Why is Claude Code using so many tokens? (and what it costs in dollars)

1. The short answer: every turn re-sends everything

Anthropic's own explanation: on each turn Claude Code sends the whole conversation so far, plus your CLAUDE.md, files it has read and your new prompt (Claude Help Center, Models, usage and limits in Claude Code). A session's token count therefore grows with context size × number of turns, not just with what you type. Prompt caching makes most of those re-reads cheap, but not free, and a cache miss bills the whole context again.

Official pages explain this, but none turns a session into dollars. This guide does, using official prices.

Much of that re-read context can be billed at cached rates; see does prompt caching save money for AI agents?

2. Where the tokens go

Fixed overhead that loads before you've typed anything. These are the components used in the worked example below.

Other sourced components to add for your own setup:

• Other MCP servers (tool search off): Notion ~17,500 (24 tools), Sentry ~6,200 (9 tools, default set), Supabase ~5,400 (29 tools), Filesystem ~2,800 (14 tools); these are o200k counts, and Claude's tokenizer counts more (mcpcost puts Claude at ~1.76x o200k at the registry median, a rough ratio). The official GitHub MCP server measured 59,084 (o200k) to 86,843 (Claude tokenizer) tokens for 47 tools (loadline). Registry median: 2,271 tokens per server (mcpcost).
• Triggered skills: Anthropic says a loaded skill is under 5K tokens (Agent Skills overview).
• Computer-use toolset ~4,500 and browser toolset ~6,600 (Anthropic pricing docs).
• CLAUDE.md, files read, tool results, thinking and output: depend entirely on your project. Check them with /context and /usage.

Measurements come from different server versions and tokenizers; see MCP tool token cost for the full table.

3. The re-read multiplier, in dollars

Anthropic's prompt cache stores the prefix in the order tools → system → messages, so tool definitions sit in the cached part. A 5-minute cache write costs 1.25x base input, a 1-hour write 2x, and a cache read 0.1x (Anthropic prompt caching docs).

Worked example (example assumptions, not a measurement): the 9,777-token fixed overhead above, a 30-turn session, each turn adding 2,000 new input tokens (your prompt, files, tool results) and 1,000 output tokens, which become context for the next turn. By the last turn the context is 96,777 tokens. "Cached" means each turn reads the previous context from cache and writes only the new part with a 5-minute TTL.

Computed from models.json. Cache-write prices are derived from the 1.25x multiplier. The last two columns divide the plan's monthly price by the cached session cost: a rough API-equivalent comparison, not a share of your plan window, because Anthropic doesn't publish window sizes in tokens (see section 6).

4. The silent burners

• Cache misses after a break. A 5-minute cache expires; the next turn re-writes the whole context at 1.25x input instead of reading it at 0.1x (that's the "one cache miss" column above). Anthropic's own advice: "Start fresh instead of resuming large sessions that have been idle ~1h" (Anthropic post on r/ClaudeCode).
• Resumed sessions. A user log on a resumed session showed "Turn 15: cache_read: 15,451 cache_creation: 42,970 ratio: 26%", i.e. most of the context was re-written, not read (r/ClaudeAI; anecdote, and the poster reported 99% after a patch).
• Subagents. Each runs its own context with its own system prompt and tools. A public Codex orchestrator run used 47K–67K uncached input and 2.2K–8.9K output per subagent; we use ~55K / ~5K as an estimate (token-usage log, single run, not Claude Code).
• Agent teams. Anthropic says agent teams use roughly 7x the tokens of a standard session (Claude Code costs docs).
• Background work. The same docs list scheduled tasks, idle goal check-ins ("at most three idle check-ins per goal"), cross-session messages that each send full context, and /compact, which reads the conversation it summarizes, while "/clear costs nothing" (costs docs).

Estimates from the sources above priced with models.json. Subagent input is priced as uncached input; real runs often get cache hits (the same Codex run cached 96% of input), which would lower this.

5. Does Claude Code use more tokens than chat?

Yes. A chat reply sends your conversation once. Claude Code also loads tool and MCP definitions, reads files, and loops: one request can mean many model calls, each re-reading the context. Anthropic's research team reports single agents use about 4x the tokens of chat and multi-agent systems about 15x (Anthropic engineering).

6. What this means for Pro and Max limits

"Both Pro and Max plans have a five-hour session limit and a weekly limit. Max plans also have a separate weekly limit for Fable. These limits are shared across Claude and Claude Code."

Source: Anthropic, Using Claude Code with your Pro or Max plan

Pro is $20/month billed monthly ($17/month annually); Max is "5x or 20x more usage than Pro" at $100 to $200/month (claude.com/pricing). Anthropic publishes no token or message numbers for these windows, so nobody can honestly say what percentage of a window a session uses. Every token above counts against them, though, and expensive patterns (Opus, cache misses, subagents) drain them faster.

User reports (anecdotes, not benchmarks; no token counts): one Max user said a 5-hour limit emptied "in ~30 mins" (X, Oct 24); a Max 20x user reported the weekly limit filling "at about half the usage it took the week before" (GitHub issue #104750). Models and settings differ, so don't compare them directly. See Claude Code usage limits for the official details.

7. Fixes, roughly in order of savings

1. /clear between unrelated tasks instead of carrying context forward; Anthropic says /clear costs nothing (costs docs).
2. Pick the model and effort per task. Opus 5.5 costs 2x Sonnet 5.5 per token in models.json, and Anthropic says "Opus burns roughly twice as fast" (r/ClaudeCode).
3. Keep tool search on (default in Claude Code; "Only tool names and server instructions load at session start", MCP docs). Measured across 10 servers: 30,357 tokens with it off vs 2,523 on (hardnumbers.dev). Per 100 turns:

   Model	Tool search off, uncached	Off, cached	On, uncached	On, cached
   Claude Opus 5.5	$12.14	$0.753	$1.01	$0.063
   Claude Sonnet 5.5	$6.07	$0.376	$0.505	$0.031

   Schema tokens only. "Cached" = one 5-minute write then 99 reads.

4. Disable MCP servers you don't use in this project.
5. Keep CLAUDE.md lean; it's re-sent every turn, and editing it invalidates the cache (Claude Code prompt caching docs).
6. Grep before reading whole files, and avoid long idle gaps mid-session.
7. Watch it: /usage recommends changes for "behaviors behind 10% or more of your recent usage" (costs docs), and /context shows what loads up front.

FAQ

8. Run your own numbers

Put your own tokens per call, calls per task and model into the calculator to get $ per task, day and month, or model your cache hit rate.

Open the TokenTab calculator Prompt caching calculator Subscription vs API

Related: MCP tool token cost · Claude Code cost per month · Claude Code usage limits.