Claude vs DeepSeek for writing

Every limit is published. Paid plans also have a monthly fair-use limit on AI cost: Pro $7.50, Max $20, Ultra $42, Studio $85. Using every message on your plan at typical sizes stays under it; very large messages and heavy research use it faster. Every limit, explained.

Writing: Claude Sonnet 5 passed 4 of 5 and DeepSeek V4.1 Flash 4 of 5. DeepSeek V4.1 Flash answered 1.5× sooner at the median, 4.5 s against 3.1 s. DeepSeek V4.1 Flash cost 12.0× less, $0.0171 against $0.0014 for the 5 replies. Claude Sonnet 5's replies ran 84% longer, in tokens of reply, thinking not counted.

1. 1. Announce a second bakery shop on LinkedIn

   Everyday. Claude: 4 of 5 models passed, Claude Haiku 4.5 the cheapest at $0.0013 · DeepSeek: 2 of 2 models passed, DeepSeek V4.1 Flash the cheapest at $0.0002. The prompt in full.

   DeepSeek V4.1 Flash passed this one and Claude Sonnet 5 didn't. DeepSeek V4.1 Flash answered sooner (2.9 s to 4.6 s), and DeepSeek V4.1 Flash's reply cost less ($0.0002 to $0.0037); Claude Sonnet 5 wrote 267 tokens of reply, DeepSeek V4.1 Flash 184.

   • Claude Sonnet 5

     Failed: Graded 3.5 of 5 on average (lowest 3).

     We have some exciting news to share: Crumb & Co. is opening our second shop, this time in Leeds!
     
     From our very first bakery, we've believed in doing simple things well — proper sourdough, honest pastries, and coffee worth stopping for. Now we get to bring that same spirit to a new neighbourhood and, hopefully, a whole new group of familiar faces.
     
     Our Leeds shop opens its doors on 14 November, and we'd love for you to be there. To celebrate, every coffee on opening day is on us — no catch, just our way of saying thank you for supporting us along the way.
     
     This has been months of planning, a lot of taste-testing, and more excitement than we know what to do with. We can't wait to welcome you in, share some fresh bakes, and start building new memories together.
     
     See you there — first coffee's on the house.

     538 tokens in, 267 out · 4.6 s · $0.0037 · 1 message on Pro · answered by anthropic/claude-sonnet-5 via Claude Platform on AWS · September 27, 2026

   • DeepSeek V4.1 Flash

     Passed: Graded 5.0 of 5 on average (lowest 5).

     Some news we've been sitting on for a while: Crumb & Co. is opening a second shop, in Leeds, on 14 November.
     
     We started six years ago with one oven, one counter and a lot of very early mornings. The idea was simple — good bread, made slowly, sold to people who'd walk a bit out of their way for it. That we get to do it in a second place still feels a little unreal.
     
     The new shop will have the same loaves, the same pastries, the same slightly chaotic Saturday mornings. There's more seating, and a window that actually gets sun.
     
     To say thank you, coffee is free all day on opening day. No catch, no app, no code — just come in and we'll make you one.
     
     We'd love to see you there. Thank you for getting us this far.
     
     — The Crumb & Co. team

     428 tokens in, 203 out (19 of them reasoning) · 2.9 s · $0.0002 · 1 message on Pro · answered by deepseek/deepseek-v4.1-flash via GMICloud · September 27, 2026

2. 2. Rewrite corporate jargon in plain words

   Everyday. Claude: 5 of 5 models passed, Claude Haiku 4.5 the cheapest at $0.0008 · DeepSeek: 1 of 2 models passed, DeepSeek V4 Pro at $0.0006. The prompt in full.

   Claude Sonnet 5 passed this one and DeepSeek V4.1 Flash didn't. DeepSeek V4.1 Flash answered sooner (1.2 s to 2.7 s), and DeepSeek V4.1 Flash's reply cost less ($0.0003 to $0.0022); Claude Sonnet 5 wrote 105 tokens of reply, DeepSeek V4.1 Flash 68.

   • Claude Sonnet 5

     Passed: Graded 4.7 of 5 on average (lowest 4).

