Compare / Claude Opus 5.5 vs Mercury 3
Claude Opus 5.5 vs Mercury 3
Which is cheaper, which is more capable, and which does better at each kind of work, from 46 results on 3 sources that measured both models.
Of the 46 results both models have, the better value on each. Results whose reported ranges overlap are too close to call.
Results as of 20 October 2026 (catalogue release 2026-10-20-96eb40c3ec63).
Claude Opus 5.5 or Mercury 3? The short answer
Pick Claude Opus 5.5 if quality matters most: it scores higher (Spring Prompt overall 85 against 39). Pick Mercury 3 if cost matters more: it costs 22 times less per deck on DeckBench.
- Spring Prompt overall: Claude Opus 5.5 85, Mercury 3 39 (out of 100; how the score works).
- Mercury 3 is cheaper to run: $0.012 against $0.26 per deck on DeckBench (22 times less).
- Mercury 3 is newer: released 19 Oct 2026, against 22 Sep 2026 for Claude Opus 5.5.
- On our own benchmarks, on the results both models have: Claude Opus 5.5 does better for decks from an analysis, user surveys and marketing planning.
Head to head
Every fact side by side
| Claude Opus 5.5 | Mercury 3 | |
|---|---|---|
| Price per million tokens | $4.00 in · $20.00 out | $0.20 in · $0.70 out |
| Blended (3 in : 1 out) | $8.00 | $0.33 |
| Cheapest host, blended | $8.00 (Amazon Bedrock) | – |
| Cost per deck (DeckBench) | $0.26 | $0.012 |
| Cached input, per million | $0.20 cached input | $0.020 cached input |
| Intelligence Index | 57.6 | – |
| Spring Prompt overall | 85 | 39 |
| Output speed, tokens a second | 96 | – |
| Context window | 1,000,000 tokens | 1,000,000 tokens |
| Released | 22 Sep 2026 | 19 Oct 2026 (newer) |
| Weights | Closed | Closed |
| Developer based in | the US | the US |
Prices are the developer's list price where we have read it, otherwise the typical host on OpenRouter; see every model's price. Intelligence and speed from Artificial Analysis.
Which is better for what
Each model's rank among the models on sale today, for each kind of work, from our own benchmarks and licensed sources. Further right is better; the better rank is in green.
Their slides, side by side
The same brief for both: Manchester store investment review for Hearthside Coffee, an invented company. First slide of each deck from DeckBench.
From our research
- AI Checkpoint: Argon matches Opus, until it sells 16 Oct 2026
- Gemini 4 Argon review: Opus-level product data at a quarter of the cost, until you ask it to sell 14 Oct 2026
- Claude Opus 5.5 vs Muse Wonder Full: Eight Crafts, and Opus Still Wins Most 13 Oct 2026
- Muse Wonder review: good analysis, work that still needs checking 13 Oct 2026
Every shared result
Each model's best result on every measure both have, grouped by benchmark, with the setting that produced it. Under each measure, every model that benchmark has measured is a grey tick, best to the right, so you can see where the two sit in the field. The headline measures of each benchmark come first; the rest are under "Show all". Green marks the better value; where a source reports ranges that overlap, neither is marked.
| Measure | Claude Opus 5.5 | Mercury 3 |
|---|---|---|
| DeckBench measured by Spring Prompt · 3 results | ||
| Cost per deckUS dollars, lower is better 21 · 4 of 24 measured | $0.26 | $0.0116 |
| Deck ratingrating, higher is betterThe rating weighs each win by how strong the other deck was; the win rate counts wins against whichever decks a model happened to meet, so the two can disagree. 4 · 18 of 24 measured | 1,436 | 812 |
| Accurate decks% of tasks, higher is better 4 · 20 of 24 measured | 83.3% | 0.0% |
| ROASBench measured by Spring Prompt · 3 results | ||
| Overall scorescore out of 100, higher is better 5 · 18 of 24 measured | 51.7 | 26.1 |
| Audience scorescore out of 100, higher is better 4 · 21 of 24 measured | 67.7 | 43.2 |
| Business scorescore out of 100, higher is better 5 · 18 of 24 measured | 52.3 | 17.6 |
| SurveyBench measured by Spring Prompt · 3 results | ||
| Analysis ratingrating, higher is betterThe rating weighs each win by how strong the other analysis was; the win rate counts wins against whichever analyses a model happened to meet, so the two can disagree. 1 · 9 of 13 measured | 1,499 | 752 |
| Cost per taskUS dollars, lower is better 12 · 3 of 12 measured | $0.46 | $0.0216 |
| Analysis scorepoints of 100, higher is better 3 · 12 of 13 measured | 95.3 | 42.2 |
Show all 46 results (37 more)
| Measure | Claude Opus 5.5 | Mercury 3 |
|---|---|---|
| DeckBench measured by Spring Prompt · 14 results | ||
| Caveat dropped% of tasks, lower is better 12 · 12 of 24 measured | 16.7% | 16.7% |
| Clean layout% of tasks, higher is better 3 · 6 of 24 measured | 83.3% | 66.7% |
| Design quality% of the maximum, higher is better 7 · 16 of 24 measured | 72.0% | 58.5% |
