Simon Willison benchmarks GPT-6 Astra vs GPT-5.6 on SVG: max effort costs 63 cents per call
gaganghotra_ · x · 2026-09-05
Simon Willison got access to OpenAI's GPT-6 Astra and ran his classic pelican SVG task against GPT-5.6's Sol, Terra and Luna, comparing output across reasoning-effort levels with full token and cost accounting.
Pricing (per 1M input/output tokens): Astra $10/$50, Sol $5/$30, Terra $2.50/$15, Luna $1/$6.
Key numbers:
- Max effort: Astra emits 12,638 tokens at 63.21 cents per call, roughly 8x the 7.83 cents Luna charges at the same effort.
- Low effort: Astra 9.55 cents vs Luna 0.76 cents.
- Astra doesn't offer a "none" effort tier; the other three do.
The takeaway: higher reasoning effort dramatically inflates output tokens and cost, with up to an order of magnitude spread across tiers — and Astra is the priciest option at every level.
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