What Is Spot Instance Advisor? A Beginner-Friendly Guide

Amazon Web Services (AWS) provides three types of Elastic Compute Cloud (EC2) instances: On-Demand Instances, Reserved Instances (RIs), and Spot Instances. EC2 On-Demand instances are the default and most expensive instances. RIs and Spot instances offer discounts of up to 72% and 90% on On-Demand instances, respectively.

Reserved Instances are long-term commitments that guarantee compute power for one or three years. Spot Instances tap into AWS’s unused EC2 capacity at steep discounts, but AWS can reclaim them when demand for that capacity rises. Such reclamation could interrupt your workloads, leaving applications running on those instances temporarily unavailable.

Interruptions can not only harm your less fault-tolerant workloads, but also hurt your monthly recurring revenue, customer retention, and overall growth. Fortunately, Spot Instance Advisor aims to help you avoid that.

What Is Spot Instance Advisor?

Spot Instance Advisor helps you find the most suitable pool of Spot Instances for your needs, with the lowest likelihood of interruption, while offering the greatest savings over On-Demand pricing.

AWS originally called this tool Spot Bid Advisor, back when Spot pricing relied on a competitive bidding system. In that model, you submitted a maximum bid price and could lose your instance if someone outbid you. AWS retired the bidding model in favor of a more stable, demand-based pricing approach.

Today, you simply pay the current market price for Spot capacity, which is always capped at the On-Demand rate for that instance type. Here’s what the old Bid Advisor interface looked like:

Under that old model, a lower outbid frequency meant your Spot Instance stayed available longer — until someone placed a higher bid.

The modern Spot Instance Advisor works differently. Instead of worrying about bid strategies, you focus on selecting instance types with low interruption frequencies and favorable savings percentages.

Using Spot Instance Advisor is different.

How Does Spot Instance Advisor Work?

Spot Instance Advisor provides Frequency of Interruption insights on each EC2 instance type. You can sort the frequency of interruption by ascending or descending order.

It also shows how much you could save by using Spot Instances instead of On-Demand. AWS displays the savings as the difference between On-Demand and Spot Instance pricing over the last 30 days, expressed as a percentage.

The Spot Instance Advisor lets you select the following details based on your Spot Instance EC2 compute needs.

The following is an example of how Spot Instance Advisor features work:

Notice how the tool provides the “less than percentage” figure for Frequency of Interruption. Here’s the deal. As interruption frequency decreases, Spot Instances will last longer, resulting in increased availability, fewer interruptions, and more persistent workload performance for you.

The frequency of interruptions will vary based on several factors, such as your operating system and availability zone selection.

After identifying the instances most and least likely to be interrupted, you will want to reconsider what types of workloads to run on the available Spot Instances. Instances with a low interruption frequency (under 5%) are suitable for a variety of Spot Instance use cases, including containerized workloads, CI/CD pipelines, big data processing, and web servers that can tolerate brief disruptions.

You can still use Spot Instances with a higher interruption frequency if you are running highly fault-tolerant workloads or quick jobs. Otherwise, you’ll want to distribute your workload across a broad range of AWS instance types to ensure high availability and sustain reliable system performance. For more on this approach, see our guide to EC2 cost optimization strategies.

Requesting Spot Instances. You submit a Spot Instance Request to purchase available Spot Instances at a discount. You can optionally specify the maximum price you are willing to pay per hour. If you don’t specify a price, the On-Demand price becomes the default maximum — and AWS recommends leaving this at the default for the best balance of availability and savings. Amazon EC2 will fulfill your request if capacity is available and your price meets or exceeds the current Spot price.

Amazon EC2 can hibernate, stop, or terminate your Spot Instance when it needs the capacity back. There are two scenarios for this:

In either case, Amazon EC2 issues a Spot Instance interruption notice, which gives the instance two minutes’ notice before being interrupted.

You can request a Spot Instance only once or persistently. The EC2 service automatically resends a persistent Spot Instance request when the Spot Instance linked to the request terminates.

The service generates and sends an Instance Rebalance Recommendation, a signal that indicates a Spot Instance is at high risk of interruption. The advance warning helps you to distribute your workloads among existing or new Spot Instances prior to the two-minute Spot Instance interruption notice.

Although AWS promises interruptions are rare, you do not want to take that risk with your less fault-tolerant workloads.

In addition, switching between instances can be inefficient and costly over the longer term. This makes sense when you consider that you get a mere two-minute interruption notice. You have to manually find, select, and switch to the best Spot instances for your workloads during that time. Obviously a lot of pressure.

Need we mention that the ideal instances have to be available in your Availability Zone, to begin with?

Perhaps you’ve faced a different frustrating scenario, like this engineer:

Credit: Stack Overflow forum

Best Practices for Running Spot Workloads

Although AWS reports that interruptions are relatively rare, you do not want to rely on luck with production-adjacent or less fault-tolerant workloads. A few proven strategies can significantly improve your Spot reliability.

