gpt-5.6-terra vs gpt-6-astra
Fourteen priced metrics for the same 2,000-in / 300-out call, with and without provider caching, and what TokenZero's cascade would do with the pair.
At list prices as of 2026-10-26, gpt-5.6-terra costs $3.30 per million blended tokens on a 2,000-in / 300-out call against $15.22 for gpt-6-astra, 78.3% less. With the static prefix cached both drop further: $4.90 versus $21.50 per thousand calls. TokenZero routes only prompts its classifier scores simple and holds a 99.8% parity floor.
· Source: provider list prices verified in pricing table 2026-10-26; costs computed by the same code that signs TokenZero receipts
At a glance
- Cheaper per blended token
- gpt-5.6-terra by 78.3% (computed)
- gpt-5.6-terra blended $/1M
- $3.30 (computed)
- gpt-6-astra blended $/1M
- $15.22 (computed)
- Input $/1M
- $2.00 vs $10.00
- Output $/1M
- $12.00 vs $50.00
- Cached input $/1M
- $0.200 vs $1.000
- Cache discount
- 90% vs 90% (computed)
- Monthly at 100k calls
- $760 vs $3,500 (computed)
- Saved per 1M calls
- $27,400 (computed)
- Providers
- openai vs openai
- Lifecycle
- active, no retirement announced vs active, no retirement announced
- Parity floor for routing
- 99.8% (shadow-eval breaker)
gpt-5.6-terra vs gpt-6-astra: list prices and the same workload on both (USD, table 2026-10-26)
| Metric | gpt-5.6-terra | gpt-6-astra | Delta |
|---|---|---|---|
| Provider · tier | openai · mid | openai · frontier | same provider |
| Input $/1M | $2.00 | $10.00 | 80% gap |
| Output $/1M | $12.00 | $50.00 | 76% gap |
| Cached input $/1M | $0.200 | $1.000 | 90% / 90% off input |
| Cache write $/1M | $2.500 | $12.500 | |
| Minimum cacheable prefix | 1024 tokens | 1024 tokens | |
| Effective blended $/1M (2,000 in / 300 out) | $3.30 | $15.22 | gpt-5.6-terra 78.3% less |
| Per call | $0.00760 | $0.03500 | $0.02740 |
| Per month at 100k calls | $760 | $3,500 | $2,740 |
| …with the 1,500-token prefix cached | $490 | $2,150 | $1,660 |
| Long-context threshold | 272,000 tokens ($4.00 in / $18.00 out above) | 272,000 tokens ($20.00 in / $75.00 out above) | |
| Processing tiers | flex 0.5x · fast 2x | flex 0.5x · fast 2x · ultrafast 6x | |
| Lifecycle | active, no retirement announced | active, no retirement announced | |
| Cheaper sibling (cascade target) | gpt-5.6-luna | gpt-6.1-sol | |
| TokenZero cascade recommendation | gpt-6-astra → gpt-5.6-terra | $27,400 saved per 1M calls if every call moved; $10,960 at a 40% simple-prompt share | 99.8% parity floor, breaker on |
Use either model through TokenZero
OPENAI_BASE_URL=https://tokenzero.sh/v1
# keep your own keys; cache formatting on, routing advisory, signed receipt per callFree up to $500/month of routed spend; paid plans take 15% of verified savings with a 3x-ROI-or-$0 rule.
What is not on this page
Third-party quality scores (coding ELO, extraction accuracy, reasoning benchmarks) and per-model latency are not shown because TokenZero does not measure them; the numbers above are prices and the arithmetic on them. The latency benchmark shows what the gateway does measure.
Questions people ask
Which is cheaper, gpt-5.6-terra or gpt-6-astra?
gpt-5.6-terra. At list prices as of 2026-10-26 it costs $3.30 per million blended tokens versus $15.22 for gpt-6-astra, a 78.3% gap on a 2,000-input / 300-output call. Per month at 100,000 calls that is $760 versus $3,500.
How much does prompt caching change the gpt-5.6-terra vs gpt-6-astra gap?
Cached input costs $0.200 on gpt-5.6-terra and $1.000 on gpt-6-astra per million. With a 1,500-token static prefix cached, 100,000 calls cost $490 and $2,150 respectively; TokenZero's formatter places the breakpoints and sets prompt_cache_key automatically.
Can TokenZero route gpt-6-astra traffic to gpt-5.6-terra safely?
Yes, within openai: with X-TokenZero-Cascade: auto the classifier scores each prompt and only simple ones move; shadow evaluation re-runs a sample on gpt-6-astra and a pair below 99.8% parity is auto-disabled. Moving every call would save $27,400 per million calls; at a 40% simple share it is $10,960.
Is gpt-5.6-terra or gpt-6-astra being retired?
gpt-5.6-terra: active, no retirement announced. gpt-6-astra: active, no retirement announced. TokenZero audits flag retired ids and the gateway warns in X-TokenZero-Warning with the provider's replacement.