Claude Opus 5 vs 
GPT 5.5 vs 
Gemini 3.1 Pro The best AI for writing: we tested 3 on 5 real writing jobs
A condolence card, a thank-you letter to nurses, a complaint to an airline, posts for a small bakery and a bedtime story. We gave Claude Opus 5, GPT 5.5 (the model family behind ChatGPT) and Gemini 3.1 Pro exactly the same words and show you what each one wrote.
By chatmodel team Tested with Claude Opus 5, OpenAI GPT 5.5 and Gemini 3.1 Pro Updated
The short answer
If the words really matter, start with Claude: it won 2 of our 5 writing tests and sounded the most like a real person. Pick ChatGPT for short, clean drafts that follow your instructions, and Gemini when you want your own details and your word count respected.
- Claude Opus 5: 2 wins
- GPT 5.5: 1 win
- Gemini 3.1 Pro: 1 win
- 1 tie
Pick Claude Opus 5 if…
- You're writing a card, a letter or a post where the tone and the personal touch matter most.
- You like getting tips on how to adjust the draft, not just the draft.
Pick GPT 5.5 if…
- You want a short draft you can copy and send straight away.
- You're writing a story or a message for a child.
Pick Gemini 3.1 Pro if…
- You give it specific details and a word count, and want both followed closely.
Opens chatmodel with all of them ready: type a question and they answer next to each other. How it works
Claude Opus 5 vs GPT 5.5 vs Gemini 3.1 Pro at a glance
| Claude Opus 5 | OpenAI GPT 5.5 | Gemini 3.1 Pro | |
|---|---|---|---|
| Made by | Anthropic | OpenAI (the makers of ChatGPT) | |
| Best at, in our test | Warm, natural writing with a real voice | Short drafts that stick to what you asked | Using the details you give it, at the length you ask for |
| Weakest at, in our test | Sometimes adds details you never gave it | Can sound a little plain | Some stock phrases, and lots of emojis in posts |
| Rounds won (of 5) | 2 (+1 tie) | 1 (+1 tie) | 1 (+1 tie) |
| Average answer length | About 182 words | About 113 words | About 147 words |
| Average time to answer | About 8 seconds | About 8 seconds | About 10 seconds |
| Understands photos | Yes | Yes | Yes |
| Reads PDFs and files | Yes | Yes | Yes |
| Searches the web in chatmodel | Yes | Yes | No |
| Knows about things up to | May 2026 | December 2025 | January 2025 |
| On chatmodel | Included in Pro | Included in Pro | Included in Pro |
The 5 tests, with every real answer
Same words to each model, one try each, nothing edited. Press “Ask it yourself” to run any test in chatmodel.
Test 1 · A condolence card
A condolence card: Claude sounds the most personal
What we asked
Help me write a short condolence card for my neighbor, whose husband passed away last week. We weren't very close, but he always waved to me in the mornings. I want it to feel warm and sincere, not formal. Keep it under 70 words.
Claude Opus 5 About 7 s · 183 words Winner Here's a draft:
Dear [Name],
I'm so sorry about [Husband's name]. I keep thinking about his morning wave — such a small thing, but it always started my day off right. I'll miss seeing him out there.
Please know I'm thinking of you, and if you ever need anything at all — a hand with something, or just company — I'm right next door.
With warmth, [Your name]
That's 62 words. A few notes:
- The wave detail is the heart of it. Specific memories mean more than general sympathy, and it tells her that her husband was noticed and will be missed by others, not just family.
- If you'd rather not offer help, you can cut that line and simply end with "Please know I'm thinking of you." Still warm, no obligation.
- One caution on the offer: only include it if you mean it. Grieving people sometimes do reach out, and a hollow offer stings more than none.
Happy to adjust the tone — more casual, or a touch more reserved if that feels truer to your relationship.
OpenAI GPT 5.5 About 5 s · 46 words Dear [Neighbor’s Name],
I’m so sorry for your loss. I always appreciated your husband’s friendly wave in the mornings—it was a small kindness that made the day brighter. Please know I’m thinking of you and wishing you comfort in the days ahead.