Diversify across instance types and families. Rather than requesting a single instance type, specify multiple types that meet your compute requirements (for example, m5.xlarge, m5a.xlarge, m6i.xlarge, and c5.xlarge). This gives AWS more capacity pools to draw from, dramatically reducing your interruption risk. Aim for at least six to ten instance types across multiple Availability Zones.

Use Auto Scaling Groups or EC2 Fleet. These AWS services let you request Spot capacity across multiple instance types, sizes, and AZs with a single configuration. If one instance type gets interrupted, the group automatically launches a replacement from an alternative pool — keeping your fleet at target capacity with no manual intervention.

Choose the capacity-optimized allocation strategy. When configuring your fleet, the capacity-optimized (or price-capacity-optimized) allocation strategy automatically selects instance pools with the highest available capacity and lowest interruption probability, rather than simply choosing the cheapest option. This approach prioritizes workload stability over marginal price differences.

Design for graceful shutdown. Use the two-minute interruption notice and Rebalance Recommendations to checkpoint application state, drain connections from load balancers, and migrate workloads before termination occurs. AWS EventBridge can automate these responses so you don’t have to react manually under pressure.

If you are looking for a way to automate this entire process end-to-end, dedicated orchestration tools can take it even further.

Is There A Better Way to Optimize Spot Instances?

You can automate the process of selecting the best Spot Instances for your needs — confirming their availability in your AWS region, OS, and computing power — by using a Spot Instance orchestration tool. This eliminates much of the repetitive manual work and applies the best practices above automatically.

One such tool is Xosphere Instance Orchestrator.

Xosphere substitutes On-Demand Instances for Spot Instances whenever the latter are available and reasonably priced. The software continuously checks your environment to assess the cost-effectiveness of your current instances.

As Spot Instances become less and less economical, Xosphere intelligently replaces them with On-Demand Instances. No human intervention is required. This transition does not cause significant system performance deterioration or render your applications unavailable.

Xosphere also supports applications written in any language or platform, containers (Kubernetes, EKS, Mesos, ECS, Rancher), and your favorite data stores, including Elasticsearch, MySQL, Redis, and Cassandra.

Here’s more about how Xosphere works, so you can decide if it’s a good Spot Instance Advisor alternative.

Key takeaway: Xosphere automatically replaces Spot Instances with On-Demand Instances so that you don’t have to — all while optimizing for cost.

Software and pricing information last verified May 2026. Features, pricing, and availability may have changed. Please verify current details with vendors before making decisions.

Frequently Asked Questions About Spot Instances

Here are answers to common questions about Spot Instance Advisor, Spot Instances, and Spot optimization tools.

Are Spot Instances worth it?

When available, Spot Instances can reduce your EC2 compute costs by 50–90% compared to On-Demand pricing. The actual discount varies by instance type, region, and current demand, but most users realize savings in the 50–70% range. For fault-tolerant workloads like batch processing, data pipelines, and CI/CD, the economics are compelling.

When is it best to use Spot instances?

Spot Instances are ideal for workloads that can tolerate interruptions: batch processing, big data analytics, CI/CD build and test pipelines, containerized stateless services, rendering jobs, and machine learning training runs. They work best when combined with Auto Scaling Groups that can automatically replace interrupted instances.

Is Spot Instance Advisor free?

Yes. Spot Instance Advisor is a free tool included with your AWS account. No additional subscription or EC2-specific plan is required.

How often does Amazon EC2 reclaim Spot Instances?

Interruption frequency varies by instance type, Availability Zone, operating system, and current demand. Historically, the average interruption rate across all instance types has been under 5%. You can check real-time interruption data for specific instance types directly in the Spot Instance Advisor.

How long does a Spot instance interruption last?

Once an interruption occurs, that specific Spot capacity is reclaimed. Your instance will be stopped, hibernated, or terminated depending on your configured interruption behavior. You’ll need to request new Spot capacity or fall back to On-Demand to continue running your workload. Using persistent Spot requests or Auto Scaling Groups automates this replacement process.

How much does Xosphere Instance Orchestrator cost?

Pricing is per hour per Spot Instance. Here’s a DIY Spot Instance savings calculator to see how much you could save with Xosphere.

Does CloudZero monitor and optimize Spot Instance costs?

CloudZero gives you granular visibility into your cloud costs by aligning spending to the teams, products, features, and customers that drive it. Whether you run On-Demand, Reserved, or Spot Instances, CloudZero lets you see exactly where your compute dollars go — broken down by cost per customer, cost per feature, cost per environment, and more.

You can use this insight to identify which workloads would benefit most from Spot adoption, track whether your Spot strategy is actually delivering savings, and receive automated anomaly alerts via Slack or email when spending deviates from expectations.

to see how CloudZero can help you optimize your entire AWS costs in days, not months. In addition, we will connect you to a CloudZero Cost Intelligence Analyst who will help you get started like a pro.