Estimate monthly AWS Lambda costs including compute, requests, and free tier.
Last verified: April 2026
512 MB included free. Additional storage billed per GB-second.
Output will appear here...The estimator multiplies the configured memory (in GB) by average execution duration (in seconds) to get GB-seconds per invocation. It then multiplies by monthly invocation count, subtracts the free tier (400,000 GB-seconds and 1M requests), and applies the per-region price per GB-second. For provisioned concurrency, it adds a separate charge based on the provisioned GB-seconds running continuously. ARM pricing applies a ~20% discount to the compute rate.
The Lambda Cost Estimator calculates monthly AWS Lambda costs including compute charges, request fees, and free tier deductions. It accounts for memory allocation (which determines proportional vCPU), execution duration, provisioned concurrency, and Graviton (ARM) pricing. The tool helps you optimize function configuration for the best balance of performance and cost.
Your team is migrating a REST API from an EC2 t3.medium ($30/month) to Lambda. You plug in the numbers: 2M requests/month, 256MB memory, 200ms average duration. The estimator shows $6.40/month total. That's a 79% cost reduction. But you also model the spike scenario: during Black Friday your traffic hits 20M requests. At 256MB, the monthly bill jumps to $53. You increase memory to 512MB, which cuts duration to 100ms (CPU-bound), and the 20M scenario drops to $33. You've found the optimal config before writing a single line of code.
The Lambda Power Tuning tool (open source from AWS) can automatically find the optimal memory setting for your function. Many teams overpay by 40-60% because they never right-size memory after initial deployment.
Graviton (ARM) Lambda functions are ~20% cheaper per GB-second AND often run faster than x86 for most workloads. Unless you have x86-specific binary dependencies, always deploy on ARM.
If your function runs for more than 5 minutes consistently, consider whether it should be a Lambda at all. Fargate tasks or ECS services can be cheaper for long-running workloads.
Lambda charges per request ($0.20 per million) and per GB-second of compute ($0.0000166667 for x86). A GB-second is the memory allocated (in GB) multiplied by execution duration (in seconds). The free tier includes 1 million requests and 400,000 GB-seconds per month.
Not necessarily. Lambda allocates vCPU proportional to memory, so doubling memory also doubles available CPU. For CPU-bound functions, doubling memory can cut execution time in half, resulting in similar total cost but faster performance. Profile your function to find the optimal memory setting.
Provisioned concurrency keeps a specified number of Lambda execution environments initialized and ready to respond immediately, eliminating cold starts. You pay for provisioned concurrency whether functions are executing or not, at approximately 60% of the on-demand compute rate, plus the standard per-request charge.
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