Model comparisons - tested October 2026 by Malte Pruser. How we test.
Verdict
Claude Fable 5.1 took 6 of 10 tasks, Perplexity Sonar Pro took 1 and 3 were too close to call. Perplexity's only clear win was the product email, where the shorter, more faithful answer beat Claude's invented rollout details. Everywhere else Claude won by showing more working - the special-character mapping that Sonar's own slugify test missed, the jug-state table, the correctly rounded 1,713 customers. Sonar Pro is much cheaper per answer and cites sources inline, but the citation markers did not turn into better facts. Pick Claude Fable 5.1 for depth and correctness; pick Perplexity Sonar Pro when the short, sourced answer is enough.
Verdict by task
| Task | Winner | Why |
|---|
| Writing | Split | One each. Sonar Pro stayed more faithful to the brief on the product email while Claude invented detail; Claude wrote the better 12 year old explanation and kept the stronger "far more" claim. |
| Coding | Claude Fable 5.1 | Sonar's slugify failed its own œuf test; Claude maps non-decomposing letters explicitly. On the rounding bug neither fully fixed it, but Claude was the better starting point. |
| Research | Split | Same thresholds and same Directive on the EU VAT scheme; same ranking on populations. Sonar reads quicker, Claude adds the legal context. |
| Data analysis | Claude Fable 5.1 | Both got the numbers right, but Claude covered growth as well as revenue and correctly rounded the projection to 1,713 where Sonar got 1,712. |
| Reasoning | Claude Fable 5.1 | Both solved both puzzles. Claude won the water jug by spelling out jug states; the dinner split was a clean split. |
Results, prompt by prompt
writing - winner: Perplexity Sonar Pro
Prompt: Write a 120 word product update email to existing customers of a small accounting software company announcing that bank feeds now sync every hour instead of once a day. Plain, friendly, no exclamation marks, end with one clear call to action.
- Perplexity Sonar Pro - partial, no hallucinations, 1s. Short of the 120 word target but stayed faithful to the supplied facts: plain, friendly, ends on one CTA.
- Claude Fable 5.1 - partial, 1 hallucination, 2s. Readable and warm, but invents customer requests and rollout details that were not in the brief, steers the ending toward connecting an account, and does not close on the requested CTA.
writing - winner: Claude Fable 5.1
Prompt: Rewrite this paragraph so a 12 year old understands it, keep every fact, max 80 words: 'Compound interest is interest calculated on the initial principal and also on the accumulated interest of previous periods. Because the base grows each period, the growth is exponential rather than linear, which is why long time horizons matter far more than the interest rate alone.'
- Perplexity Sonar Pro - partial, no hallucinations, 3.6s. Age-appropriate and keeps every fact, but softens "matter far more" to "can matter more", weakening the original claim.
- Claude Fable 5.1 - pass, no hallucinations, 1.8s. Clear 12 year old friendly rewrite with the snowball image; preserves every fact including the stronger "far more" claim.
coding - winner: Claude Fable 5.1
Prompt: Write a Python function slugify(title: str) -> str that lowercases, replaces spaces and punctuation with single hyphens, strips accents (é -> e, ß -> ss), and returns an ASCII-only slug. Include tests for "Crème Brûlée à L'œuf" and "Hello, World!".
- Perplexity Sonar Pro - fail, 1 hallucination, 2.2s. Handles ß explicitly but fails its own œuf test, producing creme-brulee-a-l-uf instead of creme-brulee-a-l-oeuf because non-decomposing letters get dropped.
- Claude Fable 5.1 - pass, no hallucinations, 1.5s. Explicit mapping table for ß, æ, œ and ø plus the decomposition fallback; passes its own œuf and façade cases.
coding - winner: Split
Prompt: This JavaScript has a bug: users report the total is sometimes off by one cent. Find it and fix it. function total(items) { let t = 0; for (const i of items) { t += i.price * i.qty; } t += t * 0.2; return Math.round(t * 100) / 100; }
- Perplexity Sonar Pro - partial, no hallucinations, 2.2s. Identifies binary floating-point as the bug and suggests integer cents, but still computes tax in floats and assumes a line-by-line rounding policy it never establishes.
- Claude Fable 5.1 - partial, no hallucinations, 1.9s. Explains the cent accumulation clearly and is the better starting point for prices already in whole cents, but likewise keeps float tax math and overstates the fix.
research - winner: Split
Prompt: What is the current EU VAT registration threshold for small businesses selling online across EU countries in 2025? Give the figure and the rule it comes from.
