Email writing is the highest-volume professional writing task most people do. The best AI for email handles tone calibration, brevity, and context shifts across inbox types without requiring constant editing.
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Rankings refresh dailyScored on 6 criteriaNo paid rankings
Best pick right now
AnthropicPremium
Claude Sonnet 5
Best value Claude — agentic Sonnet speed with near-Opus capability.
Anthropic's new Mythos-class flagship and the most capable coding model anyone can use — 80.3% SWE-Bench Pro, an 11-point jump over Opus 4.8. 1M context, 128K output, native parallel subagents. Released June 9, 2026.
Verdict
New global #1 — 80.3% SWE-Bench Pro, the most capable model generally available.
Quality score
98%
Pricing
$10.00/1M in
$50.00/1M out
Speed
Deliberate
2/5 speed
Context
1M tokens
Launched June 9, 2026 as the public, Mythos-class release. Available on the Claude API, Microsoft Foundry, and Google Vertex AI. Free for all users until June 22, 2026. Same underlying model as Claude Mythos 5, with safeguards that block specific high-risk cyber responses.
Coding leaderSWE-Bench Pro #1Mythos-classParallel subagentsAgenticLong contextPremiumNew
Best for
The hardest coding tasks, autonomous multi-step agents, and frontier-grade reasoning
Anthropic's September 1, 2026 frontier release and the new capability ceiling for coding, agents, and scientific work. Base pricing is unchanged at $10/$50, but cache reads dropped 75% to $0.25/1M — roughly 25% cheaper on typical workloads and up to 45% cheaper on agentic ones. 1M context, 128K output, adaptive thinking always on.
Verdict
New frontier leader — better than Fable 5 on every published benchmark, and cheaper to run.
Quality score
98%
Pricing
$10.00/1M in
$50.00/1M out
Speed
Deliberate
2/5 speed
Context
1M tokens
Released September 1, 2026 alongside Claude Mythos 5.1, the first update to the Mythos-class line since Fable 5 on June 9. API ID claude-fable-5-1; generally available on the Claude API, Amazon Bedrock, Google Cloud, and Microsoft Foundry. Published launch numbers (Fable 5.1 / Fable 5 / Opus 5 / GPT-5.6 Sol): Terminal-Bench-Science 0.1 52.6 / 24.7 / 29.0 / 22.4; Terminal-Bench 4.0 55.8 / 42.0 / 52.3 / 37.3; CursorBench 3.2.0 73.4 / 70.5 / 70.0 / 67.2; AutomationBench 31.4 / 17.1 / 26.9 / 19.6; OSWorld 2.0 strict 41.7 / 36.1 / 39.6; Humanity's Last Exam (no tools) 60.9 / 57.8 / 56.6; GDPval-AA v2 1853 / 1723 / 1824 / 1711. GDPval-AA v2 is rescaled from the v1 numbers quoted on the Fable 5 page and is not directly comparable to them.
OpenAI's September 3, 2026 frontier release — the first GPT-6 model and OpenAI's answer to Claude Fable 5.1 two days earlier. State of the art on computer use (OSWorld 2.0 72.6% in ~47% less time than GPT-5.6 Sol), agentic coding (Terminal-Bench 4.0 57.9%), and frontier math (FrontierMath Tier 4 97.6%). $10/$50 per 1M tokens, 1.05M context, 128K output, knowledge cutoff April 30, 2026.
Verdict
OpenAI's frontier answer to Fable 5.1 — computer-use and agentic-coding leader at $10/$50.
Quality score
99%
Pricing
$10.00/1M in
$50.00/1M out
Speed
Deliberate
2/5 speed
Context
1.1M tokens
Released September 3, 2026. API ID gpt-6-astra; rolling out over the coming days to ChatGPT Plus, Pro, Business and Enterprise (usage inside existing allowances; GPT-6 Astra Pro for Pro/Business/Enterprise; Enterprise off by default), the OpenAI API, Microsoft Azure and Amazon Bedrock. Standard API pricing $10/$50 per 1M tokens; Fast mode is up to 2x speed at 2x price; cache reads and writes have separate rates. Model docs list 1,050,000 context, 128,000 max output, knowledge cutoff April 30, 2026, reasoning efforts up to 'max'. Published launch numbers (Astra / GPT-5.6 Sol / Fable 5.1 / Opus 5): OSWorld 2.0 72.6 / 65.7 / — / 70.2; Terminal-Bench 4.0 57.9 / 37.3 / 55.8 / 52.3; Terminal-Bench Science 0.1 64.6 / 22.4 / 52.6 / 30.0; FrontierMath Tier 4 v2 97.6 / 83.0 / 87.8 / 73.2; GPQA Diamond 96.0 / 94.6 / 93.7 / 93.7; Humanity's Last Exam w/ tools 57.2 / — / 65.0 / 63.6; AutomationBench 41.4 / 18.1 / 31.4 / 26.9; DeepSWE v1.1 74.1 / 72.7 / 67.4 / 73.7; ARC-AGI-2 95.0 / 92.5 / 90.0 / 90.4; ARC-AGI-3 99.9 (OpenAI responses-API harness; ARC Prize's stateless runs score far lower) / 7.8 / — / 30.2; ExploitBench 100.0 / 78.5 / — / 70; SRE-Bench 88.0 / 55.9; Artificial Analysis Intelligence Index v4.1.1 61.2 / 60.9 / 65.7 / 63.1. Meets the Critical threshold for cybersecurity under OpenAI's Preparedness Framework; advanced cyber workflows gated behind OpenAI Daybreak. All figures from OpenAI's launch post and model docs, verified September 4, 2026.
