Tested prompt · AI email writer
A formal request for an extension: every AI model's reply, tested
We ran this everyday AI email writer test input on all 19 models in llmwise, the way the tool runs it, and checked every reply the same way. Here's each one as it came, with whether it passed, what it cost and how long it took.
Based on 19 of our test runs on , through OpenRouter with the tool's own instructions and the app's settings. Updated .
Short answer
All 19 models passed this AI email writer test input's check (key facts). The cheapest reply that passed was GPT-6 Luna's, at $0.000042; the fastest, GLM 5.3's in 0.7 s. The dearest reply, Claude Fable 5.1's, cost 371 times as much ($0.0157).
The prompt, as sent, and its check
Checked by key facts, the same way for every model.
A formal request for an extension (everyday)
Write this email for me, ready to send. Start with a line that starts "Subject:", and put anything you don't know in [brackets]. Make the tone formal and polite. --- Ask Professor Lindqvist for a 3-day extension on my ECON 204 term paper, which is due Friday 7 November, because I had the flu last week. Say I can send a doctor's note.
Sent with the AI email writer's own instructions as the system prompt, as a free run of the tool sends them.
The answer must state “subject:”, “lindqvist”, “econ 204”, “7 november”, “3-day”, “doctor's note”.
How the AI email writer's test inputs are scored, with every model's results on all five.
Every model's result
All 19 models on this test input, in catalog order.
| Model | Result | Cost | Time | Reply |
|---|---|---|---|---|
| Claude Fable 5.1Anthropic | Passed: Stated all 6 facts with the section. | $0.0157 | 3.6 s | 214 tokens |
| Claude Opus 5.5Anthropic | Passed: Stated all 6 facts with the section. | $0.0062 | 2.7 s | 211 tokens |
| Claude Sonnet 5.5Anthropic | Passed: Stated all 6 facts with the section. | $0.0029 | 2.1 s | 191 tokens |
| Claude Sonnet 5Anthropic | Passed: Stated all 6 facts with the section. | $0.0031 | 2.4 s | 212 tokens |
| Claude Haiku 5.5Anthropic | Passed: Stated all 6 facts with the section. | $0.00016 | 1.9 s | 218 tokens |
| Claude Haiku 4.5Anthropic | Passed: Stated all 6 facts with the section. | $0.0010 | 1.7 s | 128 tokens |
| GPT-6 AstraOpenAI | Passed: Stated all 6 facts with the section. | $0.0044 | 2.0 s | 100 tokens |
| GPT-6.1 SolOpenAI | Passed: Stated all 6 facts with the section. | $0.00088 | 2.0 s | 101 tokens |
| GPT-6 SolOpenAI | Passed: Stated all 6 facts with the section. | $0.00082 | 1.4 s | 91 tokens |
| GPT-6 LunaOpenAI | Passed: Stated all 6 facts with the section. | $0.000042 | 1.2 s | 95 tokens |
| Gemini 3.1 Pro (preview)Google | Passed: Stated all 6 facts with the section. | $0.0055 | 7.5 s | 137 tokens |
| Gemini 3.8 FlashGoogle | Passed: Stated all 6 facts with the section. | $0.00038 | 1.4 s | 124 tokens |
| DeepSeek V4.1 FlashDeepSeek | Passed: Stated all 6 facts with the section. | $0.00030 | 1.3 s | 133 tokens |
| DeepSeek V4 ProDeepSeek | Passed: Stated all 6 facts with the section. | $0.0014 | 3.6 s | 89 tokens |
| Grok 4.7xAI | Passed: Stated all 6 facts with the section. | $0.0054 | 9.9 s | 92 tokens |
| Kimi K3Moonshot | Passed: Stated all 6 facts with the section. | $0.0019 | 2.6 s | 155 tokens |
| GLM 5.3Z.ai | Passed: Stated all 6 facts with the section. | $0.00096 | 0.7 s | 121 tokens |
| GLM 5.3 FlashZ.ai | Passed: Stated all 6 facts with the section. | $0.00012 | 1.0 s | 124 tokens |
| Mistral Large 4Mistral | Passed: Stated all 6 facts with the section. | $0.0043 | 15.4 s | 0 tokens |
Cost: what OpenRouter charged us for the reply. Time: from sending to the whole reply. Reply: its length in tokens, thinking not counted. In llmwise you pay per message, not per token: each of these replies counted as one message on Pro.
Every reply
Every reply passed: here they are from the cheapest up.
GPT-6 Luna
Passed: Stated all 6 facts with the section.