| Draft figure quoted% of tasks, lower is better 1 · 12 of 24 measured | 0.0% | 33.3% |
| Findings missing% of tasks, lower is better 1 · 17 of 24 measured | 0.0% | 16.7% |
| Head-to-head win rate% of comparisons, higher is betterThe rating weighs each win by how strong the other deck was; the win rate counts wins against whichever decks a model happened to meet, so the two can disagree. 3 · 16 of 24 measured | 87.8% | 44.0% |
| Layout defects% of tasks, lower is better 3 · 6 of 24 measured | 16.7% | 33.3% |
| Misleading metric used% of tasks, lower is better 1 · 22 of 24 measured | 0.0% | 16.7% |
| Presentable decks% of tasks, higher is better 5 · 12 of 24 measured | 33.3% | 0.0% |
| Recommendation late or wrong% of tasks, lower is better 1 · 22 of 24 measured | 0.0% | 83.3% |
| Slides needing work% of tasks, lower is better 16 · 7 of 24 measured | 66.7% | 33.3% |
| Time per deckseconds, lower is better 13 · 9 of 24 measured | 98.5 | 83.3 |
| Unsupported claims% of tasks, lower is better 1 · 11 of 24 measured | 0.0% | 16.7% |
| Unsupported numbers% of tasks, lower is better 1 · 20 of 24 measured | 0.0% | 16.7% |
| ROASBench measured by Spring Prompt · 6 results | ||
| Consistency scorescore out of 100, higher is better 7 · 19 of 24 measured | 33.8 | 15.1 |
| Contribution profitsimulated US dollars, higher is better 2 · 18 of 24 measured | $911,566 | $104,868 |
| Cost of a runUS dollars, lower is better 22 · 6 of 24 measured | $1.06 | $0.0533 |
| Months over budgetmonths of 12, lower is better 1 · 1 of 24 measured | 0 | 0 |
| Planning scorescore out of 100, higher is better 16 · 23 of 24 measured | 54.7 | 53.8 |
| Return on ad spendprofit per $1 spent, higher is better 2 · 18 of 24 measured | $0.69 | $0.10 |
| SurveyBench measured by Spring Prompt · 17 results | ||
| Head-to-head win rate% of comparisons, higher is betterThe rating weighs each win by how strong the other analysis was; the win rate counts wins against whichever analyses a model happened to meet, so the two can disagree. 1 · 6 of 13 measured | 83.7% | 48.6% |
| Leading or double-barrelled questions% of tasks, lower is better 1 · 8 of 13 measured | 0.0% | 55.6% |
| Mistaken next steps% of tasks, lower is better 1 · 5 of 13 measured | 0.0% | 22.2% |
| Numbers right% of answers, higher is better 1 · 13 of 13 measured | 100.0% | 63.3% |
| Objectives unanswerable% of tasks, lower is better 1 · 1 of 13 measured | 0.0% | 0.0% |
| Precision ignored% of tasks, lower is better 1 · 1 of 13 measured | 0.0% | 0.0% |
| Research scorepoints of 100, higher is better 2 · 11 of 13 measured | 96.1 | 56.8 |
| Sound research% of tasks, higher is better 2 · 6 of 13 measured | 55.6% | 0.0% |
| Stakeholder's view presumed% of tasks, lower is better 1 · 7 of 13 measured | 0.0% | 22.2% |
| Survey plan scorepoints of 100, higher is better 1 · 6 of 13 measured | 97.8 | 90.8 |
| Survey structure% of tasks, lower is better 3 · 7 of 13 measured | 11.1% | 22.2% |
| Time per taskseconds, lower is better 9 · 10 of 12 measured | 180 | 194 |
| Traps handled% of traps, higher is better 2 · 11 of 13 measured | 95.7% | 60.7% |
| Traps missed% of tasks, lower is better 3 · 7 of 13 measured | 33.3% | 88.9% |
| Unsupported findings% of tasks, lower is better 3 · 4 of 13 measured | 22.2% | 44.4% |
| Wrong numbers% of tasks, lower is better 1 · 9 of 13 measured | 0.0% | 44.4% |
| Wrong recommendation% of tasks, lower is better 1 · 12 of 13 measured | 0.0% | 77.8% |
Compare them with other models
Quick answers
Is Claude Opus 5.5 better than Mercury 3?
Pick Claude Opus 5.5 if quality matters most: it scores higher (Spring Prompt overall 85 against 39). Pick Mercury 3 if cost matters more: it costs 22 times less per deck on DeckBench.
Which is cheaper, Claude Opus 5.5 or Mercury 3?
Mercury 3 is cheaper to run: $0.012 against $0.26 per deck on DeckBench (22 times less).
Which is better for decks from an analysis, Claude Opus 5.5 or Mercury 3?
Claude Opus 5.5 ranks 4 of 24 models on sale for turning a finished analysis into a deck you could present as it is, against 18 for Mercury 3.
Which is better for user surveys, Claude Opus 5.5 or Mercury 3?
Claude Opus 5.5 ranks 1 of 13 models on sale for planning a user survey and reading its results without being misled, against 9 for Mercury 3.
Which is better for marketing planning, Claude Opus 5.5 or Mercury 3?
Claude Opus 5.5 ranks 5 of 24 models on sale for planning a year of ad spend without overspending, against 18 for Mercury 3.
Which is better for speed under pressure, Claude Opus 5.5 or Mercury 3?
Mercury 3 ranks 10 of 28 models on sale for good decisions against a real clock (fast chess), against 28 for Claude Opus 5.5.
Run Claude Opus 5.5 and Mercury 3 on your own prompt
Benchmarks aren't your data. Try both side by side in the playground, with the cost of every answer.