Step-by-Step Fix
1. Understand Your Two Cost Sources
Before estimating costs, recognize that OpenClaw automation has two separate billing components:
OpenClaw platform fee: A fixed monthly subscription charged by OpenClaw. This covers the infrastructure, scheduling engine, tool execution environment, and dashboard access. The cost is predictable and does not vary with usage volume within your plan's limits.
Anthropic API fee: A variable cost based on the number of tokens consumed by your Claude API calls. This is charged by Anthropic directly and can vary significantly based on how often your agents run, which model you use, and how much text they process.
Understanding this distinction prevents confusion when you receive two separate charges.
2. Estimate Per-Run Token Costs
Calculate your expected token usage per agent run:
- Input tokens: The system prompt + conversation history + tool call results passed to Claude on each turn
- Output tokens: The text Claude generates in response
As a reference:
- Claude Haiku: ~$0.25 per million input tokens, ~$1.25 per million output tokens
- Claude Sonnet: ~$3 per million input tokens, ~$15 per million output tokens
- Claude Opus: ~$15 per million input tokens, ~$75 per million output tokens
A typical agent run processing a 1,000-word web page (approximately 1,500 tokens) and generating a 200-word summary (approximately 300 tokens) costs roughly:
- Haiku: $0.00075 per run
- Sonnet: $0.009 per run
- Opus: $0.045 per run
3. Calculate Monthly Estimates
Multiply your per-run cost by your expected run frequency:
Monthly cost = (cost per run) × (runs per day) × 30
Example: A cron job running every hour (24 times/day) using Claude Sonnet to process a medium-length page:
$0.009 × 24 × 30 = $6.48/month in Anthropic API costs
Add your OpenClaw subscription fee to get your total monthly automation cost.
4. Set a Hard Spending Limit in Anthropic Console
- Go to console.anthropic.com
- Navigate to Billing > Usage Limits
- Set a Monthly Spend Limit — start with 2x your estimated monthly cost as a safety buffer
- Enable Email Alerts at 75% of the limit
When the limit is reached, Anthropic blocks further API calls. Your OpenClaw agents will fail with an error message rather than continuing to charge you. This is the most effective safeguard against runaway costs.
5. Monitor Usage Weekly for the First Month
In the Anthropic console, check Usage weekly for the first 4 weeks of a new automation:
- Total tokens per day — watch for unexpected spikes
- Tokens per model — confirm your agent is using the intended model
- Call count — verify your cron schedule is triggering at the expected frequency
In OpenClaw, check Run History to confirm jobs are completing successfully and not entering retry loops.
6. Optimize for Cost Efficiency
After measuring actual usage, apply these optimizations:
- Switch to Haiku for simple tasks: Text extraction, classification, and formatting tasks rarely require Sonnet or Opus
- Cache repeated context: If your agent always starts with the same system prompt, keep it short — each character of system prompt is charged as input tokens on every run
- Truncate large inputs: If your agent scrapes web pages, limit input to the most relevant section rather than passing the entire page HTML
Why This Happens
Anthropic API costs are usage-based and can compound quickly when automation runs at high frequency. Unlike most SaaS tools with fixed pricing, the token-based model means costs scale directly with the volume and verbosity of your agent's conversations. A bug that causes an agent to retry indefinitely can generate thousands of API calls in minutes. Without a hard spending limit, there is no automatic stop — the charges accumulate until you notice and intervene manually.
Common Mistakes to Avoid
- Not setting an Anthropic spending limit: This is the single most important step for preventing unexpected charges. Do it before running any high-frequency automation.
- Using Opus for all tasks by default: Opus is approximately 60 times more expensive than Haiku. Use the cheapest model that produces acceptable quality for each specific task.
- Not accounting for tool call responses in token count: When your agent uses tools (browser, bash, file system), the tool response is returned as input tokens in the next API call. A browser tool that returns a large web page can add thousands of unexpected input tokens per run.
- Estimating based on text length alone: Token counts are not identical to word counts. Code, URLs, and special characters consume more tokens per character than plain English prose. Use Anthropic's tokenizer tool for accurate estimates.
FAQ
Q: Is there a way to see a per-run cost breakdown in OpenClaw?
OpenClaw's run history shows the token counts for each run if you open the run detail view. Multiply the input and output token counts by the per-token rate for your model to calculate the Anthropic API cost for that specific run. For a more automated view, use Anthropic's usage dashboard at console.anthropic.com — it shows daily token usage by model, which you can correlate with your OpenClaw run schedule to identify expensive runs.
Q: What happens to my OpenClaw agents if I hit the Anthropic spending limit?
When your Anthropic API spending limit is reached, Anthropic returns a billing error on all subsequent API calls. Your OpenClaw agents will fail with an error message indicating the API key is over its limit. The agents themselves are not disabled — they will attempt to run on schedule but fail at the API call step until the new billing month begins or you raise the limit. Set up failure notifications in OpenClaw so you are alerted immediately when this happens rather than discovering it hours later.
Q: Can I use prompt caching to reduce Anthropic API costs in OpenClaw?
Yes, if your agent uses a consistent, long system prompt that repeats across runs. Anthropic supports prompt caching for inputs over 1,024 tokens, which reduces the cost of repeated context by approximately 90% for cached portions. In practice, if your OpenClaw agent starts every run with the same 2,000-token system prompt, enabling prompt caching reduces the effective input token cost of that prompt to near zero after the first run. Check Anthropic's documentation for how to enable caching via the API parameters in your OpenClaw workflow configuration.
Q: My OpenClaw costs doubled this month with no obvious change. How do I investigate?
Check three things in order: (1) Anthropic console → Usage → compare token counts by day this month versus last month to identify when the spike started. (2) OpenClaw run history → look for runs that took unusually long or ran more frequently than expected around the same date. (3) Your workflow configuration → check if any model was changed to a more expensive tier or if any new tool calls were added that return large responses. The most common culprit is an agent entering a retry loop or a cron schedule that was accidentally changed from hourly to per-minute.
Q: Does OpenClaw charge based on successful runs only, or also failed runs?
OpenClaw's platform fee is subscription-based and does not charge per run. Anthropic API costs, however, are charged for every API call that reaches Anthropic's servers — including calls that result in errors. If your agent makes a Claude API call and the response is a rate limit error or a tool execution failure, you are still charged for the tokens in the request. This means failed runs in a retry loop are just as expensive as successful ones from an Anthropic billing perspective.
Related Issues
- OpenClaw rate limits affecting runs
- OpenClaw billing – charged but plan not updated
- OpenClaw subscription not activating after payment
- OpenClaw model access errors – plan does not allow model
Additional FAQ
Q: Why do I see a pending charge that later disappears? A disappearing pending charge is an authorization hold — a temporary reservation placed by your bank to verify funds are available. When a payment fails or is canceled, the hold is released without any actual charge being made. Most banks release authorization holds within 3–7 business days. If you see a hold older than 7 days, contact your bank and ask them to release it manually, referencing the merchant name and transaction date.
Related Articles
- OpenClaw login / API key fix
- OpenClaw rate limits affecting runs
- OpenClaw agent not starting
- OpenClaw tool calls failing