Claude Opus 5 vs GPT-5.6 Sol: the price ranking flips

This is the clearest example on the site of why list-price comparisons mislead. GPT-5.6 Sol carries a lower published list price than Claude Opus 5 — but the two are discounted differently, and once both are priced at current gateway rates the cheaper model changes. Work through the table before you decide — comparing these two on vendor list prices alone leads to the opposite conclusion to the one these rates support.

In short: Claude Opus 5 is priced at $2.5/$12.5 per 1M input/output tokens on the gateway; GPT-5.6 Sol at $2.5/$15. On a workload where one third of tokens are output, Claude Opus 5 is 13% cheaper, and the gap reaches $83.33 a month at 100M tokens. Note the reversal above: GPT-5.6 Sol's list price is lower, but its discount against list is smaller, so at gateway rates Claude Opus 5 is the cheaper of the two. Rates checked 2026-09-16.

Claude Opus 5 vs GPT-5.6 Sol: the numbers side by side

	Claude Opus 5	GPT-5.6 Sol
Gateway rate — input	$2.5	$2.5
Gateway rate — output	$12.5	$15
Official list — input	$5	$4
Official list — output	$25	$20
Blended at 1/3 output	$5.83	$6.67
Output : input price ratio	5.0×	6.0×

USD per 1M tokens. Gateway rates checked 2026-09-16; official list prices as published by each vendor. Gateway rates move with upstream promotions — re-check before committing a budget.

The ranking flips once you price it at gateway rates. On published official list prices, GPT-5.6 Sol is the cheaper of the two. At current gateway rates the answer reverses: Claude Opus 5 comes out about 13% cheaper on a 1/3-output workload. Price comparisons built only from vendor list prices will tell you the opposite — which is the most common way this particular choice gets made wrong.

What each costs per month

Monthly tokens	Claude Opus 5	GPT-5.6 Sol	Cheaper
10M	$58.33	$66.67	Claude Opus 5 — 13% less
100M	$583	$667	Claude Opus 5 — 13% less
1000M	$5,833	$6,667	Claude Opus 5 — 13% less

Assumes 1/3 of tokens are output and 2/3 input — roughly a chat or coding-agent mix. At a 100M tokens/month workload the gap is $83.33 a month, or $1,000 a year. Change the split in the calculator — output-heavy workloads widen the gap.

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How much tokens each budget buys

Budget	Claude Opus 5	GPT-5.6 Sol	Extra tokens
$100	17M	15M	Claude Opus 5 — 2M more
$1,000	171M	150M	Claude Opus 5 — 21M more

Tokens purchasable at the blended rate above. Output tokens cost more than input, so reading these figures as "all input" would overstate them.

Which one to pick

If you are choosing between two frontier models, price is usually not the deciding factor — quality on your workload is. Use the price data here for the opposite purpose: to confirm that the model you actually want is affordable at your volume, and to find the volume at which it stops being affordable.

Compare on the ratio, not the rate. The output:input ratio row tells you how much more you pay for generated tokens. A model with a lower ratio is more forgiving of verbose output, long reasoning traces and code generation — the parts of an agent workload that blow up.
Check the 1B row. Frontier models at a billion tokens a month is a real budget line. If it is, the discount structure matters more than the sticker price, and that is exactly what the flip above is about.
Model both, ship one. Run the same eval set through both and compare quality per dollar rather than price per token. The calculator will give you the dollar side.

Switching between them

Both models are called through the same endpoint, so this is a model-ID change, not a migration. Setup references: OpenAI & Anthropic SDK · Claude Code · Cursor · reducing API cost.

Related comparisons: Claude vs GPT (mid-tier) · Opus 5 vs Sonnet 5 · Lowest-cost LLM APIs

FAQ

Is Claude Opus 5 or GPT-5.6 Sol cheaper?

At current gateway rates Claude Opus 5 is cheaper for a mixed workload — $5.83 versus $6.67 per 1M tokens blended at one third output. The answer depends on your input/output split: output tokens are priced several times higher than input on both models (5x and 6x respectively), so an output-heavy workload widens the gap.

How much does Claude Opus 5 cost per month?

At $5.83 per 1M blended tokens: about $58.33 for 10M tokens a month, $583 for 100M, and $5,833 for 1B. That is pure token spend — there is no subscription on either model.

How much does GPT-5.6 Sol cost per month?

At $6.67 per 1M blended tokens: about $66.67 for 10M tokens a month, $667 for 100M, and $6,667 for 1B.

Can I switch between them without rewriting my code?

Both are reached through the same gateway endpoint, so switching is a model-ID change in the request rather than a new integration. See the SDK guide for the one-line change, or the Claude Code setup if you are switching inside a coding agent.

Which one should I use for long-context work?

That is a capability question rather than a pricing one, and it is not something a price index should answer for you. Check each vendor's own documentation for context limits, then price the context volume you actually expect — long-context workloads are input-dominated, so the input rate and the blended column are the rows that matter most.

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