AWS EC2 Cost Estimator
Estimate your monthly AWS EC2 instance costs based on instance type, hours of usage, and storage. Plan your cloud compute budget accurately.
Spot Instance Savings Calculator
Calculate savings from using spot or preemptible instances. Factor in interruption rates to estimate real-world cost benefits.
$/hr
$/hr
%
% spot
$/hr
min
Pure On-Demand Cost⧉
$2,686.40
20 instances at $0.184/hr
Spot Strategy Cost⧉
$1,057.05
18 spot + 2 on-demand
Monthly Savings⧉
$1,629.35
60.65% reduction
Annual Savings⧉
$19,552.21
Projected yearly savings
Effective Blended Rate⧉
$0.0724/hr
Spot discount: 70.11%
Interruption Overhead⧉
$65.71
~0.9 interruptions/mo
Savings vs Risk
Savings: 60.65%
Risk Score: 10/100
Cost Breakdown
| Component | Monthly Cost | Share |
|---|---|---|
| Spot Compute | $722.70 | 68.37% |
| On-Demand Portion | $268.64 | 25.41% |
| Wasted (Interruptions) | $0.00 | 0.00% |
| Checkpointing | $65.70 | 6.22% |
| Fallback Cost | $0.01 | 0.00% |
| Total | $1,057.05 | 100% |
Interruption Rate Sensitivity
| Interruption Rate | Est. Interruptions/mo | Adjusted Cost | Savings | Savings % |
|---|---|---|---|---|
| 2% | 0.4 | $1,057.04 | $1,629.36 | 60.7% |
| 5% | 0.9 | $1,057.05 | $1,629.35 | 60.7% |
| 10% | 1.8 | $1,057.06 | $1,629.34 | 60.7% |
| 15% | 2.7 | $1,057.07 | $1,629.33 | 60.7% |
| 20% | 3.6 | $1,057.08 | $1,629.32 | 60.7% |
| 30% | 5.4 | $1,057.10 | $1,629.30 | 60.7% |
Planning notes, formulas, and examples
About the Spot Instance Savings Calculator
Spot instances (AWS), preemptible VMs (GCP), and spot VMs (Azure) offer massive discounts of up to 90% compared to on-demand pricing. The catch is that the cloud provider can reclaim these instances at any time, typically with a 2-minute warning.
This calculator helps you estimate actual savings from spot pricing by factoring in the interruption rate. If your workload gets interrupted 10% of the time and needs to restart, the effective savings are lower than the headline discount suggests. Enter on-demand and spot prices along with expected interruption rates to see realistic cost projections.
Spot instances are ideal for batch processing, CI/CD pipelines, data analysis, rendering, and any workload that's fault-tolerant and can handle interruptions. This calculator helps you quantify the cost benefit so you can make an informed decision.
When This Page Helps
Spot pricing can save 60–90% on compute costs, but the actual savings depend on interruption frequency and the cost of restarting jobs. It gives a realistic savings estimate that accounts for interruptions, helping you decide whether spot instances are worth the operational complexity for your specific workload.
How to Use the Inputs
- Enter the on-demand hourly rate for your instance type.
- Enter the current spot price (check your provider's spot pricing history).
- Set the expected interruption rate as a percentage.
- Enter the number of hours per month you need the capacity.
- Enter the number of instances in your spot fleet.
- Review the adjusted savings accounting for interruptions.
Formula used
Effective Spot Cost = spot_price × hours × (1 + interruption_rate × restart_overhead)
On-Demand Cost = on_demand_price × hours
Savings = (On-Demand Cost − Effective Spot Cost) × instancesExample Calculation
Result: $478.95 saved/month
On-demand: $0.10 × 730 × 10 = $730/month. Spot with 5% interruption overhead: $0.03 × 730 × 1.05 × 10 = $230.00. Monthly savings: $500/month (68% reduction). Even with occasional interruptions, spot instances deliver substantial savings.
Tips & Best Practices
- Diversify across multiple instance types and AZs to reduce interruption frequency.
- Use spot fleet or managed instance groups for automatic capacity replacement.
- Set a maximum price close to on-demand to avoid price spikes reclaiming your instances.
- Design workloads to checkpoint progress so interrupted jobs can resume rather than restart.
- Combine spot instances with a small on-demand baseline for critical capacity.
- Monitor spot price history to identify the most stable instance types in your region.
How Spot Pricing Works
Spot instances use spare cloud capacity that would otherwise sit idle. Providers offer this capacity at steep discounts to recover some revenue. When demand for the capacity rises, spot instances are reclaimed. This creates a dynamic marketplace where prices and availability fluctuate based on supply and demand.
Designing for Interruptions
The key to using spot instances effectively is building interruption tolerance into your architecture. This means checkpointing long-running jobs, using message queues to track work items, designing for idempotent operations, and leveraging auto-scaling to replace interrupted capacity automatically.
Spot Fleet Strategies
Rather than requesting a single instance type, spot fleets let you specify multiple instance types and availability zones. The fleet automatically selects the most cost-effective and available options, reducing both cost and interruption risk. AWS Spot Fleet, GCP managed instance groups, and Azure spot VM scale sets all support this pattern.
Sources & Methodology
Last updated:
Frequently Asked Questions
It varies significantly by instance type and region. Some instance types see less than 5% interruption rates while others exceed 20%. AWS publishes interruption frequency data in the Spot Instance Advisor. Diversifying across types keeps effective rates low.
Headline discounts range from 60–90% off on-demand pricing. After accounting for interruptions and restart overhead, real-world savings typically range from 50–80%. The exact savings depend on your workload's ability to handle interruptions.
Batch processing, CI/CD pipelines, data analytics, rendering, machine learning training, testing environments, and any workload that can tolerate interruptions. Stateless web servers behind auto-scaling groups can also use spot effectively.
You receive a 2-minute warning (on AWS) before the instance is terminated. Your application should handle graceful shutdown, checkpoint progress, and re-queue incomplete work. The instance is stopped or terminated depending on your configuration.
Yes, and this is a best practice. Run your minimum required capacity on on-demand or reserved instances, and use spot instances for additional capacity. Auto Scaling groups can manage this mix automatically.
No, spot prices vary by region, Availability Zone, and instance type based on supply and demand. Less popular regions and instance types tend to have lower prices and fewer interruptions.
More in this topic
Reserved vs On-Demand Savings Calculator
Compare reserved instance pricing against on-demand rates. Calculate savings from 1-year and 3-year commitments on AWS, Azure, or GCP.
Cloud Cost Optimization Calculator
Calculate potential savings from cloud cost optimization strategies like rightsizing, reserved instances, and spot usage. Quantify your optimization ROI.