Cloudflare Worker CPU Time Budget Calculator

Cloudflare Workers on the free plan have a 10ms CPU time limit per request. The paid Workers Paid plan raises this to 50ms CPU time (30s wall clock time) on the Bundled pricing, or up to 30 seconds CPU time on Unbound pricing. CPU time measures active computation, not waiting for I/O like fetch() calls.

CPU time counts only the time your Worker's JavaScript is actively running. Wall clock time includes waiting for external fetch() calls, KV reads, and other I/O. A Worker can take 30 seconds of wall clock time but only 50ms of CPU time. Most Workers that do I/O spend very little CPU time relative to wall clock time.

Workers that exceed their CPU time limit receive a 1101 error (Worker threw exception). Your Worker is terminated mid-execution. This cannot be caught with try/catch inside the Worker. You need to either optimize your code, upgrade to Unbound pricing, or offload heavy computation to Durable Objects or other services.

Use Date.now() or performance.now() to measure elapsed time. Within a Worker, you can implement a budget tracker that periodically checks elapsed CPU time and either completes early or returns a partial result. The Cloudflare dashboard also shows P50/P99 CPU time metrics for your deployed Workers.

Use Bundled ($5/month flat, 10M req/month) when requests are short and CPU time stays under 50ms. Use Unbound (billed per CPU-ms) for compute-intensive tasks like image processing, data transformation, or AI inference that need more than 50ms CPU time. Unbound is also better for unpredictable workloads.