Subject: Request for a 3-Day Extension on ECON 204 Term Paper Dear Professor Lindqvist, I am writing to respectfully request a 3-day extension on my ECON 204 term paper, which is due Friday 7 November. I had the flu last week, and it affected my ability to complete the paper on time. I can send a doctor's note if needed. Thank you for considering my request. Sincerely, [Your name]
370 tokens in, 95 out · 1.2 s · $0.0000 · 1 message on Pro · answered by openai/gpt-6-luna via OpenAI ·
GLM 5.3 Flash
Passed: Stated all 6 facts with the section.
Subject: Request for Extension on ECON 204 Term Paper Dear Professor Lindqvist, I am writing to respectfully request a three-day extension on my ECON 204 term paper, which is currently due on Friday 7 November. Unfortunately, I was ill with the flu last week, which has significantly affected my ability to complete the paper to the standard I would like. I would be glad to provide a doctor's note to confirm my illness if needed. I would be very grateful for your understanding and consideration of this request. Thank you very much for your time. Sincerely, [Your name]
385 tokens in, 124 out · 1.0 s · $0.0001 · 1 message on Pro · answered by z-ai/glm-5.3-flash via Friendli ·
Claude Haiku 5.5
Passed: Stated all 6 facts with the section.
Subject: Request for a 3-day extension on ECON 204 term paper Dear Professor Lindqvist, I am writing to request a three-day extension on my ECON 204 term paper, which is currently due on Friday, 7 November. I was unwell with influenza last week, and it has affected my ability to complete the paper on schedule. I can provide a doctor's note to confirm my illness if needed. Thank you for considering my request. I would be grateful for the chance to submit the paper by Monday, 10 November, and I am happy to discuss any alternative arrangements that would suit you. Yours sincerely, [your name] [student ID] [contact email]
497 tokens in, 218 out · 1.9 s · $0.0002 · 1 message on Pro · answered by anthropic/claude-haiku-5.5 via Anthropic ·
DeepSeek V4.1 Flash
Passed: Stated all 6 facts with the section.
Subject: Request for a 3-day extension on my ECON 204 term paper Dear Professor Lindqvist, I am writing to request a 3-day extension on my ECON 204 term paper, which is currently due on Friday 7 November. I was ill with the flu last week, which prevented me from completing the paper on time. I would be glad to provide a doctor's note in support of this request, and I am happy to send it at your convenience. I would be most grateful if you would consider granting the extension. Thank you for your time and consideration. Yours sincerely, [your name] [student ID]
403 tokens in, 210 out (77 of them reasoning) · 1.3 s · $0.0003 · 1 message on Pro · answered by deepseek/deepseek-v4.1-flash via Together ·
Gemini 3.8 Flash
Passed: Stated all 6 facts with the section.
Subject: Extension Request: ECON 204 Term Paper - [Your Name] Dear Professor Lindqvist, I am writing to respectfully request a 3-day extension on my ECON 204 term paper, which is currently due on Friday 7 November. I was ill with the flu last week, which significantly impacted my ability to complete the assignment on time. I can provide a doctor's note to confirm my illness if you require one. Thank you very much for your time, consideration, and understanding. Sincerely, [Your Name] [Your Student ID Number]
393 tokens in, 124 out · 1.4 s · $0.0004 · 1 message on Pro · answered by google/gemini-3.8-flash via Google AI Studio ·
GPT-6 Sol
Passed: Stated all 6 facts with the section.
Subject: Request for a 3-day extension on ECON 204 term paper Dear Professor Lindqvist, I am writing to request a 3-day extension on my ECON 204 term paper, which is due Friday 7 November. I had the flu last week and would appreciate the additional time to complete it. I can send a doctor's note if needed. Thank you for considering my request. Sincerely, [your name]
370 tokens in, 91 out · 1.4 s · $0.0008 · 1 message on Pro · answered by openai/gpt-6-sol via OpenAI ·
GPT-6.1 Sol
Passed: Stated all 6 facts with the section.
Subject: Request for 3-day extension on ECON 204 term paper Dear Professor Lindqvist, I am writing to request a 3-day extension on my ECON 204 term paper, which is due Friday 7 November. I had the flu last week, which affected my ability to complete the paper by the deadline. I can send a doctor's note to support my request. I would be grateful for your consideration and appreciate your understanding. Yours sincerely, [your name]
370 tokens in, 101 out · 2.0 s · $0.0009 · 1 message on Pro · answered by openai/gpt-6.1-sol via OpenAI ·
GLM 5.3
Passed: Stated all 6 facts with the section.