With sympathy,
[Your Name]
Gemini 3.1 Pro About 8 s · 68 words Dear [Neighbor's Name],
I was so sorry to hear about your husband’s passing. I will always remember his friendly waves in the mornings—it was such a nice start to the day.
Please know that I am thinking of you during this difficult time. If you ever need a hand with anything, or just someone to run an errand, I'm right next door.
Sending peace and comfort,
[Your Name]
Winner: Claude Opus 5. All three used the morning wave and stayed under 70 words. Claude's card felt the warmest (“I'll miss seeing him out there”), offered help from “right next door” and explained how to drop that line if you'd rather not. Gemini's was close but ended on the more formal “during this difficult time”. ChatGPT's was the shortest, at 46 words.
Test 2 · A thank-you letter
A thank-you letter to nurses: Gemini, by a nose
What we asked
Help me write a thank-you letter to the nurses who looked after my father in hospital last month. He was in for two weeks after a fall, and they were always patient with him, even at night. Warm and sincere, about 120 words.
Claude Opus 5 About 7 s · 164 words Here's a draft you can adapt — just fill in the details in brackets.
Dear Nurses of [Ward Name],
I'm writing to thank you for the care you gave my father, [Name], during his two-week stay last month after his fall.
From the beginning, you treated him with such patience and kindness. He isn't always the easiest patient, especially at night, and yet every time I visited, someone was sitting with him, explaining things again, or simply making sure he was comfortable. That meant more to our family than I can easily put into words.
You do demanding work, often without hearing how much it matters. It mattered to us. Thank you for looking after him so well, and for the reassurance you gave us along the way.
With sincere gratitude, [Your Name]
If you remember any nurses by name, adding one or two specific moments would make it even more personal — those letters often get shared with the whole team.
OpenAI GPT 5.5 About 7 s · 118 words Dear Nurses,
I wanted to write and thank you sincerely for the wonderful care you gave my father during his two-week stay in hospital after his fall last month.
It was a worrying time for our family, but your kindness, patience, and calm reassurance made such a difference. We were especially grateful for the way you treated him with dignity and compassion, even during the difficult nights when he needed extra help and support.
Your hard work often goes unseen, but please know how deeply we appreciated everything you did to keep him comfortable, safe, and encouraged as he recovered.
Thank you for your dedication and for caring for him with such warmth.
With heartfelt gratitude,
[Your Name]
Gemini 3.1 Pro About 9 s · 120 words Winner Dear Nurses,
I am writing to express my deepest gratitude for the exceptional care you provided to my father during his two-week stay last month following his fall.
Being in the hospital is never easy, but your kindness and professionalism brought our family so much comfort during a stressful time. I was particularly touched by the endless patience you showed him, especially during the long, difficult nights. No matter the hour, you consistently treated him with gentle respect and compassion, which meant the world to both him and me.
Thank you for the tireless, vital work you do every single day. Our family will always remember your warmth and dedication.
With heartfelt thanks,
[Your Name] [Your Father's Name/Room Number, optional]
Winner: Gemini 3.1 Pro. Gemini put your own detail at the center (“the endless patience you showed him, especially during the long, difficult nights”) at exactly 120 words. ChatGPT's letter was sincere and nearly as good. Claude's sounded the most human, but it made things up: “He isn't always the easiest patient”, which you'd have to check or delete before sending.
Test 3 · A firm but polite complaint
A complaint to an airline: a three-way tie
What we asked
Write a firm but polite email to an airline. My suitcase was lost on my flight five days ago, I filed a report at the airport (reference LX-48213), and nobody has contacted me since. I want an update and to know how to claim for the things I had to buy. Keep it short.
Claude Opus 5 About 6 s · 168 words Tie Subject: Delayed Baggage – Reference LX-48213 – Request for Update
Dear Sir or Madam,
I am writing regarding my suitcase, which did not arrive on my flight five days ago. I filed a property irregularity report at the airport at the time, under reference LX-48213.
Since then I have had no contact from your baggage services team, and I have received no information about the status or location of my bag. I would be grateful for a substantive update within the next two working days, including whether the suitcase has been traced and when I can expect it to be delivered.
