AI Cost Watch
Dated cost notes, model guides, and worked examples — with the assumptions and arithmetic on the page.
The Playbook
The Cost Engineering Playbook
Every copy-and-adapt pattern behind a low AI bill — routing, caching, the effort dial, compiling the repeats. Given away →
Reference
Know Your Models
The seven axes that actually separate AI models — tier, price, token efficiency, speed, context, and what each is good at. Plain terms →
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Cautionary tales and cost wins — when there's something real to say. No spam.
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Featured — Oct 14, 2026
The model price is only the first line of the bill.
Three transparent worked costs: a subscription, an API workload, and an agent run. The assumptions, the arithmetic, and the costs a model price leaves out. No new quality benchmarks.
Read the full piece →Sep 2026
Where System One models win — and where they don't
A new class of model returns a label or a probability, never text — and it's decided the live card on this page. Describe a task, watch it pick a class, and see the receipt: time, tokens, and cost.
Read the full piece →Sep 2026
The Open Model Map — where open models actually win
AT&T pushes ~45B tokens/day and holds costs flat by routing 25–40% through open models. The honest translation for teams 1/10,000th the size: three dials, a dated use-case fit table, and where open still loses.
Read the full piece →Jun 2026
Tokenmaxxing & the Cache Trap — when 'switch models to save' backfires
Only 8–16% of tasks need a premium model, yet teams pick premium 85% of the time. But naive model-switching in long sessions can cost 4.9× MORE — the honest version, building on AT&T's TM Forum MoDaaS research.
Read the full piece →The Surprise Ledger · No. 3
The test suite said READY. Three of five recommendations didn't exist.
One unexpected finding a week, from real work — with the evidence, so you can check it. Read this week’s →
The Watch
What’s happening to AI costs — curated, sourced, and cut down to what matters.
Oct 14, 2026
The model price is only the first line of the bill.
Source: Scruuge Cost Watch · provider documentation and illustrative arithmetic
Scruuge’s TLDR
Test the cheaper candidate, check your cache hits, and consider batching before changing a model that already works. Three dated calculations show the assumptions. No models were run for this edition.
Sep 2026
Volume up 5×, cost flat — AT&T's open-model tokenomics
Scruuge’s TLDR
This is the same AT&T team whose research underpins our cache-trap breakdown — now saying the quiet part at Fortune-50 scale: routing is the discipline, open models are where the easy majority of tokens go, and the hard minority stays on frontier models on purpose. The 90% headline hides the router and the fine-tuning it took; our Open Model Map translates which of those moves survive at small-firm volume.
Aug 2026
Bake-off № 1 — a $0.005 model matched a $0.36 model
Source: Scruuge bake-off · one task, four models, verbatim answers
Scruuge’s TLDR
Cheap didn't mean bad and pricier didn't mean safe — the cheapest model was excellent and the second-cheapest was the one that would have hurt you. Fit for the task is the axis, not price in either direction. That's why we run the real task instead of quoting a leaderboard.
Aug 2026
Nobody upgraded — the newest frontier model won 3.5% of spend
Source: Ramp AI Index (~70,000 companies' card spend) · Financial Times, 23 Aug 2026
Scruuge’s TLDR
The best model available and the model people actually pay for are two different things. Your peers already voted, with their credit cards, for good-enough-and-cheaper. You're not behind for staying put — you're behind if you never made the choice deliberately.
Aug 2026
You can no longer wait for the next model to fix your costs
Source: Drew Breunig (via Simon Willison)
Scruuge’s TLDR
Deferring optimization used to be rational — the next release arrived cheaper and papered over your problems. That curve flattened. The work you were sensibly putting off (routing, context discipline, compiling repeats) just became the work.
Aug 2026
Enterprise AI usage grew 7× in 9 months — and half of it is documentation
Scruuge’s TLDR
The first hard measurement of what enterprises actually do with AI: usage grew 7× in nine months, and the biggest single category is documentation and technical writing. The paper never mentions cost — but that combination is the whole ballgame. Your highest-volume workload is also your most routable, and it's almost certainly running on whatever the default model is.
Jul 2026
You didn't type 3.77 billion tokens — 96% was reused input
Source: Nate B. Jones — '15 rules' to stop token piling (token-saver skill, Ringer)
Scruuge’s TLDR
Every message re-sends the entire conversation — that's how LLMs fake memory — so your 10th message pays for the 9 before it, and every retry multiplies it. The fix isn't a bigger context window; it's keeping your desk clean: start fresh when the job changes, carry the artifact not the argument, and store answers you can look up.
