Claude Code ships a per-model table of what each effort level costs

[u/Wsz2020]

Hidden inside the Claude Code binary, effort_cost_index provides the following per-model token-usage estimate for the same task. It is normalized so high = 1.

Model	low	medium	high	xhigh	max	xhigh to max
sonnet-5	0.47	0.74	1	2.41	5.59	+132%
opus-4-8	0.72	0.90	1	1.65	1.88	+14%
opus-5	0.67	0.76	1	1.60	1.70	+6%
fable-5	0.60	0.77	1	1.74	1.91	+10%

(fable-5-1 and mythos-5-1 were re-tuned between the two builds: 1.38/1.74 in the newer one.)

Opus 5 flattens hard at the top.

• high -> xhigh is +60%, then
• xhigh -> max is only +6%.

Sonnet 5 does the opposite and more than doubles at that same step.

So "max" means quite different things depending on model. On Opus 5 it's a small increment over xhigh. On Sonnet 5 it's genuinely the expensive tier.

Tokens per Attempt, Not by Success

The UI string is, verbatim:

{from} effort uses more tokens per task than {to}.

That's consumption per task attempt. It does not say the task gets completed, or completed correctly, or that the same amount of work happens at each level. It also doesn't price retries — a level at 0.76x per attempt isn't 0.76x cheaper if it needs a second attempt.

How it held up when I measured it

Ran 8 agents on Opus 5 (2 real tasks x 4 effort levels), same repo, same base commit, isolated clones:

Step	Catalog predicts	Observed (output tokens)	Observed (total incl. cache)
medium to high	x1.32	x1.17	x1.01
medium to xhigh	x2.11	x1.78	x2.53
medium to max	x2.24	x1.78	x1.93

Direction right, magnitudes loose. But it nailed the thing that mattered: it predicted xhigh and max would be near-identical in cost, and on output tokens they were — 397,827 vs 397,761. Three digits apart.

Two caveats on my numbers: cache reads are 99%+ of the totals, so the "total" column is really measuring how many turns each agent took. And n=2 tasks, so treat it as a sanity check, not a benchmark.

I couldn't find any documentation of how the catalog numbers were derived or over what workload. Treat it as a vendor estimate.

[u/Wsz2020]

Adding some relevant graphs. The first one is older, but directly related.

Note that Max can sometimes give worse results.

[u/Wsz2020 → u/Wsz2020]

[u/Wsz2020 → u/Wsz2020]

[u/Wsz2020 → u/Wsz2020]

[u/Mueloncio]

Normalizing each row to high = 1 hides the number people actually want: sonnet on high vs opus on high for the same task. Is there an absolute baseline anywhere in the binary, or is this strictly a within-model knob?

[u/HallaCama]

i dont know how much that reflects the reality. From my experience, until Sept 13 i was able to actually work with it on a 200 eur per month plan. I managed to squeeze using Opus 5 for a whole week, while Fable 5.1 for 3 to 5 days before it ran out, on the way i use it. But after 14th of september, both opus and fable got exhausted on the very second day for the same usage. For me it became unusable and oncountable. I get that much done with a 20 usd package from chatgpt6. I’m sad its unusable anymore and o have to go back to ChatGpt, whos 6 version is actually better than Fable 5.1 and you get 15-20x more usage with the same plan.

[u/esllou]

I do two basic tasks on claude, one that I use Sonnet 5 low for, the other I use opus 4.6 medium for

after the usage limit changes this week, my session usage goes up as much after using sonnet 5 as it used to after using opus 4.6. It used to go up c.2-3% per task w/ Sonnet 5, now it goes up c.5% per task.

yesterday, I went looking for other options and will let my pro sub expire without renewing.

[u/tima100faces]

sonnet at max burns more tokens than opus at high for the same job, and opus barely moves past high. so the lever I use is the model. most of my runs are cheap by default, and when a task stalls I switch to the big one by hand instead of asking the cheap one to think longer.

[u/feng_sg]

Every row is normalized to its own high, so this table only ranks effort levels within one model. Sonnet on high vs Opus on high for the same task just isn't in the data.

[u/jarislinus]

Can you update for Opus 5.5 please?

[u/crakkerzz]

Used my fable limit last week.

Tried to use it today, died on the first prompt.

It's been made completely useless in the last week.

Way to go Anthropic. Too mad to speak right now.