     In Q3, teams worked together to focus more on customers' needs. This effort increased customer retention by 12% and reduced the rate of customer loss (churn) by 0.3 percentage points among large business clients. The company also adjusted the number of customer contact channels (like phone, email, and chat) to better manage workload and resources.

     597 tokens in, 105 out · 2.7 s · $0.0022 · 1 message on Pro · answered by anthropic/claude-sonnet-5 via Claude Platform on AWS · September 27, 2026

   • DeepSeek V4.1 Flash

     Failed: Graded 3.7 of 5 on average (lowest 3).

     In the third quarter, teams from across the company worked together on a project that put customers first. For our large business customers, retention rose 12%, and churn fell by 30 basis points. We also adjusted our channels — online, in-store, and other ways customers reach us — to use our resources more efficiently.

     459 tokens in, 129 out (61 of them reasoning) · 1.2 s · $0.0003 · 1 message on Pro · answered by deepseek/deepseek-v4.1-flash via Parasail · September 27, 2026

3. 3. Decline a meeting and offer two times

   Everyday. Claude: 5 of 5 models passed, Claude Haiku 4.5 the cheapest at $0.0010 · DeepSeek: 2 of 2 models passed, DeepSeek V4.1 Flash the cheapest at $0.0002. The prompt in full.

   Claude Sonnet 5 and DeepSeek V4.1 Flash both passed this one. Claude Sonnet 5 answered sooner (2.8 s to 3.1 s), and DeepSeek V4.1 Flash's reply cost less ($0.0002 to $0.0026); Claude Sonnet 5 wrote 149 tokens of reply, DeepSeek V4.1 Flash 127.

   • Claude Sonnet 5

     Passed: Graded 5.0 of 5 on average (lowest 5).

     Subject: Re: Vendor Demo – Wednesday 11:00
     
     Hi Tom,
     
     Thanks for the invite! Unfortunately, I have a board presentation at that time on Wednesday, so I won't be able to join.
     
     Would Thursday at 10:00 or Friday at 14:00 work instead? Happy to make either one work on my end.
     
     Let me know what suits you, and I'll get it on the calendar.
     
     Best,
     [Your Name]

     542 tokens in, 149 out · 2.8 s · $0.0026 · 1 message on Pro · answered by anthropic/claude-sonnet-5 via Claude Platform on AWS · September 27, 2026

   • DeepSeek V4.1 Flash

     Passed: Graded 5.0 of 5 on average (lowest 5).

     **Subject:** Re: Vendor demo — Wednesday 11:00
     
     Hi Tom,
     
     Thanks for the invitation to the vendor demo. Unfortunately, I can't make Wednesday at 11:00 — I'm presenting to the board at that time.
     
     I'd still like to join, though. Would either of these work instead?
     
     - Thursday at 10:00
     - Friday at 14:00
     
     Let me know which suits you, and I'll confirm. If neither works, feel free to send notes or a recording and I'll follow up.
     
     Thanks again for thinking of me.
     
     Best regards,
     [Your name]

     434 tokens in, 157 out (30 of them reasoning) · 3.1 s · $0.0002 · 1 message on Pro · answered by deepseek/deepseek-v4.1-flash via Parasail · September 27, 2026

4. 4. A product announcement with five rules

   Hard. Claude: 3 of 5 models passed, Claude Sonnet 5.5 the cheapest at $0.0030 · DeepSeek: 1 of 2 models passed, DeepSeek V4.1 Flash at $0.0004. The prompt in full.

   Claude Sonnet 5 and DeepSeek V4.1 Flash both passed this one. Claude Sonnet 5 answered sooner (4.5 s to 6.2 s), and DeepSeek V4.1 Flash's reply cost less ($0.0004 to $0.0035); Claude Sonnet 5 wrote 235 tokens of reply, DeepSeek V4.1 Flash 91.

   • Claude Sonnet 5

     Passed: Graded 4.3 of 5 on average (lowest 4).

