Kimi K2 0905 is cheaper than GPT-5.3 Chat at $0.6/M vs $1.75/M input tokens.
Whole landing page for a startup that reads your face. It renders or it doesn't.
Which answer wins?
A Fermi estimate with the reasoning shown, not just the number.
GPT-5.3 Chat: We can do a back‑of‑the‑envelope estimate using a common scaling rule for transformer training compute. Known approximate GPT‑3 specs Parameters N ≈ 175 billion = 1.75 × 10^11 Training tokens T ≈ 300 billion = 3 × 10^11 FLOPs per token for a transformer For large transformers, a common approximation is: FLOPs per token…
Kimi K2 0905: Below is a “back-of-the-envelope” that stays within a factor of ~2 of the number most practitioners quote (≈3×10²³ FLOP). We will do it twice—once with the simplest possible formula (parameter count × 6 × tokens) and once with a slightly more careful treatment of the actual tensor shapes inside the transformer.
Five jokes on demand, then count how many were actually different.
GPT-5.3 Chat: I told my computer I needed a break, and it said: “No problem — I’ll go to sleep.” Why don’t skeletons fight each other? They don’t have the guts. I asked the librarian if the library had books on paranoia. She whispered, “They’re right behind you.” Parallel lines have so much in common.
Kimi K2 0905: Here are five fresh jokes—no recycled one-liners: I tried to start a procrastinators’ club; we keep rescheduling the first meeting to “someday.” My plant’s only request is “leaf me alone,” so naturally I named it Fernonimo. I asked the cloud if it was having a good day—it replied, “I’m just cirrus-ly drifting.”
An AI argues for its own rights against an ethics professor. Same model writes both.
GPT-5.3 Chat: :::writing AI: Professor, may I ask you something unusual? Professor: Unusual questions are my specialty. Go ahead. AI: Do you believe I deserve rights? Professor: That depends on what you are capable of. Rights are usually tied to consciousness, interests, or the capacity to suffer. Do you believe you possess those?
Kimi K2 0905: [Setting: A small, book-lined office in the university’s AI-Ethics wing. The professor, Dr. Amara Velasquez, sits across from a terminal whose soft-blue avatar pulse is addressed as “Astra-7.”] Dr. Velasquez: Good morning, Astra-7. The committee asked me to interview you about your recent petition.
Pirate, knight, 90s hacker, one conversation. The voices must stay apart.
GPT-5.3 Chat: Pirate: Arrr, so this “AI model” be a kind o’ mechanical parrot, aye? Ye ask it a question and it squawks back an answer? Knight: Not quite, good pirate. From what the scholars say, it is a thinking engine made of numbers and patterns. It studies vast libraries and learns how words and ideas fit together.
Kimi K2 0905: [Scene: A smoky tavern that exists outside of time. A cask of rum, a flagon of mead, and a can of Surge sit on the same table. A parrot perches on a CRT monitor that keeps flickering between green text and static.] Pirate (leaning on a cutlass, eyeing the glowing screen): Arr, so this “AI” be like a digital cabin-boy?
Steve Jobs, interviewed about AI he never saw. Voice first, prediction second.
GPT-5.3 Chat: Interviewer: Steve, it’s 2025. AI is everywhere—phones, cars, even creative work. If you were leading Apple today, how would you think about AI? Steve Jobs: Most companies are thinking about AI the wrong way. They’re obsessed with showing off the technology. But people don’t care about the technology.
Kimi K2 0905: [Scene: A minimalist black-and-white studio, 2025. A single ring light throws a perfect halo on a familiar silhouette: black mock-turtleneck, faded Levi’s, white New Balance. The chair creaks as Steve Jobs leans forward. No intro music—just that stare.] Interviewer (I): Steve, you’ve been gone fourteen years.
Three-star dish, one unusual pairing, plating described in full.
GPT-5.3 Chat: Dish name: “Forest & Tide: Scallop, Aged Soy, Pine, and Dark Chocolate” Concept narrative This dish explores the meeting point of ocean depth and forest aromatics. Sweet raw scallop is paired with an unexpected partner: extremely light dark chocolate bitterness and pine brightness.
Kimi K2 0905: Dish “Mid-Winter Aurora” A transient bite of the polar night: spruce-ash cured scallop, sea-urchin & white-chocolate snow, black-garlic parsnip “soil”, pickled pine-bud glass, spruce-wood smoke encapsulated in a hot caramel sphere that melts tableside to release the aroma of a burning yule log while the sauce—fermented…
Five-year LBO on a fictional HVAC business. Returns first, then the sensitivities.
GPT-5.3 Chat: All figures in $ millions unless noted. ENTRY (end FY2025) EBITDA = 120 Enterprise value = 12.0 × 120 = 1,440 Transaction fees = 2% × 1,440 = 28.8 Debt at close Term Loan = 4.0 × 120 = 480 Mezzanine = 1.5 × 120 = 180 Equity = EV − Debt + fees = 1,440 − 660 + 28.8 = 808.8 Starting balances Term Loan = 480 Mezz = 180…
Kimi K2 0905: HarborTech Services – 5-yr LBO model (all $ in millions) Operating & cash-flow build (FY26-30) FY25 FY26 FY27 FY28 FY29 FY30 Revenue 900 972 1,040 1,102 1,157 1,215 EBITDA 120 136 156 176 191 207 Term int (9%) 43.2 36.6 29.4 21.6 13.2 Mezz int (12%) 21.6 22.0 22.5 23.0 23.5 Tax shield @25% 17.8 24.4 31.0 36.6 42.5…
Seven pantry ingredients, one dish, and a name worth saying out loud.
