ModelSpec is an analysis of alternatives for AI models: it decides which models fit a job from your requirements, sourced benchmarks and real cost, and shows its work.
Claude Opus 4.7 vs Claude Opus 5.5 for Coding (balanced), as of 2026-09-23
Find an active coding model with room for a repository that balances coding strength against task cost.
Worked example as of 2026-09-23, from the public data image.
What the evidence says
The evidence separates them: Claude Opus 5.5 leads for Coding (balanced), with a 22% chance of being the best model in the full lineup for this job, as of 2026-09-23.
Claude Opus 4.7 has a 22% chance of matching or beating Claude Opus 5.5 on this job's objective.
probability bands: a model joins the leader when P(its score >= the leader's) >= 0.25 under the score posteriors; a weighted capability with an 80% interval wider than 2.8 is not enough evidence
Decision status: partial. P(best) and score intervals retain the full ranked lineup for this job, including models beyond this pair and models with thin evidence. Models with unknown objective values remain unranked and are outside this probability. P(best) is not a head-to-head probability. Separation from this challenger need not mean a unique best model across that lineup.
Scores and score intervals use the objective's dimensionless normalised units. Cost per task is in USD for the selected offering and the applied spec's task size. When task size is omitted, the engine uses its documented default. Unavailable means the engine returned no value.
| Model | Score | Score interval | P(best), ranked job lineup | Cost per task, USD | Selected offering: provider / region / tier | Capability estimates and intervals |
|---|---|---|---|---|---|---|
| Claude Opus 4.7 | 0.711629 | [0.52433, 0.898928] | 2% | 0.3 | anthropic / global / standard |
|
| Claude Opus 5.5 | 0.894595 | [0.657556, 1.131633] | 22% | 0.24 | anthropic / global / standard |
|
Coding strength first, cost as a real second term.
Requirements
model.class = text-generator: Coding work needs a model that generates text and code.model.lifecycle = active: An active model is still supported by its lab or provider.model.context_window >= 200000: A large repository needs room for code, tests, and instructions.
Preferences
software_engineering: Prefer stronger evidence on real software-engineering tasks.-offering.cost_per_task: Among strong coders, prefer the cheaper task.
Applied template spec
spec_version- 1
where- model.class = text-generator
- model.lifecycle = active
- model.context_window >= 200000
optimizeweightssoftware_engineering- 0.7
-offering.cost_per_task- 0.3
Evidence for Claude Opus 4.7
| Benchmark | Version | Measurement | Unit | Published interval | Evidence date | Measurement conditions | Provenance |
|---|---|---|---|---|---|---|---|
| arena_sc_coding | text_style_control / coding, latest split, revision 1880dbebff5b | 1551.79 | Arena score (Elo scale) | Unavailable | 2026-09-13 |
| Source |
| arena_sc_industry_software_it_services | text_style_control / industry_software_and_it_services, latest split, revision 1880dbebff5b | 1540.9 | Arena score (Elo scale) | Unavailable | 2026-09-13 |
| Source |
| arena_webdev | webdev / overall, latest split, revision 1880dbebff5b | 1555.64 | Arena score (Elo scale) | Unavailable | 2026-09-23 |
| Source |
| frontiercode_v1_1 | FrontierCode 1.1, main score (Mean@5) | 38.5 | percent | Unavailable | 2026-09-30 |
| Source |
| swe_bench_verified | SWE-bench Verified (Epoch AI run) | 83.47 | percent | Unavailable | 2026-04-20 |
| Source |
Missing facts for Claude Opus 4.7
model.hardware_fit_indeterminate: unknownmodel.languages: unknownmodel.parameters_total: unknownorigin.base_lineage: not_disclosedorigin.weights_hosting: not_disclosedoffering.api_model_id: unknownoffering.data.zero_retention: requires_contractoffering.private_deployment: unknownoffering.router_slug: unknownoffering.speed.throughput: unknownoffering.speed.time_to_first_token: unknown
Evidence for Claude Opus 5.5
| Benchmark | Version | Measurement | Unit | Published interval | Evidence date | Measurement conditions | Provenance |
|---|---|---|---|---|---|---|---|
| arena_webdev | webdev / overall, latest split, revision 1880dbebff5b | 1818.41 | Arena score (Elo scale) | Unavailable | 2026-09-23 |
| Source |
| cursorbench_4 | CursorBench 4.0 | 57.8 | percent | Unavailable | 2026-09-30 |
| Source |
| swe_bench_multilingual | SWE-bench Multilingual | 93.9 | percent | Unavailable | 2026-09-22 |
| Source |
| swe_bench_multimodal | SWE-bench Multimodal | 61.4 | percent | Unavailable | 2026-09-22 |
| Source |
| swe_bench_pro | SWE-bench Pro | 89.9 | percent | Unavailable | 2026-09-22 |
| Source |
| terminal_bench_v4_0 | Terminal-Bench 4.0 | 66.4 | percent | Unavailable | 2026-09-22 |
| Source |
Missing facts for Claude Opus 5.5
model.hardware_fit_indeterminate: unknownmodel.languages: unknownmodel.parameters_total: unknownorigin.base_lineage: not_disclosedorigin.weights_hosting: not_disclosedoffering.api_model_id: unknownoffering.data.zero_retention: requires_contractoffering.private_deployment: unknownoffering.router_slug: unknownoffering.speed.throughput: unknownoffering.speed.time_to_first_token: unknown
What this template teaches
A 70/30 blend keeps capability in charge while letting a large price gap decide close calls.
Decision dec_522f407374f23603bb2a189d on public snapshot snap_05a963d2477ac2fb.
Read the full dated job answer.
The live board uses current data. This link applies the template to its full lineup.
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