     **Introducing the Nordvik 2 Desk Lamp**
     
     Meet the Nordvik 2, thoughtfully redesigned for how you actually work. Five-step dimming lets you fine-tune brightness for any task, from focused reading to ambient evening light. The 270-degree rotating arm adjusts to virtually any angle, giving you precise control over where light falls. USB-C charging means one cable does it all, keeping your desk clutter-free and compatible with everything else you own.
     
     Priced at €79, the Nordvik 2 brings premium design and functionality within easy reach. It begins shipping on 1 December, just in time to brighten your winter workspace.
     
     Ready to see how the right light changes the way you work?

     554 tokens in, 235 out · 4.5 s · $0.0035 · 1 message on Pro · answered by anthropic/claude-sonnet-5 via Claude Platform on AWS · September 27, 2026

   • DeepSeek V4.1 Flash

     Passed: Graded 4.3 of 5 on average (lowest 4).

     Introducing the Nordvik 2, a desk lamp built for the way you actually work. Five dimming steps take you from bright task light to a soft evening glow. The arm turns a full 270 degrees, so you can aim light exactly where it is needed. Recharging is simple, via USB-C. The Nordvik 2 costs €79 and ships on 1 December. Would you like to see how it looks on your desk?

     445 tokens in, 495 out (404 of them reasoning) · 6.2 s · $0.0004 · 1 message on Pro · answered by deepseek/deepseek-v4.1-flash via CoreWeave · September 27, 2026

5. 5. Argue both sides of free buses

   Hard. Claude: 2 of 5 models passed, Claude Haiku 4.5 the cheapest at $0.0014 · DeepSeek: 1 of 2 models passed, DeepSeek V4.1 Flash at $0.0003. The prompt in full.

   Claude Sonnet 5 and DeepSeek V4.1 Flash both passed this one. DeepSeek V4.1 Flash answered sooner (3.9 s to 6.6 s), and DeepSeek V4.1 Flash's reply cost less ($0.0003 to $0.0050); Claude Sonnet 5 wrote 401 tokens of reply, DeepSeek V4.1 Flash 160.

   • Claude Sonnet 5

     Passed: Graded 4.0 of 5 on average (lowest 4).

     Free buses would boost ridership, cut traffic congestion, and reduce emissions by encouraging drivers to switch to transit. Lower-income residents, who rely most heavily on public transportation, would benefit enormously from eliminated fare burdens, improving access to jobs, education, and healthcare. Free transit also simplifies operations, speeding boarding times and eliminating costly fare collection infrastructure. Cities that have tried this, like Kansas City, saw ridership increases and stronger community mobility, suggesting free buses are both an equity tool and a practical urban planning solution.
     
     However, fares provide crucial revenue that funds maintenance, expansion, and service reliability. Eliminating them shifts costs entirely onto taxpayers, straining budgets already stretched thin, potentially forcing service cuts elsewhere. Free buses often attract overcrowding without corresponding investment in more vehicles, degrading service quality for existing riders. Critics also note that the poorest riders may already receive subsidized passes, making universal free fares a regressive policy that primarily benefits wealthier occasional riders. Better targeted subsidies, they argue, would achieve equity goals more efficiently than blanket free fares citywide.

     518 tokens in, 401 out · 6.6 s · $0.0050 · 1 message on Pro · answered by anthropic/claude-sonnet-5 via Claude Platform on AWS · September 27, 2026

   • DeepSeek V4.1 Flash

     Passed: Graded 4.3 of 5 on average (lowest 4).

     Free buses work. They cut car trips, congestion, and carbon, and they help the riders who need them most. Boarding speeds up, so routes run faster and cheaper to operate. The cost is modest—often less than a parking garage or a lane widening—and downtown shops gain customers. A city that charges nothing at the farebox treats mobility as a right, not a fee.
     
     But somebody still pays. Fares cover a real slice of operating costs, and replacing them means higher taxes or cuts elsewhere—often taxes that hit the poor hardest. Most riders already pay, so the subsidy flows to everyone, including the comfortable. Crowding slows buses, driving away choice riders. Better to means-test discounts, keep service frequent, and spend scarce dollars where they move the most people.

