Fable 5 vs Opus vs Sonnet: which Claude for which job now.
"Use the most powerful model" is bad advice. The most powerful model is slower, costs more, and is overkill for most of what you do all day. Here's a clear way to pick the right Claude for the task in front of you — and a plan for the June 23 pricing change.
The mental model
Match the model to the task's difficulty, not your ambition.
Think of it like vehicles. You don't take a freight truck to pick up milk, and you don't move a houseful of furniture in a hatchback. Fable 5 is the freight truck: unmatched on long, heavy, complex hauls — and wasteful for a quick errand. Sonnet is the everyday car: fast, cheap, perfectly good for the trips you take most. Opus 4.8 sits in between, and notably, it's what Fable quietly falls back to on sensitive topics.
01 The three Claudes at a glance
| Model | Best at | Reach for it when… |
|---|---|---|
| Fable 5 | Long, complex, multi-step work; vision; tasks that run for a while on their own | The job would take you hours and has many moving parts — a full analysis, a big migration, a research project, reading detailed figures |
| Opus 4.8 | Strong general reasoning and writing, a step below Mythos-class | You want high quality but the task is bounded — a serious document, a tricky problem, careful reasoning that doesn't need hours of autonomy |
| Sonnet | Speed and value on everyday tasks | Most of your day: drafting emails, summarizing, quick questions, routine writing. Fast and inexpensive, and good enough that you won't miss the extra power |
02 The 3-question decision
Before you pick, ask yourself three things:
- How long would this take me by hand? Minutes → Sonnet. An afternoon or more → Fable 5. In between → Opus.
- How many steps does it involve? One ask, one answer → Sonnet. A chain of dependent steps where each builds on the last → Fable 5.
- Does it involve images, charts, or documents I need read precisely? If yes, lean Fable 5 — vision is where its lead is largest right now.
Two or three answers pointing at "big" means Fable 5 earns its keep. Otherwise, save it — you'll get a faster answer and spend less.
03 Worked examples
Knowledge work
- "Summarize this email thread and draft a reply" → Sonnet. Bounded, quick, routine.
- "Read these 12 reports and build me a board memo with the cross-cutting themes" → Fable 5. Long, multi-source, synthesis-heavy.
- "Pull every number from this scanned financial statement into a clean table" → Fable 5. Vision-precise extraction is its strength.
- "Rewrite this proposal to sound more confident" → Opus or Sonnet. Quality matters, but it's one focused pass.
Start most tasks on Sonnet. If the answer feels thin, or the task turns out to have more moving parts than expected, then escalate to Fable 5. Escalating up is cheap; you rarely need to start at the top.
04 The money: pricing and the June 23 change
Two pricing realities to plan around.
On the API, Fable 5 and Mythos 5 cost $10 per million input tokens and $50 per million output tokens — less than half what the earlier Mythos Preview cost. For developers, that's a meaningful price drop for top-tier capability.
On subscriptions, the window matters. Through June 22, Fable 5 is included free on Pro, Max, Team, and seat-based Enterprise plans. On June 23, Anthropic removes it from those plans — after that, using it requires usage credits, though Anthropic says it intends to restore Fable to subscriptions once capacity allows.
How to spend credits wisely after June 23
- Default to Sonnet for the everyday. It stays included; it covers most of your day; it doesn't touch your credits.
- Save Fable 5 for the tasks that justify it — the ones from the 3-question test where the answer is clearly "big." That's where the credits pay for themselves in time saved.
- Don't auto-select the top model. A credit spent on a task Sonnet could've done is a credit you don't have for the migration that actually needed Fable.
Final challenge: sort your week
List the five Claude tasks you did this week. Tag each one Sonnet, Opus, or Fable 5 using the 3-question test. You'll likely find four are everyday Sonnet jobs and one is the real heavyweight. That ratio — mostly fast and cheap, occasionally powerful — is how to use the lineup well and keep your credits for what matters.
What you can do now
- Match a task to the right Claude by difficulty, not by ambition
- Use the 3-question test (length, steps, vision) to choose quickly
- Default to Sonnet and escalate to Fable 5 only when the task is genuinely big
- Understand the API pricing and the June 23 subscription change
- Spend usage credits on the tasks that actually justify a Mythos-class model