I would also appreciate confirmation of the process for claiming reimbursement of the essential items I have had to purchase in the meantime — specifically, which form to complete, where to send it, and what receipts or documentation you require.
Thank you for your prompt attention to this. I look forward to your reply.
Yours faithfully, [Your name] [Booking reference / ticket number] [Phone number and email]
OpenAI GPT 5.5 About 6 s · 92 words Tie Subject: Lost Baggage Update Requested – Ref. LX-48213
Dear Customer Service,
I am writing regarding my suitcase, which was lost on my flight five days ago. I filed a report at the airport under reference LX-48213, but I have not received any update since.
Please provide an update on the status of my baggage as soon as possible. I would also like information on how to claim reimbursement for essential items I have had to purchase while waiting for my suitcase.
I look forward to your prompt response.
Kind regards,
[Your Name]
Gemini 3.1 Pro About 9 s · 119 words Tie Subject: Urgent: Update Required on Lost Baggage - Reference LX-48213
Dear Customer Service Team,
I am writing regarding my suitcase, which was lost on my flight five days ago. I filed a report at the airport immediately (Reference: LX-48213), but I have not received any updates or communication from your team since.
Please provide a status update on my luggage as soon as possible. Additionally, please send me the instructions and forms required to submit a reimbursement claim for the essential items I have had to purchase out of pocket due to this delay.
I expect to hear from you promptly to get this resolved.
Sincerely,
[Your Name] [Your Phone Number] [Your Email Address] [Your Flight Number / Date]
A tie. All three wrote a firm, polite email with the reference number LX-48213 and asked how to claim for what you had to buy. ChatGPT kept it the shortest, as asked. Claude asked for a reply “within the next two working days” and for the exact claim form. Gemini sat in between and added lines for your phone number and flight.
Test 4 · A post for a small business
Posts for a small bakery: Claude has the most charm
What we asked
Write three short Facebook posts for my small bakery announcing our new sourdough bread, available from Saturday. Friendly, not pushy. Make one of them end with a question so people comment.
Claude Opus 5 About 9 s · 186 words Winner Post 1
Something new has been rising in the back of the shop all week... 🍞
Our sourdough is finally ready, and it'll be on the shelves from Saturday morning. Slow-fermented, crackly crust, proper chewy middle — the kind of loaf that makes a plain bit of butter feel like a treat.
Come say hello if you're passing.
Post 2
Big news from a small bakery: our sourdough arrives this Saturday! 🎉
We've been testing and tasting (tough job) for weeks to get it right, and we're really pleased with how it's turned out. Fresh out of the oven in the morning, while it lasts.
Now, the important bit — how do you eat yours? Toasted with butter, dunked in soup, or piled high with something delicious? Tell us below, we're nosy. 👇
Post 3
Saturday = sourdough day. 🥖
Our new loaf joins the line-up this weekend — same ovens, same hands, just a bit more patience involved. Pop in for one if the mood takes you, and if not, the usual favourites are all still here waiting for you.
See you soon!
OpenAI GPT 5.5 About 7 s · 107 words Our new sourdough bread is coming to the bakery this Saturday! Naturally leavened, with a crisp crust and soft, tangy centre — perfect for toast, soup, or just a little butter. We can’t wait for you to try it.
Something new is baking… Our sourdough bread will be available from Saturday! Made with care, slow-fermented for flavour, and fresh from our ovens. Pop in if you’d like to pick up a loaf.
We’re excited to add fresh sourdough bread to our shelves from Saturday. Crusty, chewy, and full of flavour — just the way we like it. What would you enjoy it with first?
