Claude Sonnet 5.5 is the best AI for cover letters because it writes like a person: varied sentences, a clear point, and a tone that fits the company rather than a template. The best results come from giving it three things — the job description, your resume, and one or two lines on why you actually want the role — and asking for something under 250 words.
The safest cover letters default, the cheaper option worth trying first, and the specialist pick — before you read the detail below.
Claude Sonnet 5.5 is the strongest answer here for cover letters — pick it when quality of output matters more than the $2.00/1M/1M input you pay for it.
Claude Haiku 5.5 handles the same job for about 95% less per token. Start here and only move up if the output is not good enough.
GPT-6.1 Sol is the fastest of these for cover letters — worth it when latency is what the reader notices, not the last few points of reasoning depth.
Claude Sonnet 5.5 is the best cover-letter model for tone and polish.
Claude Haiku 5.5 is the efficient choice when you need many quick drafts.
GPT-6.1 Sol helps when the role calls for more technical or analytical positioning.
Use Claude Sonnet 5.5 for final letters and the applications you care most about.
Use Claude Haiku 5.5 to draft company-specific versions quickly.
Use GPT-6.1 Sol when you need sharper reasoning about role fit, projects or technical claims.
Switch the scoring lens to see whether the cover letters answer changes when cost, speed, or long-document depth leads the decision.
Anthropic / Balanced / Oct 10, 2026
Near-Opus 5.5 quality on scoped work at half the price.
Ranks models by the broadest mix of coding, writing, research, and long-context usefulness.
The work is long, ambiguous and multi-step — Anthropic positions Opus 5.5 for exactly that — or you need the lowest possible price, where Haiku 5.5 costs a twentieth as much.
Where the cover letters recommendation shifts once you weigh price or latency differently.
Near-Opus 5.5 quality on scoped work at half the price.
Anthropic's budget model, now with adjustable reasoning, at $0.10/$0.50.
Near-Astra capability at Sol pricing — OpenAI's value pick.
List prices and published scores — the numbers this page's pick is built from.
| Model | Input | Output | Est. month | Context | Speed | Coding | Writing | Research |
|---|---|---|---|---|---|---|---|---|
| Claude Sonnet 5.5Anthropic | $2.00/1M | $10.00/1M | $40 | 1M tokens | Fast | 98 | 98 | 95 |
| Claude Haiku 5.5Anthropic | $0.10/1M | $0.50/1M | $2.00 | 1M tokens | Very fast | 86 | 84 | 82 |
| GPT-6.1 SolOpenAI | $2.00/1M | $10.00/1M | $40 | 1.1M tokens | Balanced | 98 | 94 | 97 |
Scores out of 100 — how we evaluate models. “Est. month” is 10M in / 2M out at list price: a ceiling, no discounts.
Why each one is on the shortlist for cover letters, what it is genuinely good at, and where we would steer you away from it.
The default answer for cover letters — 98/100 on the coding axis, and the model we would start with unless the price below rules it out.
Anthropic's September 28, 2026 Sonnet — built for well-scoped everyday work like features, bug fixes, documents, slides and spreadsheets, priced at $2/$10 and close to Opus 5.5 on most of Anthropic's launch rows.
The work is long, ambiguous and multi-step — Anthropic positions Opus 5.5 for exactly that — or you need the lowest possible price, where Haiku 5.5 costs a twentieth as much.
The model most people should default to in the Claude lineup. Sonnet 5.5 lands within a few points of Opus 5.5 on most of Anthropic's launch rows, beats it on Terminal-Bench 4.0, and costs half as much. Step up to Opus 5.5 only when the task is open-ended and long.
Full pricing, benchmark table and release notes on the Claude Sonnet 5.5 page.
Where most budgets should land for cover letters — about 95% less per token than Claude Sonnet 5.5, and still 86/100 on the coding axis.
Anthropic's October 7, 2026 low-cost model and the first Haiku with adjustable reasoning effort — thinking can be switched off for simple requests or raised to max, at $0.10/$0.50 per 1M under 100K input tokens.
Your prompts routinely exceed 100K tokens, where the price quintuples, or the task needs sustained reasoning that Sonnet 5.5 handles far better.
The cheapest way to put an Anthropic model in a high-volume pipeline. Keep requests under 100K tokens to stay on the low rate, and set effort per task — at low effort it is a fast classifier, at max it handles real tool-use work.
Full pricing, benchmark table and release notes on the Claude Haiku 5.5 page.
Here for latency: it answers fastest of anything listed for cover letters, at 98/100 on coding.
Near-Astra capability at Sol pricing — OpenAI's value pick. Full GPT-6.1 Sol review →
UseRightAI recommendations are based on practical decision factors people actually feel in day-to-day use.
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For cover letters, Claude Sonnet 5.5 (Anthropic) is our pick. Near-Opus 5.5 quality on scoped work at half the price. It costs $2/1M input and $10/1M output tokens, with a 1M-token context window — enough headroom for all but the largest cover letters jobs. Claude Haiku 5.5 is the closest alternative if it doesn't fit your setup.
Because the work it is built for overlaps closely with cover letters: day-to-day feature and bug-fix work in an IDE or coding agent, where speed matters more than ceiling and drafting documents, slide decks and spreadsheets that need to be presentable on the first pass. The model most people should default to in the Claude lineup. Sonnet 5.5 lands within a few points of Opus 5.5 on most of Anthropic's launch rows, beats it on Terminal-Bench 4.0, and costs half as much. Step up to Opus 5.5 only when the task is open-ended and long.
On a moderate month — 10M input and 2M output tokens — Claude Sonnet 5.5 runs about $40.00 at list price, with no batch or caching discounts applied, so treat that as a ceiling. Claude Haiku 5.5 is the cheaper route at roughly $2.00 for the same volume, if cover letters is high-volume enough for price to lead the decision.
Anthropic itself says Opus 5.5 is better on loosely defined tasks that need longer reasoning. Trails Opus 5.5 on Humanity's Last Exam (64.5% vs 67.7%). Avoid it if the work is long, ambiguous and multi-step — Anthropic positions Opus 5.5 for exactly that — or you need the lowest possible price, where Haiku 5.5 costs a twentieth as much. None of that rules it out for cover letters 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.
Claude Haiku 5.5 at $0.1/1M input is the budget option here. Anthropic's budget model, now with adjustable reasoning, at $0.10/$0.50. Expect a quality step down on the hardest cases — the usual pattern is to route routine cover letters volume to Claude Haiku 5.5 and keep Claude Sonnet 5.5 for the work where a wrong answer is expensive.
Claude Haiku 5.5, rated very fast against Claude Sonnet 5.5's fast. Speed matters most for interactive and high-volume work; if your cover letters runs in the background, the slower and more capable model is usually the better trade.