Anthropic API Rate Limits & Usage Tiers Explained (2026)
TL;DR — Anthropic meters the Claude API on three axes at once: requests per minute (RPM), input tokens per minute (ITPM), and output tokens per minute (OTPM). Your ceilings are set by a usage tier (1–4) that you climb automatically as your cumulative spend grows. Hit any ceiling and you get an HTTP 429 with a retry-after header — back off and retry. A useful 2026 detail: on most models cached input tokens don't count toward ITPM, so good prompt caching effectively raises your limit.
The three limits that matter
Every Claude API key is rate-limited on three dimensions simultaneously. You hit a 429 when you cross any one of them, not all three:
| Limit | What it counts | Bites when… |
|---|---|---|
| RPM — requests/minute | Number of API calls | You fire many small requests (parallel agents, batched UI calls) |
| ITPM — input tokens/minute | Input tokens sent | You send large prompts (big repos, long histories) at high frequency |
| OTPM — output tokens/minute | Output tokens generated | You generate long outputs at high frequency |
Because the three are independent, the fix depends on which one you're hitting. A swarm of tiny requests trips RPM; a few giant-context requests trip ITPM. Read the error — Anthropic returns headers (anthropic-ratelimit-*) telling you which limit and how much remains.
Usage tiers: how the ceilings are set
Your limits aren't fixed — they scale with a usage tier, and the tier is driven by cumulative spend, not monthly spend:
| Tier | Roughly unlocked at (cumulative) | Character |
|---|---|---|
| Tier 1 | ~$5 | Entry limits — fine for prototyping, tight for production |
| Tier 2 | ~$50 | Comfortable for small apps |
| Tier 3 | ~$100 | Real production headroom |
| Tier 4 | ~$400 | Maximum self-service limits |
Beyond Tier 4, higher ceilings require a sales conversation. You advance automatically once cumulative credits cross the threshold — so if you know you'll need Tier 3 limits, front-loading credit gets you there sooner. (Exact per-tier RPM/ITPM/OTPM numbers shift over time and vary by model — always confirm yours on the official Limits page; the structure above is what's stable.)
The cache detail that effectively raises your limit
Here's the lever most people miss: on most Claude models, only uncached input tokens count toward ITPM. Cached reads are ignored by the rate limiter.
So if you run an agentic workload at an 80% cache-hit rate against a 2M ITPM ceiling, you can actually push ~10M input tokens/minute through — because 8M of them are cached reads the limiter doesn't count. Prompt caching isn't just a cost saver (cached reads bill at ~10% of normal — see Claude pay-as-you-go pricing); it's also a throughput multiplier. For how to structure prompts so they actually cache, see Claude Code token cost and context management.
Handling a 429 cleanly
A 429 is throttling, not a broken key. The right response is mechanical:
- Read
retry-after— it tells you how many seconds to wait. Honor it. - Exponential backoff with jitter — official SDKs already retry 429/5xx automatically (default 2 retries); only hand-roll if you need more.
- Check which limit you hit via the
anthropic-ratelimit-*headers, and shape your traffic accordingly — fewer/larger requests for RPM, more caching for ITPM.
For a Claude Code-specific walkthrough, see fixing Claude Code's 429 rate limit error.
Where a pooled relay changes the picture
Per-tier limits exist because you're one account talking to one endpoint. A relay sits in front of a pool of upstream capacity, which changes two things:
- No tier application to manage. You don't climb a spend ladder or file limit-increase requests — you use the relay's pooled headroom from day one.
- Failover across upstreams. When one upstream throttles, a multi-upstream relay can route around it, so a single 429 upstream doesn't stall you.
LLM API works this way: one sk- key against pooled, high-availability capacity, with both the Anthropic and OpenAI protocols on the same base URL. The honest trade is the one every relay carries — you're routing through a third party (more in what a Claude-compatible API relay is). Live rates are on the pricing page; grab a key at /register.
FAQ
What's the difference between RPM, ITPM, and OTPM? RPM caps how many requests you make per minute; ITPM caps input tokens per minute; OTPM caps output tokens per minute. You're limited by whichever you hit first — they're enforced independently.
How do Anthropic API usage tiers work? There are four tiers. Your tier is set by cumulative spend (~$5 / ~$50 / ~$100 / ~$400), and you advance automatically as credits accumulate. Higher tiers raise your RPM/ITPM/OTPM ceilings; beyond Tier 4 you contact sales.
Do cached tokens count toward my rate limit? On most Claude models, no — only uncached input tokens count toward ITPM. A high cache-hit rate effectively multiplies your usable throughput.
Why am I getting a 429 if my key is valid?
A 429 means you crossed a rate limit (RPM, ITPM, or OTPM), not that your key is bad. Read the retry-after header, back off, and check the anthropic-ratelimit-* headers to see which limit you hit.
How do I get higher Claude API rate limits? Either climb the usage tiers by spending more (cumulative), request an increase on the Limits page, or route through a pooled relay that gives you shared high-availability capacity without per-tier application.
llmapi.pro is an independent, Claude-compatible API relay; we are not affiliated with Anthropic. Claude is used for identification only. Tier thresholds and per-tier limits are summarized for reference — confirm current values on Anthropic's official Limits page.