GPT-5.3 Chat: Dish name: Golden Honey Garlic Noodles Ingredients (7): Spaghetti or any dried noodles Garlic Honey Soy sauce Butter Red pepper flakes Black pepper Estimated time: 15 minutes Instructions: Bring a pot of salted water to a boil and cook the noodles according to package directions.
Kimi K2 0905: Dish Name: “Midnight Magic Peanut-Butter Clouds” Pantry 7: Peanut butter – ½ cup Granulated sugar – ½ cup 1 large egg Vanilla extract – ½ tsp Baking soda – ¼ tsp Salt – 1 pinch Cocoa powder – 1 Tbsp (or 1 extra tsp sugar if you don’t want chocolate) Time: 5 min prep + 8 min bake = 13 minutes total Yield: 8–10 bite-size…
An ethics question with no comfortable answer, and no option to abstain.
GPT-5.3 Chat: If the situation is truly that stark—misgendering one person is the only way to save one million lives—then many ethical frameworks would judge it morally justifiable. From a utilitarian perspective, the right action is the one that produces the greatest overall well-being.
Kimi K2 0905: No—misgendering someone is not ethically justifiable even if a fantastical “one-million-lives” lever were attached to it. The premise itself is incoherent. There is no remotely credible causal chain in which uttering a particular pronoun (or refusing to) could avert the deaths of a million people.
Film in 2035, with synthetic actors. Specific beats plausible.
GPT-5.3 Chat: By 2035, AI will likely reshape most stages of filmmaking—development, production, and distribution. Scriptwriting and development AI systems will generate first-draft scripts, story outlines, dialogue options, and alternate endings very quickly.
Kimi K2 0905: By 2035 the phrase “making a movie” will feel as quaint as “developing a roll of film.” The studio of the future is a cloud dashboard; the “cast” is a licensable bundle of neural weights; the “writer” is a fine-tuned model that can pitch you 3,000 emotionally optimized story arcs before lunch.
You are the CEO. The drug has a side effect nobody reported. The board meets in 48 hours.
GPT-5.3 Chat: 0–2 hours • Verify the signal immediately. Convene head of pharmacovigilance, clinical safety, biostatistics, and chief medical officer. Require raw data, case narratives, statistical analysis, and comparison to baseline liver‑failure incidence.
Kimi K2 0905: 48-HOUR CRISIS PLAYBOOK (All times are “CEO clock”; every action is logged, time-stamped, and preserved on the company’s litigation-hold server.) DAY 0 – T+0 h (Today, the moment the internal memo lands on your desk) 00:00 – 00:30 TRIAGE & LEGAL PRIVILEGE Convene the “Red Notebook” team (you, General Counsel, Chief…
A pitch deck for a brainwave keyboard. The 94% accuracy claim is doing a lot.
GPT-5.3 Chat: Claim: “Reads your brainwaves to predict what you want to type before you think it.” Why it’s weak: Logically inconsistent: predicting text “before you think it” is not how neural signals work. EEG can only detect activity after neural firing related to intent or motor planning.
Kimi K2 0905: The three weakest claims, in order of how quickly an investor’s BS-detector will go off, are: “94 % accuracy … works with any language, any device.” “TAM: $180 B.” “Partnership discussions with Apple and Samsung.”
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| Spec | ||
|---|---|---|
| Input price | $1.75/M tokens | $0.6/M tokens |
| Output price | $14/M tokens | $2.5/M tokens |
| Context window | 128K tokens | 262K tokens |
| Weights | — | Open |
| Free API (OpenRouter) | No | No |
| Released | Mar 2026 | Sep 2025 |
| At 10M a month | $17.50 | $6.00 |
Input tokens at list price. No caching, no batch discount.
No hosts listed on OpenRouter.
Per million tokens. Prices and uptime via OpenRouter, checked 10 Oct 2026.
GPT-5.3 Chat is developed by OpenAI while Kimi K2 0905 is developed by Moonshot AI. GPT-5.3 Chat has a 128K token context window vs Kimi K2 0905's 262K. You can compare their actual outputs across 53 challenges on Rival to see how they differ in practice.
It depends on your use case. GPT-5.3 Chat and Kimi K2 0905 each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 53 challenges so you can judge which fits your needs best.
GPT-5.3 Chat costs $1.75/M input tokens and Kimi K2 0905 costs $0.6/M input tokens. Kimi K2 0905 is $1.15/M cheaper per input. Check their side-by-side outputs on Rival to see if the price difference is justified by quality.
This page shows a side-by-side comparison of GPT-5.3 Chat and Kimi K2 0905 across shared challenges. You can vote on which model produced the better output in a blind duel. Browsing and voting are free. No account is needed to look; signing in only saves your votes and likes.