Computer use leaderFrontierAgenticReasoningLong contextPremiumNew
Best for
Computer and browser use, long-horizon agentic coding, and frontier math and science work
Ranked first here for email writing: 98/100 on writing, with the widest margin of anything in this line-up.
Anthropic's most agentic Sonnet yet — a fast 1M-context workhorse that narrows the gap to Opus-class quality at $3/$15, and the new default model on claude.ai.
Input
$2.00/1M
Output
$10.00/1M
Context
1M tokens
Speed
Fast
What people actually use it for
Production agent loops that plan, call tools, verify output, and finish multi-step tasks
High-volume coding assistance at one-fifth of Opus 5's price
Computer-use automation — 78.5% on OSWorld-Verified
Where it wins
72.7% on SWE-bench Verified (vs Sonnet 4.6's 62.3% on the same eval) with launch promo pricing of $2/$10 through August 31, 2026
78.5% OSWorld-Verified computer use and 46.8% on Humanity's Last Exam with tools
1M-token context in the fast Sonnet latency class — Opus-adjacent quality without Opus latency
Where it falls down
Clearly behind Opus 5 and Fable 5 on the hardest reasoning and long-horizon agent tasks
Updated tokenizer produces ~1.0–1.35x more tokens for the same text, so effective cost runs above sticker price
Skip it if
You need the absolute top coding ceiling — Opus 5 leads SWE-bench Verified by over 20 points.
Our verdict
The best price-to-capability pick in the Claude lineup. Sonnet 5 replaces Sonnet 4.6 as the production default: markedly better agentic coding and computer use at the same standard price, with a $2/$10 promo through August 2026.
The fastest model in this shortlist for email writing. Pick it when turnaround is what your readers or users notice.
The default model powering Cursor and Windsurf. 79.6% SWE-bench, 1M context window, and best-in-tier writing quality — all at $3/1M input.
Input
$3.00/1M
Output
$15.00/1M
Context
1M tokens
Speed
Balanced
What people actually use it for
Daily coding in Cursor — debugging, refactoring, and feature implementation
Drafting polished client reports, strategy memos, and long-form editorial content
Answering research questions with up to 1M tokens of document context
Where it wins
Strong coding quality with 1M context at $3/1M input
Default model in Cursor and Windsurf, the two most popular AI coding editors
Best writing quality in its price tier — tone, long-form clarity, editorial polish
Where it falls down
Claude Opus 4.7 has a higher current premium coding ceiling
GPT-5.5 or GPT-5.4 are better picks when OpenAI computer-use workflows are the priority
Skip it if
You specifically need desktop-control capabilities (GPT-5.5/GPT-5.4) or the absolute highest coding ceiling (Opus 4.7).
Our verdict
The best all-around model for most developers and writers. Strong SWE-bench, excellent writing, 1M context — all at $3/1M input. Hard to beat as a daily driver.
Rounds out the shortlist for email writing at 98/100 on writing.
Input
$10.00/1M
Output
$50.00/1M
Context
1M tokens
Speed
Deliberate
New frontier leader — better than Fable 5 on every published benchmark, and cheaper to run. Full Claude Fable 5.1 review →
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FAQ
What is the best AI for email writing?
For email writing, Claude Sonnet 5 (Anthropic) is our pick. Best value Claude — agentic Sonnet speed with near-Opus capability. It costs $2/1M input and $10/1M output tokens, with a 1M-token context window — enough headroom for all but the largest email writing jobs. Claude Sonnet 4.6 is the closest alternative if it doesn't fit your setup.
Why Claude Sonnet 5 for email writing?
Because the work it is built for overlaps closely with email writing: production agent loops that plan, call tools, verify output, and finish multi-step tasks and high-volume coding assistance at one-fifth of Opus 5's price. The best price-to-capability pick in the Claude lineup. Sonnet 5 replaces Sonnet 4.6 as the production default: markedly better agentic coding and computer use at the same standard price, with a $2/$10 promo through August 2026.
What does it cost to use Claude Sonnet 5 for email writing?
On a moderate month — 10M input and 2M output tokens — Claude Sonnet 5 runs about $40.00 at list price, with no batch or caching discounts applied, so treat that as a ceiling. It is also the cheapest option among the models compared here, so for email writing there is no cost argument for dropping to something weaker.
When is Claude Sonnet 5 the wrong choice for email writing?
Clearly behind Opus 5 and Fable 5 on the hardest reasoning and long-horizon agent tasks. Updated tokenizer produces ~1.0–1.35x more tokens for the same text, so effective cost runs above sticker price. Avoid it if you need the absolute top coding ceiling — Opus 5 leads SWE-bench Verified by over 20 points. None of that rules it out for email writing on its own — but if one of those limits maps onto how you actually work, take the alternative on this page seriously rather than defaulting to the top pick.