Jul 2026
Open source isn't automatically cheaper — Kimi K3 breaks the assumption
Source: Moonshot Kimi K3 (open weights, late Jul) · a widely-shared analysis
Scruuge’s TLDR
Open-weights ≠ automatically cheaper. Judge a model by the finished bill, not the per-token rate: a verbose 'budget' model on a big footprint can beat a pricier frontier one. Pick open source for control, fine-tuning, and resilience — not a blanket cost win. Don't generalize DeepSeek's one serving win into a law.
Jul 2026
88% deployed AI; only 39% can prove it paid off
Source: Cursor — 'CFOs and the New Economics of AI' (Jordan Topoleski)
Scruuge’s TLDR
You will not optimize your way to a flat AI bill — cheaper tokens get spent on more (Jevons). Spend isn't the enemy; unmeasured spend is. Cut the waste (floor), steer the rest toward where it compounds into revenue (ceiling), and measure per-outcome, not per-token.
Jul 2026
DeepSeek made intelligence ~7× cheaper to serve — and published the recipe
Source: DeepSeek DSpark paper (MIT-licensed) · Deutsche Bank cost estimate
Scruuge’s TLDR
The race stopped being 'who's smartest' and became intelligence per dollar, per second, per watt. A chip-starved lab just lapped the field on that scoreboard and gave away the blueprints — so the 'best model' you picked last quarter is probably not the one you should pay for now.
Jul 2026
Cheap execution is the floor, not the strategy
Source: Cost Engineering · on where AI value moves (Hashimoto's $40 test, Stripe)
Scruuge’s TLDR
Cutting your bill is the floor — necessary, and soon table stakes for every competitor. The ceiling is where you point the frontier: the questions no one else thought to ask. We'll cut the floor honestly, then tell you when cost was never your real constraint.
Jul 2026
Model routing — plan with the best, execute with the cheap
Source: Cost Engineering · a widely-shared model-routing walkthrough (recomputed)
Scruuge’s TLDR
Best model to plan, good-enough model to execute. You're not buying a smarter AI for the whole job — you're buying judgment for the 10% that needs it and paying wholesale for the 90% that doesn't. Route by task, never mid-session.
Jul 2026
Compiled AI — stop paying to re-reason the same thing
Source: INXM (the '#compiledAI' post)
Scruuge’s TLDR
The token bill is a symptom; the disease is re-reasoning. Use AI to figure a repeating task out ONCE, compile the answer into deterministic automation, then run that — not the model — every time after.
Jun 2026
Companies are blowing their entire annual AI budget in months
Source: Financial Times (via Yahoo Finance)
Scruuge’s TLDR
You can't cut what you can't see — and roughly three in four teams can't. Uber isn't an outlier; it's what usage-based pricing does without a meter. Scruuge is the two-minute meter you run before finance finds out.
Jun 2026
Anthropic quietly doubled its own Claude Code cost estimate
Source: Anthropic docs (updated Apr 15) · flagged by Ed Zitron; reported by Fortune/AOL
Scruuge’s TLDR
When the vendor quietly doubles its OWN cost estimate, that's not a rounding error — it's the trajectory. The meter only spins faster from here. Map your waste before the next 'quiet update.'
Jun 2026
Cache-aware routing cuts LLM cost 50–90% (TM Forum MoDaaS)
Source: AT&T CDO · TM Forum MoDaaS (TM Forum Copenhagen 2026)
Scruuge’s TLDR
Hard proof the waste is real — and a warning we took to heart: switching models to save can backfire in long sessions. Switch your default, not your session.
Aug 2026
125 billion parameters, 6 billion doing the work
Source: Qwen3.8-Flash-Next (via Simon Willison)
Scruuge’s TLDR
Headline parameter counts are marketing; active parameters are the bill. A 'huge' MoE model can be cheap to run and a 'small' dense one expensive — always ask what actually fires per request.
Jun 2026
GitHub Copilot moves to usage-based billing
Source: GitHub
Scruuge’s TLDR
Flat-rate AI is ending. Usage-based billing means your bill now scales with every token your team burns — including the 40–60% that's pure waste. The teams that mapped that waste first will feel this least.
Jun 2026
Nvidia VP: 'the cost of compute is far beyond the costs of the employees'
Source: Axios / Fortune (Bryan Catanzaro, VP applied deep learning, Nvidia)
Scruuge’s TLDR
When a chip-maker's own VP says compute costs more than the humans, the 'AI is basically free' era is over. Budget for it like the real line item it's become — then trim it.
Jun 2026
MIT: 95% of enterprise AI pilots deliver no measurable financial return
Source: MIT NANDA initiative (as reported)
Scruuge’s TLDR
The uncomfortable half of the story: a lot of AI spend isn't paying for itself. Scruuge's honest line — the problem is usually the WASTE, not the tool. Cut the tokenmaxxing before you conclude AI doesn't work.