Model comparison · accepted catalogue facts 2026-10-21
Claude Opus 4.8 vs Claude Opus 5.5
Claude Opus 5.5 has an equal-or-higher measured score and an equal-or-lower estimated price. No known model-capability loss from Claude Opus 4.8; endpoint and task checks still apply. The reported score intervals do not overlap; this is not a task-specific success guarantee.
Editorial comparison: Anthropic generational trade-off: Claude Opus 5.5 vs Claude Opus 4.8 for capability versus token price Inclusion does not recommend either model.
Balanced effective USD / 1M tokens · lower is better
$8.00/M
In-Depth Analysis
Claude Opus 4.8 vs Claude Opus 5.5: Measured Technical Breakdown
Comprehensive comparison across measured human-preference evaluation, effective production token costs, architectural limits, and migration trade-offs.
Measured Capability (LMArena)
Claude Opus 5.5 leads by 54.4 Elo
Claude Opus 4.8: 1461.1 ±3.87 · Claude Opus 5.5: 1515.5 ±7.52 Statistically significant preference separation
Cost Comparison Across Canonical Production Workloads
Rates represent effective cost per 1M tokens under standard token blends. Cached prompt reads are factored according to workload context reuse.
Workload & Ratio
Claude Opus 4.8
Claude Opus 5.5
Cost Difference
Advantage
Balanced3 tokens in per 1 out
$10.00/1M tokens
$8.00/1M tokens
$2.00(20% diff)
Claude Opus 5.5 costs less
SummariseHuge input, tiny output
$4.72/1M tokens
$3.72/1M tokens
$1.00(21% diff)
Claude Opus 5.5 costs less
ChatLong cached system prompt
$11.65/1M tokens
$9.26/1M tokens
$2.39(21% diff)
Claude Opus 5.5 costs less
Code genOutput dominates
$16.64/1M tokens
$13.30/1M tokens
$3.34(20% diff)
Claude Opus 5.5 costs less
AgenticContext replayed each turn
$5.32/1M tokens
$4.14/1M tokens
$1.18(22% diff)
Claude Opus 5.5 costs less
Architectural & Operational Specifications
Specification
Claude Opus 4.8
Claude Opus 5.5
Operational Note
Context window
1,000,000 tokens
1,000,000 tokens
—
Max output generation
128,000 tokens
128,000 tokens
—
Base input price
$5.00 / 1M tokens
$4.00 / 1M tokens
Claude Opus 5.5 input rate is cheaper
Base output price
$25.00 / 1M tokens
$20.00 / 1M tokens
Claude Opus 5.5 output rate is cheaper
Cached input price
$0.500 / 1M tokens
$0.200 / 1M tokens
Claude Opus 5.5 offers lower cached prompt cost
Reasoning & thinking tokens
Supported; standard rates
Supported; standard rates
—
Input modalities
text, image, file
text, image, file
—
Tool calling / function use
Supported
Supported
—
Open weights & licence
Proprietary (proprietary)
Proprietary (API-only)
—
Provider & reseller market
Anthropic · 11 provider offers
Anthropic · 11 provider offers
—
When to Choose Claude Opus 4.8
Direct integration with Anthropic tooling and API features.
When to Choose Claude Opus 5.5
Higher measured general capability (1515.5 Elo on human evaluation).
Direct integration with Anthropic tooling and API features.
These settings are included in the share link. The fixed-request scenario and private evaluation data below are excluded.
A ↔ B
Claude Opus 5.5 has an equal-or-higher measured score and an equal-or-lower estimated price. No known model-capability loss from Claude Opus 4.8; endpoint and task checks still apply. The reported score intervals do not overlap; this is not a task-specific success guarantee.
Estimated blend: 75% input, 25% output; 0% cached input. Base context tier. Prompt length selects the billing tier. An unlisted cache-read rate uses that tier’s full input rate in this blend; missing required input or output rates prevent an estimate. The fixed-request estimate below validates actual context and output limits and requires a published cache-read rate when cache hits are assumed.
What changes between these models
Quality first, then estimated price. LMArena scores are human-preference measurements, not a benchmark of your application. A missing score is unrated.
Claude Opus 4.8 · Meets the stated model requirements
Claude Opus 5.5 · Meets the stated model requirements
Material differences and unknown evidence. Deltas compare each model with model A. Unknown facts remain visible.
Provider counts and precision flags describe catalogue offers. They do not establish the precision, availability, region, tool behaviour or limits of your chosen endpoint. Open each model’s provider table before switching.
Rates below are USD per 1M tokens. A threshold selects that whole input/output rate pair.
Input-token threshold
Input
Output
Cached input
Base, up to and including first threshold
$4
$20
$0.2
Migration preflight · compare each candidate with model A
Keeping Claude Opus 4.8 is a valid decision. No pairwise comparison certifies a drop-in replacement.