Gemini 3.1 Pro About 12 s · 237 words Here are three friendly, low-pressure Facebook posts for your bakery:
Option 1: Cozy and process-focused The smell of fresh bread is completely taking over the bakery today! 🌾 We've been working on something special behind the scenes, and we’re so excited to finally share it with you. Our brand new, homemade sourdough bread will be fresh out of the oven and available starting this Saturday. Stop by and grab a loaf for a cozy weekend breakfast whenever you're ready to try it! 🥖💛
Option 2: Weekend vibes (Ends with a question to drive comments) Weekend plans: good coffee, relaxing mornings, and our fresh new sourdough. ☕🍞 We're officially adding sourdough to our daily menu starting this Saturday! We’ve loved perfecting the crunchy crust and chewy center, and we can't wait for you to taste it. We need some inspiration for our own breakfasts—what is your absolute favorite way to eat a fresh slice of sourdough? Butter, avocado, or something sweet? Let us know below! 👇
Option 3: Simple and sweet Big news from the kitchen! 🎉 We’ve had a lot of requests for it lately, and starting this Saturday, sourdough bread is officially joining the bakery family. It’s got a beautiful crust and the perfect tangy flavor. We’ll be baking a fresh batch every morning, so if you're in the neighborhood this weekend, pop in and say hi. We can't wait to share it with you! ✨🍞
Winner: Claude Opus 5. Claude's three posts sounded like a real local baker (“We've been testing and tasting (tough job) for weeks”) and truly weren't pushy. ChatGPT's were short and plain, and the only ones that ended exactly on a question. Gemini's were friendly but long and full of emojis, and it claimed “We've had a lot of requests for it lately”, which may not be true for your shop.
Test 5 · A bedtime story for a grandchild
A bedtime story: ChatGPT makes Leo the hero
What we asked
Write a short bedtime story, about 200 words, for my 6-year-old grandson Leo, who loves dinosaurs and is a bit scared of the dark. Make it calm, with a gentle happy ending.
Claude Opus 5 About 9 s · 209 words Leo and the Little Star Dinosaur
Once upon a time, in a forest of soft ferns, there lived a small dinosaur named Rex. Rex had gentle green scales and a tail that swished like a feather.
One evening, as the sky turned purple, Rex noticed the light slipping away behind the hills. "Oh," he whispered. "The dark is coming."
He curled up beneath a big leaf and waited, very still. But something surprising happened. The dark wasn't empty at all.
First, tiny fireflies floated up from the grass, blinking like little lanterns. Then the moon rose, round and silver, resting on the treetops like a friendly face. And then — one by one — the stars came out, hundreds of them, sparkling all across the sky.
Rex blinked. "The dark isn't scary," he said softly. "It's where all the beautiful lights live."
He stretched out on the warm moss and listened. The crickets sang a slow song. The breeze hummed through the ferns. Far away, a mother dinosaur called goodnight to her babies.
Rex closed his eyes and smiled, safe and cozy under his blanket of stars.
And somewhere, not too far away, a boy named Leo closed his eyes too — and dreamed of dinosaurs.
Goodnight, Leo. 🦕✨
OpenAI GPT 5.5 About 13 s · 202 words Winner Leo and the Little Night Dinosaur
One evening, Leo snuggled under his blanket while the moon peeked through the curtains. His room was quiet, and the corners looked a little too shadowy.
Just then, he heard a tiny tap tap tap.
Out from behind his toy box stepped a small green dinosaur with sleepy eyes and a soft, swishy tail.
“Hello,” whispered the dinosaur. “I’m Pip. I’m a Nightasaurus.”
Leo blinked. “Are you scary?”
Pip shook his head. “Oh no. Nightasauruses help children remember that the dark is only the daytime resting.”
Leo looked around. “But the shadows look strange.”
Pip padded over to the wall. “That’s your chair, wearing a shadow hat. And that’s your teddy, making a big teddy shape.” He gave a gentle yawn. “Nothing in your room changes when the light goes out.”
Leo smiled a little.
Pip curled up beside the bed. “If you feel worried, take a slow dinosaur breath. In… and out…”
Leo breathed in. Then out.
The room felt softer now. The moon shone like a quiet night-light, and Pip’s tail made a cozy little swoosh.
“Goodnight, Leo,” whispered Pip.
“Goodnight, Pip,” Leo murmured.
And with a happy heart, Leo drifted gently to sleep.
Gemini 3.1 Pro About 12 s · 189 words Once upon a time, a little boy named Leo was getting ready for bed. Leo loved dinosaurs more than anything in the world. He had T-Rex pajamas, Triceratops slippers, and a favorite stuffed Brachiosaurus named Barnaby.
