How to stay ahead of AWS Lambda costs 

By Eyal Katz May 15, 2024

Severless is excellent, right? Faster development and less infrastructure hassle – but those AWS Lambda costs can sneak up on you.

Over 70% of AWS customers are using serverless now.

Seems like everyone’s jumping on the serverless bandwagon – and for good reason. It speeds up development and cuts down on the nitty-gritty infrastructure stuff. All this is a developer’s dream in a lot of ways. 

Before diving into all the advantages of AWS Lambda (and those bills start to stack up), let’s break down how it works and how those costs add up. That way, we can figure out the best ways to keep things under control.

What is AWS Lambda, and how does it work? 

AWS Lambda is a serverless computing service from Amazon. Instead of managing your servers, Lambda lets you run code responding to events like file uploads, API requests, and database changes. Lambda handles the servers, scaling, and maintenance entirely behind the scenes.

Key Benefits for Developers

  • Rapid Development & Deployment: Integrate with 200+ AWS services to quickly spin up features and services.
  • Zero Server Management: Focus on your code – Amazon handles the infrastructure.
  • Pay-As-You-Go: Only pay for actual execution time, ideal for specific workloads.
  • Robust Security: Lambda integrates with security tools to detect misconfigurations, exposed secrets, and other vulnerabilities.

How Lambda Supports Strong Security Practices

AWS Lambda’s flexibility and integration capabilities make it an excellent fit for enhancing your security posture. You can build more robust and secure applications by strategically integrating security measures into your serverless code and its surrounding ecosystem. 

Here’s how Lambda specifically supports critical security practices:

  • CI/CD integration
  • Shift-left security
  • Secrets protection
  • Public blindspot monitoring

Integrating security into your Lambda functions offers a significant advantage. CI/CD integration automatically scans your code with every update, preventing vulnerabilities. Shift-left security empowers you to address issues early, saving you from future headaches.

Furthermore, Lambda helps you safeguard your most sensitive assets.  Secrets protection actively scans your code and configurations to help prevent leaks of critical API keys, credentials, and other data that attackers could exploit. Public blindspot monitoring extends your vigilance beyond your codebase, helping you identify exposed resources and vulnerabilities in external repositories or cloud services that could put your applications at risk.

How much does AWS Lambda cost?

AWS Lambda’s pricing is usage-based, meaning you only pay for the time your code runs.  Here’s the breakdown:

  • Executions: How many times is your function triggered?
  • Duration: How long does your code run each time (rounded to the nearest millisecond)?
  • Memory Usage: How much memory is your function allocated?

These factors are combined to calculate your costs, which vary slightly based on region and architecture.

Example: Currently, on the US East Coast, it costs $0.0000166667 for every GB-second of compute time for an x86-based function, plus $0.20 per million requests.

You can control the memory allocation for your function. Optimizing this is key. If you allocate too much memory or your code is inefficient, you could end up paying significantly more than necessary.

AWSLambda Costs

Don’t Let Misconfigurations Drain Your Wallet

Overlooked security flaws in your AWS Lambda setup can lead to unexpectedly high costs, going beyond the immediate risks of a security breach.

How Misconfigurations Drive Up Lambda Costs:

  • Unauthorized Resource Usage: Attackers can exploit vulnerabilities to hijack your Lambda functions, resulting in skyrocketing usage charges.
  • Data Exfiltration Costs: Sensitive data leaks caused by misconfigurations can lead to incident response expenses and regulatory fines.

Preventing Unexpected Expenses:

Proactively address these key areas to avoid surprises in your Lambda bill:

  • Secrets Sprawl: API keys, tokens, and credentials accidentally left in your code or configuration become easy targets for abuse.
  • Public Blindspots: Exposed code in repositories or other external sources can reveal exploitable weaknesses, increasing risk.
  • Policy Gaps: Without consistent security checks integrated into your development process, costly misconfigurations can quickly become part of your deployed Lambda functions.

Designing Effective Functions for AWS Lambda Cost Optimization

Optimizing your Lambda functions can make a huge difference in your AWS bill.  Here are the top 3 methods to help optimize AWS Lambda costs.

1. Function right-sizing

Finding the ideal memory allocation is the key to optimizing cost and performance in your Lambda functions. Too much, and you’ll overpay; too little, and your function’s performance will suffer.

  • Start Smart: Base your initial memory estimate on the function’s purpose.
  • Test and Refine: Use load testing and monitor execution logs. Check CloudWatch metrics (especially MemorySize and Duration) and adjust your memory allocation accordingly.
  • Simplify the Process: Finding the perfect memory configuration can be time-consuming. Powered by AWS Step Functions, the AWS Lambda Power Tuning tool makes optimization easier by automating testing across different memory settings and analyzing your function’s performance. This process helps you quickly pinpoint the most cost-effective and efficient configuration for your needs.
AWS Lambda Power Tuning Results

2. Request invocation optimization

Amazon charges you each time your Lambda function runs (invocations). Here’s how to minimize those calls and reduce costs:

  • Batch Requests: Group multiple requests together to reduce overhead.
  • Use Queues: Services like SQS or Kinesis let you manage the flow of requests, preventing function overload.
  • Cache Responses: Store frequently used results to avoid repeated calculations.
  • Minimize Cold Starts: These initial function runs can be expensive, so design strategically to reduce their frequency.