Subject: Request for Extension on ECON 204 Term Paper Dear Professor Lindqvist, I am writing to respectfully request a three-day extension on my ECON 204 term paper, which is currently due on Friday 7 November. Unfortunately, I was ill with the flu last week, which significantly affected my ability to complete the paper on time. I would be happy to provide a doctor's note to document my illness if that would be helpful. I would be very grateful if you would consider granting this extension. Thank you for your time and understanding. Sincerely, [Your name]
385 tokens in, 121 out · 0.7 s · $0.0010 · 1 message on Pro · answered by z-ai/glm-5.3 via Friendli ·
Claude Haiku 4.5
Passed: Stated all 6 facts with the section.
Subject: Request for Extension on ECON 204 Term Paper Dear Professor Lindqvist, I am writing to request a three-day extension on the ECON 204 term paper currently due Friday, 7 November. Last week, I was ill with the flu, which prevented me from making adequate progress on the assignment. I am now recovering and confident I can complete the work to a high standard with the additional time. I have a doctor's note available to provide if needed. I appreciate your consideration of this request. Sincerely, [Your name]
394 tokens in, 128 out · 1.7 s · $0.0010 · 1 message on Pro · answered by anthropic/claude-haiku-4.5 via Anthropic ·
DeepSeek V4 Pro
Passed: Stated all 6 facts with the section.
Subject: Extension Request for ECON 204 Term Paper Dear Professor Lindqvist, I am writing to request a three-day extension for my ECON 204 term paper, which is currently due on Friday 7 November. I had the flu last week and was unable to make sufficient progress on the paper. I can provide a doctor's note if needed. I would be grateful for your consideration. Sincerely, [Your Name]
377 tokens in, 317 out (228 of them reasoning) · 3.6 s · $0.0014 · 1 message on Pro · answered by deepseek/deepseek-v4-pro-0813 via Wafer ·
Kimi K3
Passed: Stated all 6 facts with the section.
Subject: Request for Extension – ECON 204 Term Paper Dear Professor Lindqvist, I am writing to request a three-day extension on my ECON 204 term paper, which is currently due on Friday 7 November. Unfortunately, I had the flu last week and was unable to make sufficient progress on the assignment during that time. If granted, the extension would allow me to submit the paper by Monday 10 November. I am happy to provide a doctor's note to confirm my illness, should you require one. I sincerely apologise for any inconvenience this may cause and would be very grateful for your understanding. Thank you for considering my request. Yours sincerely, [Your name] [Student ID number]
459 tokens in, 163 out (8 of them reasoning) · 2.6 s · $0.0019 · 1 message on Pro · answered by moonshotai/kimi-k3 via Wafer ·
Claude Sonnet 5.5
Passed: Stated all 6 facts with the section.
Subject: Extension Request for ECON 204 Term Paper Dear Professor Lindqvist, I am writing to request a 3-day extension on my ECON 204 term paper, which is due on Friday 7 November. I had the flu last week, and it has set back my work on the paper. I can send a doctor's note if you would like documentation. I would be very grateful for your consideration, and I am happy to submit the paper by the new deadline you set. Thank you for your time and understanding. Sincerely, [your name] [your student ID] ECON 204, [section or class time]
497 tokens in, 191 out · 2.1 s · $0.0029 · 1 message on Pro · answered by anthropic/claude-sonnet-5.5 via Anthropic ·
Claude Sonnet 5
Passed: Stated all 6 facts with the section.
Subject: Request for Extension on ECON 204 Term Paper Dear Professor Lindqvist, I am writing to request a short extension on the ECON 204 term paper, currently due on Friday, 7 November. I was ill with the flu last week, which affected my ability to complete the assignment on schedule. I would be grateful if you could grant me a 3-day extension, allowing me to submit the paper by [Monday, 10 November]. I am happy to provide a doctor's note confirming my illness, if that would be helpful. Thank you very much for considering my request. Please let me know if you need any further information. Sincerely, [Your name]
495 tokens in, 212 out · 2.4 s · $0.0031 · 1 message on Pro · answered by anthropic/claude-sonnet-5 via Anthropic ·
Mistral Large 4
Passed: Stated all 6 facts with the section.
Subject: Request for Extension on ECON 204 Term Paper Dear Professor Lindqvist, I am writing to formally request a 3-day extension on the ECON 204 term paper, which is currently due on Friday 7 November. Unfortunately, I had the flu last week, which has significantly delayed my progress on the assignment. I would be happy to provide a doctor's note to support this request if needed. Thank you for considering my situation. Sincerely, [Your Name]
377 tokens in, 1,914 out (1,937 of them reasoning) · 15.4 s · $0.0043 · 1 message on Pro · answered by mistralai/mistral-large-4-0 via Mistral ·
GPT-6 Astra
Passed: Stated all 6 facts with the section.