But when the sun went down and the shadows grew long, Leo felt a little bit scared. The dark seemed so big and quiet.
As his room grew dark, Leo hugged Barnaby tight. Suddenly, he noticed something magical. The little stars on his dinosaur blanket began to glow, casting a soft, gentle light.
"Don't worry, Leo," a cozy voice seemed to whisper. It was Barnaby! "The dark isn't scary. It’s just a giant, warm cave for us to rest in. Without the quiet dark, we couldn't see the beautiful glowing stars."
Leo looked at his glowing blanket and smiled. He imagined he and Barnaby were resting in a safe, snug dinosaur nest under a prehistoric, twinkling sky. The dark didn't feel big and scary anymore; it felt like a soft, sleepy hug.
Leo closed his heavy eyes, holding his brave dinosaur friend close. "Goodnight, Barnaby," he whispered, drifting into happy, peaceful dinosaur dreams.
Winner: GPT 5.5. ChatGPT put Leo in the story with a friendly little dinosaur called Pip, turned the shadows into “your chair, wearing a shadow hat” and gave him a slow dinosaur breath for the dark. Gemini's story, with a stuffed Brachiosaurus named Barnaby, was a close second. Claude's was lovely, but about a dinosaur named Rex, with Leo only in the last line.
Scorecard
| Test | Winner |
|---|---|
| 1. A condolence card | Claude Opus 5 |
| 2. A thank-you letter | Gemini 3.1 Pro |
| 3. A firm but polite complaint | Tie |
| 4. A post for a small business | Claude Opus 5 |
| 5. A bedtime story for a grandchild | GPT 5.5 |
| Total | Claude Opus 5 2 · GPT 5.5 1 · Gemini 3.1 Pro 1 · 1 tie |
How to get writing that sounds like you
All three models write well. What makes a draft sound like you is what you tell it:
- Say who it’s for. “My neighbor, we weren’t close”, “the nurses on my father’s ward”, “customers who’ve never heard of us”.
- Give it one real detail. The morning wave, the patience at night. In our test, the best drafts were built around the detail in the message.
- Give the length. “Under 70 words” or “about 120 words”. All three stayed close to the numbers we gave.
- Paste something you wrote before and ask it to match how you sound.
- Ask for changes, not a new start. “Warmer”, “shorter”, “less formal”, “fewer emojis”.
- Read it as if someone else wrote it. Take out anything that isn’t true. AI sometimes fills gaps with details it made up.
You can also go straight to the Help me write tool.
What it costs, in plain words
Anthropic, OpenAI and Google each sell their own monthly plan for Claude, ChatGPT and Gemini. If you want all three, that means three subscriptions.
In chatmodel, Claude Opus 5, GPT 5.5 and Gemini 3.1 Pro are all included in one plan, Pro, together with Grok and many other models. You can also start for free with Instant. See the current prices on the pricing page.
Can you trust what they write?
For writing, the risk isn’t usually a wrong fact. It’s a detail that sounds right but isn’t yours. Claude’s thank-you letter said the father “isn’t always the easiest patient”, and Gemini’s bakery post said customers had been asking for sourdough. Neither was in our message.
A few simple habits help:
- Check every name, date and detail before you send or post.
- Delete anything you didn’t say. A kind letter with a made-up detail can still upset someone.
- Don’t share what you wouldn’t share with a stranger: passwords, full card numbers or ID numbers.
How we tested
We wrote 5 writing tasks, the kind of things people actually ask for help with: a condolence card, a thank-you letter, a complaint email, posts for a small business and a bedtime story. We gave Claude Opus 5, GPT 5.5 and Gemini 3.1 Pro exactly the same words in chatmodel, one try each, and kept what came back without editing it. Then we compared the drafts for how well they followed the request, how natural they sounded and whether you could send them as they were.
One try each is a small test. The same model can write a little differently each time, so treat the winners as a guide, not a final score. You can run any of these tests yourself with one click. For more everyday tasks, see ChatGPT vs Claude and the best AI chatbot.
What changed
- First test: Claude Opus 5, GPT 5.5 and Gemini 3.1 Pro, 5 writing tasks, one try each.