3. Employing best practices in your code

More efficient code is always better than efficient code. That said, there’s only so much time developers should be spending on making code cost-effective once it runs. 

You can improve application performance and lower costs with a helpful Amazon tool called CodeGuru Profiler. This helpful tool identifies your application’s most “expensive” lines of code and provides recommendations to optimize your application for reduced AWS Lambda expenses.

Monitoring and Analyzing Your Lambda Usage

AWS Lambda’s usage-based pricing can lead to unexpected expenses if left unchecked.  Closely monitoring your usage metrics is essential for budget control and optimization.  Fortunately, AWS automatically tracks these metrics through its CloudWatch service.

CloudWatch provides valuable data to help you understand and manage your Lambda costs:

  • Key Metrics: This tool tracks the total number of requests, execution duration per request, and error rates. This data is crucial to understanding how your functions perform and where you incur costs.
  • Visualizations: The Lambda console offers graphs of these metrics, making it easy to spot trends and anomalies.
  • Customization: You can filter results (by time range, time zone, etc.) and create custom metrics relevant to your specific use case.

This data empowers you to:

  • Refine Cost Estimates: Adjust your forecasts based on real-world usage patterns.
  • Optimize Memory Allocation: Ensure you allocate the right amount of memory to avoid overpaying.
  • Consider Alternatives: If Lambda’s pricing model isn’t cost-effective for your workload, explore other deployment options.
  • Troubleshoot Performance: Identify code inefficiencies or issues that might impact your functions and drive up costs.
AWS Lambda Power Tuning Results

Leveraging Reserved Concurrency for AWS Lambda Cost Management

For functions with predictable usage patterns, consider Lambda Reserved Concurrency. This feature lets you set a maximum number of concurrent instances for a function, ensuring consistent performance even during traffic surges.

Seems counterintuitive, Right?  At first, it might seem more expensive to have instances always running. However, in specific situations, Reserved Concurrency can save you money and prevent these problems:

  • Performance Issues: Avoid slowdowns or errors caused by scaling limitations.
  • Unexpected Costs: Prevent sudden spikes from generating a much higher bill.

Implementing AWS Lambda Cost Alarms and Budgets

Analyzing Lambda costs through CloudWatch can be a time-sink, especially when you have many small functions across different applications. Luckily, there are tools to help you stay informed without manually checking CloudWatch all the time.

  • How Billing Alarm works: You define a Billing Alarms threshold for your AWS account (or specifically for Lambda). If your expenses reach or exceed this amount, you’ll receive an alert (usually via email or SNS notification).
  • They’re helpful: Billing alarms give you an early warning system for unexpected cost increases. This alarm lets you identify potential issues before they lead to a massive bill shock.
  • Example: Set an alarm for 80% of your expected Lambda costs. If it triggers, you can investigate load patterns, optimize functions, or adjust your forecasts.


  • How Budgets work: Budgets let you set spending targets and track your actual costs against them. You can define budgets for your overall AWS account, specific services (like Lambda), or individual resources.
  • Why they’re helpful: Budgets offer more proactive control than simple alarms. They provide ongoing visibility into your spending trends, helping you stay within your financial limits.
  • Customization: You can configure alerts to trigger at different percentages of your budget, giving you flexibility based on your risk tolerance.

Alarms and budgets complement each other nicely. Alarms are great for sudden spikes, while budgets provide long-term tracking. Set broad alarms and budgets initially, then refine them as you better understand your Lambda usage patterns.

Weed out AWS misconfigurations with Spectral

Balancing cost and security in AWS Lambda can be a constant challenge. Misconfigurations and exposed secrets can quickly lead to skyrocketing costs or severe breaches.

Spectral simplifies this process. This developer-centric solution proactively addresses risks, empowering you to use Lambda confidently. It integrates seamlessly into your workflow, detecting misconfigurations, uncovering hidden secrets, and even scanning external sources for vulnerabilities – ensuring both security and cost-efficiency.

Ready to try Spectral? Start with a free account.

Related articles

The Developer's Essential Guide to Cloud Deployment Models

The Developer’s Essential Guide to Cloud Deployment Models

You’ll probably agree that there are barely any organizations left that don’t use some form of cloud computing in their daily operations. In fact, the cloud

6 Steps for Success with CI/CD Security Hardening

6 Steps for Success with CI/CD Security Hardening

Rapid digitalization and increasing remote business operations place a significant burden on developers, who are continuously pressured to push out software faster. As a result, CI/CD

The Developer's Checklist to Security Hardening

The Developer’s Checklist to Security Hardening [XLS Download]

The coming of the internet was a beautiful thing, bringing about accessibility to reach everyone across the globe. But this reach is a double-edged sword. If

Stop leaks at the source!