per-token rates on your monthly volume — they don't model GPT-5.6's per-request 272K-token surcharge (see below), since that depends on your individual request sizes, not just the monthly total.
Which Tier Fits Your Use Case
- • Claude Opus 5 — best-quality agentic coding despite the output-price premium over Terra/Luna. Ranks #1 of 215 models on BenchLM's July 2026 leaderboard (85.88/100, SWE-bench Verified 96.0%), and its flat per-token pricing has no long-context surcharge.
- • GPT-5.6 Terra — for budget-conscious teams needing near-flagship coding performance at roughly half of Opus 5's output cost ($15.00/M vs $25.00/M).
- • GPT-5.6 Luna — for high-volume simple tasks: CI helpers, code review comments, test generation. Lowest per-token cost of the four ($1.00/M input, $6.00/M output).
- • GPT-5.6 Sol — specifically when you need "ultra mode" subagent-swarm parallelism for one very hard task and don't mind the highest output price in the set ($30.00/M).
The 272K-Token Billing Gotcha
GPT-5.6 prompts containing more than 272,000 input tokens get billed at a higher rate for the entire request — not just the tokens over the threshold. That is a real cost cliff for long-context deployments: whole-repository analysis, long document processing, or any workload that occasionally crosses the line. Claude Opus 5 doesn't have this problem — its $5.00/M input and $25.00/M output rates are flat regardless of prompt length, up to its 1M-token context window. If your workload regularly sends prompts near or above 272K tokens, factor this in before the monthly-cost numbers above look final.
Frequently Asked Questions
- It depends on your input/output ratio. Opus 5 and GPT-5.6 Sol both charge $5.00/M input, but Opus 5’s output price ($25/M) is lower than Sol’s ($30/M). GPT-5.6 Terra is cheaper than both for near-flagship coding quality at $2.50/M input and $15/M output. For pure cost-per-token at scale, GPT-5.6 Luna ($1.00/M input, $6.00/M output) is the lowest of any tier compared here — but it trades off model capability.