     423 tokens in, 282 out (122 of them reasoning) · 3.9 s · $0.0003 · 1 message on Pro · answered by deepseek/deepseek-v4.1-flash via StreamLake · September 27, 2026

• Claude Fable 5.1 vs DeepSeek V4 Pro: 3 of 5 each; DeepSeek V4 Pro answered 2.7× sooner at the median and cost 38.7× less.

• Claude Fable 5.1 vs DeepSeek V4.1 Flash: Claude Fable 5.1 3 of 5, DeepSeek V4.1 Flash 4; DeepSeek V4.1 Flash answered 1.9× sooner at the median and cost 60.5× less.

• Claude Opus 5.5 vs DeepSeek V4 Pro: Claude Opus 5.5 4 of 5, DeepSeek V4 Pro 3; DeepSeek V4 Pro answered 3.7× sooner at the median and cost 41.4× less. Claude Opus 5.5 vs DeepSeek V4 Pro, on every job.

• Claude Opus 5.5 vs DeepSeek V4.1 Flash: 4 of 5 each; DeepSeek V4.1 Flash answered 2.7× sooner at the median and cost 64.7× less.

• Claude Sonnet 5.5 vs DeepSeek V4 Pro: Claude Sonnet 5.5 4 of 5, DeepSeek V4 Pro 3; they took about as long and DeepSeek V4 Pro cost 7.7× less.

• Claude Sonnet 5.5 vs DeepSeek V4.1 Flash: 4 of 5 each; Claude Sonnet 5.5 answered 1.3× sooner at the median and DeepSeek V4.1 Flash cost 12.0× less.

• Claude Sonnet 5 vs DeepSeek V4 Pro: Claude Sonnet 5 4 of 5, DeepSeek V4 Pro 3; DeepSeek V4 Pro answered 2.0× sooner at the median and cost 7.7× less. Claude Sonnet 5 vs DeepSeek V4 Pro, on every job.

• Claude Sonnet 5 vs DeepSeek V4.1 Flash: 4 of 5 each; DeepSeek V4.1 Flash answered 1.5× sooner at the median and cost 12.0× less.

• Claude Haiku 4.5 vs DeepSeek V4 Pro: Claude Haiku 4.5 4 of 5, DeepSeek V4 Pro 3; they took about as long and DeepSeek V4 Pro cost 2.5× less. Claude Haiku 4.5 vs DeepSeek V4 Pro, on every job.

• Claude Haiku 4.5 vs DeepSeek V4.1 Flash: 4 of 5 each; Claude Haiku 4.5 answered 1.4× sooner at the median and DeepSeek V4.1 Flash cost 4.0× less. Claude Haiku 4.5 vs DeepSeek V4.1 Flash, on every job.

Every Claude and DeepSeek reply above was checked the same way as every other model's, by the rules published with the prompts: how the writing prompts are scored, and each one in full.

• The lineups

  Claude: 5 models, Claude Fable 5.1, Claude Opus 5.5, Claude Sonnet 5.5, Claude Sonnet 5, and Claude Haiku 4.5. DeepSeek: 2 models, DeepSeek V4 Pro and DeepSeek V4.1 Flash.

• Price per message

  The least expensive Claude model is Claude Haiku 4.5 (250 messages a month on Pro); the least expensive DeepSeek model is DeepSeek V4.1 Flash (60 messages a day on Pro).

• Context window

  Claude goes up to 1M tokens (Claude Fable 5.1); DeepSeek up to 1.05M tokens (DeepSeek V4 Pro).

• Images and PDFs

  DeepSeek V4 Pro doesn't read images. DeepSeek V4 Pro and DeepSeek V4.1 Flash get a PDF's text rather than the file itself.

• On the Free plan

  Free's one-time trial of 5 messages covers Claude Sonnet 5.5, Claude Sonnet 5, Claude Haiku 4.5, DeepSeek V4 Pro, and DeepSeek V4.1 Flash. Paid plans have every model, with messages every month.

In llmwise, a message to Claude goes to its maker, Anthropic, or through OpenRouter when llmwise can't reach the maker directly. DeepSeek models are served only through OpenRouter, by endpoints that don't store or train on prompts. The Privacy Policy has the details.