Claude Opus 4.8 → Claude Opus 5.5
No known model-capability loss
Provider endpoint, serving precision, availability and task success need your own verification. Catalogue model capabilities do not certify an endpoint.
Private to this tab unless you save locally or explicitly export private details. These are estimates, not observed invoices. Cross-model token counts and task success are assumptions.
0.1 extra attempts means 10 extra full attempts per 100 requests. Cache writes, tool charges, taxes and unlisted charges are excluded.
Claude Opus 4.8Estimated total: $22.5 1,000 full attempts · base rates
Claude Opus 5.5Estimated total: $18 1,000 full attempts · base rates
Prompt and output sensitivity · sampled scenarios
Every point recalculates the entire request shape. Tier-boundary samples include one token below, at and above each threshold. Ordering between samples is not guaranteed. Lowest known cost excludes unknown estimates and is not a replacement recommendation.
Vary input; hold output, requests, cache and retries fixed.
Input tokens
Claude Opus 4.8
Claude Opus 5.5
Coverage
2,000
$22.5
$18Lowest known
All computed
4,096
$32.98
$26.384Lowest known
All computed
32,768
$176.34
$141.072Lowest known
All computed
131,072
$667.86
$534.288Lowest known
All computed
Vary output; hold input, requests, cache and retries fixed.
Output tokens
Claude Opus 4.8
Claude Opus 5.5
128
$13.2
$10.56
2,048
$61.2
$48.96
8,192
$214.8
$171.84
Bring your observed evaluation results
JSON is parsed locally. Prompts, filenames, individual responses and extra fields are not retained. Import only aggregate measurements for selected models. Task/version labels do not establish that two evaluations used the same dataset.
Use the exact catalogue ID. Replace the example values with observed measurements. Omit costUsd or latencyMs when they are unknown. No public score is inferred from these observations.
Keep the decision and its evidence
A portable record retains selected facts, complete tier ladders, public requirements and the publication manifest. It also embeds the full permitted public catalogue to verify the input artifact checksum. Files are larger for this reason (up to 2 MB); local storage is limited to 12 records. Team review is local to this browser; there is no hosted collaboration.
Saving is opt-in and includes private review fields. Shared comparison links never include them. Version 1 Check references remain separate and are not overwritten or guessed into this format.
Saved local decisions · 0
No version 2 decision records are stored in this browser.
Questions this page answers
Is Claude Opus 4.8 a better-and-cheaper replacement for Claude Opus 5.5?
Claude Opus 5.5 has an equal-or-higher measured score and an equal-or-lower estimated price. No known model-capability loss from Claude Opus 4.8; endpoint and task checks still apply. The reported score intervals do not overlap; this is not a task-specific success guarantee.
Which model is higher rated: Claude Opus 4.8 or Claude Opus 5.5?
Claude Opus 5.5 scores higher on LMArena general (1515.5 ±7.5) compared to Claude Opus 4.8 (1461.1 ±3.9), a margin of 54.4 Elo points. The measured confidence intervals do not overlap, demonstrating a statistically significant preference lead on human evaluations.
Which model is more cost-effective: Claude Opus 4.8 or Claude Opus 5.5?
On a standard balanced workload (3 prompt tokens per 1 generated token), Claude Opus 5.5 costs $8.00 per 1M tokens versus $10.00 for Claude Opus 4.8. Claude Opus 4.8 is approximately 1.3× the price of Claude Opus 5.5. Base input rates are $5.00 for Claude Opus 4.8 and $4.00 for Claude Opus 5.5; base output rates are $25.00 for Claude Opus 4.8 and $20.00 for Claude Opus 5.5.
How do their context windows and generation limits compare?
Both Claude Opus 4.8 and Claude Opus 5.5 provide an identical 1,000,000-token context window. Maximum output generation limits are 128,000 tokens for Claude Opus 4.8 and 128,000 tokens for Claude Opus 5.5.
What capabilities are lost when switching between Claude Opus 4.8 and Claude Opus 5.5?
Neither model exhibits a confirmed loss in declared context or modalities when switching between them. However, differences in tokenizer efficiency, prompt alignment, and latency across providers should be benchmarked on task-specific test suites.
Can Claude Opus 4.8 or Claude Opus 5.5 be self-hosted or deployed privately?
Both Claude Opus 4.8 and Claude Opus 5.5 are proprietary cloud models offered via managed API endpoints. Claude Opus 4.8 is served by Anthropic and 11 catalogue offers, while Claude Opus 5.5 is served by Anthropic and 11 catalogue offers.
What is included in this comparison?
Accepted model capabilities, context and output limits, complete price-tier ladders, independent LMArena measurements and missing evidence. Provider endpoint precision and application success still need verification.
Can I compare a different workload or keep a decision record?
Yes. Change the public workload, prompt length and requirements in the comparison workspace. Fixed-request scenarios, aggregate evaluations and review notes stay local unless explicitly exported.