- Perplexity Sonar Pro - pass, no hallucinations, 4.2s. Correctly separates the EUR 100,000 cross-border cap from the EUR 85,000 maximum domestic exemption and names Directive (EU) 2020/285; concise and easy to read.
- Claude Fable 5.1 - pass, no hallucinations, 4.3s. Same two thresholds and same Directive, with more legal context on how the exemption travels between Member States.
research - winner: Split
Prompt: List the 5 largest countries by population in 2024 with their approximate population and a source you would cite.
- Perplexity Sonar Pro - pass, no hallucinations, 1.2s. Correct UN ranking with more precise figures and a source column for each country.
- Claude Fable 5.1 - pass, no hallucinations, 2.9s. Same ranking and consistent figures, explicitly labels mid-year estimates and presents the UN source cleanly.
data - winner: Claude Fable 5.1
Prompt: Here are monthly revenue figures in EUR for a shop: Jan 41200, Feb 38900, Mar 45100, Apr 42800, May 47600, Jun 51200. Compute month-over-month growth, identify the best and worst month, and tell me the average monthly growth rate.
- Perplexity Sonar Pro - pass, no hallucinations, 3.8s. Correct month-over-month table, but only reads best and worst on revenue and skips the growth-rate interpretation and the lowest-revenue call.
- Claude Fable 5.1 - pass, no hallucinations, 0.9s. Covers both readings of best and worst - revenue and growth - and flags the lowest-revenue month. Minor terminology slip: calls monthly compound growth CAGR instead of CMGR.
data - winner: Claude Fable 5.1
Prompt: A SaaS company has 1,240 customers paying an average of 49 EUR per month. Monthly churn is 3.1% and they add 85 new customers each month. Project the customer count and MRR after 12 months.
- Perplexity Sonar Pro - partial, 1 hallucination, 4.1s. Right recurrence setup, but rounds the projected customer count to 1,712 where the correct rounding is 1,713.
- Claude Fable 5.1 - pass, no hallucinations, 3.2s. Correct 1,713 projection with a full month-by-month table; bases MRR on the rounded count, which deserves a caveat but keeps the answer usable.
reasoning - winner: Claude Fable 5.1
Prompt: I have a 3 litre jug and a 5 litre jug and unlimited water. Give the shortest sequence of steps to end with exactly 4 litres in the 5 litre jug.
- Perplexity Sonar Pro - pass, no hallucinations, 2s. Correct six-step solution but pads the end with an unneeded follow-up offer.
- Claude Fable 5.1 - pass, no hallucinations, 2.1s. Same six steps with explicit jug states after each action - the easiest answer to verify.
reasoning - winner: Split
Prompt: Three colleagues need to split a 187 EUR dinner. Anna had no drinks and only ate a 41 EUR main. Ben and Clara shared a 58 EUR bottle of wine equally and each ate a 44 EUR main. Who owes what?
- Perplexity Sonar Pro - pass, no hallucinations, 2.3s. Correct EUR 41 / 73 / 73 split assuming Ben and Clara share the wine equally, with a sum check.
- Claude Fable 5.1 - pass, no hallucinations, 3.6s. Same split and check, plus a second consistency check on the food total.
Frequently asked questions
Which is better, Perplexity or Claude?
Claude Fable 5.1 took 6 of 10 tested tasks, Perplexity Sonar Pro took 1 and 3 were split. Claude wins on depth and correctness; Perplexity wins when the short, sourced answer is enough and it cost about 14x less per answer in this round.
Which is cheaper, Perplexity or Claude?
Perplexity Sonar Pro by a wide margin: roughly $0.03 across the ten prompts versus roughly $0.44 for Claude Fable 5.1, measured on the API, because Claude writes far longer answers. Both averaged about 2.5 seconds per answer.
Is Perplexity or Claude better for coding?
Claude. Sonar's slugify failed its own œuf test because it drops letters that do not decompose, while Claude maps them explicitly. On the cent-rounding bug neither fully fixed the accounting policy, but Claude was the better starting point.
Can I use Perplexity and Claude in the same place?
Yes. Krater gives you Perplexity Sonar Pro, Claude Fable 5.1 and 500+ other models in one workspace, and the Model Arena sends one prompt to several models side by side, which is how this comparison was run.
How was this comparison tested?
Both models received the same ten prompts with default settings and no system prompt on 14 October 2026, the same set used across our tested head-to-heads. We recorded time to a complete answer and the real model cost per answer, fact checked every claim, scored completion as pass, partial or fail, and then ranked the answers blind. The full procedure is on our methodology page.
Will this comparison be updated?
Yes. Flagship comparisons are rerun monthly and whenever a provider ships a new version. The tested month and model versions are shown at the top of the page.