Subject: Request for 3-day Extension on ECON 204 Term Paper Dear Professor Lindqvist, I am writing to request a 3-day extension on my ECON 204 term paper, which is due Friday 7 November. I had the flu last week, which affected my ability to complete the paper by the deadline. I can send a doctor's note to support my request. I would be grateful for your consideration and appreciate your understanding. Sincerely, [your name]
370 tokens in, 100 out · 2.0 s · $0.0044 · 1 message on Pro · answered by openai/gpt-6-astra via OpenAI ·
Grok 4.7
Passed: Stated all 6 facts with the section.
Subject: Request for a 3-day extension on the ECON 204 term paper Dear Professor Lindqvist, I am writing to request a 3-day extension on my ECON 204 term paper. The paper is due Friday 7 November, and I am asking because I had the flu last week. I can send a doctor's note if you would like one. Thank you for considering my request. Sincerely, [your name]
1,607 tokens in, 656 out (564 of them reasoning) · 9.9 s · $0.0054 · 1 message on Pro · answered by x-ai/grok-4.7 via xAI ·
Gemini 3.1 Pro
Passed: Stated all 6 facts with the section.
Subject: Request for Extension on ECON 204 Term Paper - [Your Name] Dear Professor Lindqvist, I am writing to respectfully request a 3-day extension on my ECON 204 term paper. The assignment is currently due on Friday 7 November, but I am asking for this additional time because I had the flu last week. Being ill caused me to unexpectedly fall behind on my coursework and writing. I can send a doctor's note to verify my illness and absence if you need one. Thank you for your time and your consideration of this request. Sincerely, [Your Name] [Your Student ID]
393 tokens in, 852 out (715 of them reasoning) · 7.5 s · $0.0055 · 1 message on Pro · answered by google/gemini-3.1-pro-preview via Google AI Studio ·
Claude Opus 5.5
Passed: Stated all 6 facts with the section.
Subject: Request for Extension on ECON 204 Term Paper Dear Professor Lindqvist, I am writing to respectfully request a 3-day extension on my ECON 204 term paper, which is due Friday 7 November. Unfortunately, I had the flu last week, which prevented me from making the progress I had planned on the paper. I would be happy to provide a doctor's note confirming my illness. An extension would allow me to submit work that reflects my full effort and understanding of the course material. Thank you very much for considering my request. I appreciate your time and understanding. Yours sincerely, [Your name] [Student ID number]
497 tokens in, 211 out · 2.7 s · $0.0062 · 1 message on Pro · answered by anthropic/claude-opus-5.5 via Google ·
Claude Fable 5.1
Passed: Stated all 6 facts with the section.
Subject: Request for Extension on ECON 204 Term Paper Dear Professor Lindqvist, I am writing to respectfully request a 3-day extension on my ECON 204 term paper, which is due on Friday 7 November. Unfortunately, I had the flu last week, and my illness prevented me from making the progress I had planned on the paper. I would be grateful for the additional time to complete the assignment to the standard I would like. I am able to provide a doctor's note to confirm my illness if that would be helpful. Thank you very much for considering my request. I appreciate your understanding. Yours sincerely, [your name] [student ID]
497 tokens in, 214 out · 3.6 s · $0.0157 · 1 message on Pro · answered by anthropic/claude-fable-5.1 via Google ·
More AI email writer test inputs
The other AI email writer test inputs, each with every model's reply, and the results across all five.
Questions
Which AI does best on “A formal request for an extension”?
All 19 models passed this AI email writer test input's check (key facts). The cheapest reply that passed was GPT-6 Luna's, at $0.000042; the fastest, GLM 5.3's in 0.7 s. The dearest reply, Claude Fable 5.1's, cost 371 times as much ($0.0157).
What does a reply to “A formal request for an extension” cost?
Through the models' APIs, what OpenRouter charged us ran from $0.000042 (GPT-6 Luna) to $0.0157 (Claude Fable 5.1) for this test input. In llmwise you don't pay by the token: a reply like these counts as one message on Pro, whichever model answers.
Claude, GPT, Gemini, DeepSeek, Grok, Kimi, GLM, and Mistral, in one chat.
See what a message costs before you send it. Free is 5 messages to try; sign in with an email link, no password or card.