cloudcostdown.euAWS CloudFront Cost Optimization · CDN Guide
How to Reduce AWS CloudFront Costs and Data Transfer Bills
CloudFront includes 1TB/month free and can replace expensive direct S3 or EC2 data transfer. Most teams either aren’t using it where they should, or have misconfigured cache policies that reduce its effectiveness.
4 CloudFront Cost Optimizations
Start with cache hit ratio - a low ratio is the fastest indicator of overspending.
Maximize cache hit ratio
Every cache miss triggers an origin fetch - charged at S3 or EC2 data transfer rates ($0.09/GB to internet). A 50% cache hit ratio means half your content is being served from cache for free. Optimizing cache policies, TTLs, and cache key configuration can push this to 80–90% for most workloads.
How to implement
- Check current cache hit ratio: CloudWatch → CloudFront → CacheHitRate metric per distribution
- Increase default TTL for static assets: set Cache-Control: public, max-age=31536000 on images, JS, CSS
- Reduce cache key cardinality: don't include unnecessary headers or query strings in the cache key
- Use CloudFront Cache Policies instead of legacy forwarding behaviors for better control
- For dynamic content with auth: use Origin Request Policy to pass cookies to origin without including them in the cache key
Note: A cache hit ratio below 60% usually indicates either very short TTLs or a cache key that varies on unnecessary dimensions (e.g., forwarding all query strings when only a subset affects the response).
Enable Origin Shield to reduce origin load and transfer costs
Origin Shield adds an additional caching layer between edge locations and your origin. Without Origin Shield, each edge location that misses cache fetches independently from your origin - resulting in many origin requests for the same object. Origin Shield consolidates these, dramatically reducing origin traffic.
How to implement
- CloudFront console → Distribution → Origins → Edit → Enable Origin Shield
- Select the Origin Shield region closest to your origin (e.g., us-east-1 for US East origins)
- Origin Shield pricing: $0.0075–$0.0150 per 10,000 requests - much cheaper than origin data transfer
- Monitor origin request reduction in CloudFront metrics: OriginRequests vs. Requests ratio
- Particularly valuable if origin is RDS, ALB, or EC2 - Origin Shield reduces load on the origin server
Note: Origin Shield is most valuable when you have many CloudFront edge locations serving the same content globally and your origin is bandwidth-constrained or expensive to scale.
Select the right CloudFront price class
CloudFront data transfer pricing varies by edge location - North America and Europe are cheapest, Asia-Pacific and South America are 2–3× more expensive. If your users are primarily in the US and Europe, switching from Price Class All to Price Class 100 (US/Canada/Europe) cuts transfer costs 30–50%.
How to implement
- Check your CloudFront geographic breakdown: CloudFront console → Distribution → Monitoring → Viewers by geography
- If 90%+ of traffic is from US/Canada/Europe: set Price Class 100
- If significant APAC traffic: evaluate Price Class 200 (all regions except South America)
- Price Class All is only worth it if you have meaningful traffic from South America, Africa, or Middle East
- CloudFront console → Distribution → Edit → Price Class
Note: Price Class selection is a 5-minute change that can cut CF costs by 30–50% for startups with primarily North American or European user bases.
Use CloudFront in front of S3 to replace internet data transfer
S3 data transfer to internet costs $0.09/GB. CloudFront data transfer from S3 origin to CloudFront edge is free (same-region). CloudFront charges $0.0085–$0.085/GB to deliver to users - typically 50% cheaper than direct S3 transfer. For static sites and media-heavy applications, this is a significant saving.
How to implement
- Create a CloudFront distribution with S3 as origin
- Enable Origin Access Control (OAC) to restrict S3 access to CloudFront only - block direct S3 public access
- Update your S3 bucket policy to allow only the CloudFront OAC principal
- Update DNS CNAME to point to the CloudFront distribution
- Set long TTLs on static assets and use cache invalidation on deployments (first 1,000 paths/month free)
Note: Transfer from S3 to CloudFront within the same region is free. CloudFront then delivers to users at CDN rates ($0.0085–$0.085/GB depending on region), which is cheaper than S3 direct for most global audiences.
Frequently Asked Questions
How much does CloudFront cost?
CloudFront charges for data transfer out ($0.0085–$0.085/GB depending on region), HTTP requests ($0.0075–$0.0150 per 10,000 HTTPS requests), and Origin Shield ($0.0075–$0.0150 per 10,000 requests). The free tier includes 1TB of data transfer and 10 million HTTP/HTTPS requests per month.
Is CloudFront cheaper than direct S3 for content delivery?
Usually yes, for global audiences. S3 direct internet transfer is $0.09/GB everywhere. CloudFront to US/Europe is $0.0085/GB - 10× cheaper. CloudFront also serves content from edge locations closer to users, reducing latency. The break-even is quickly reached for any significant traffic volume.
What is CloudFront Origin Shield?
An additional caching layer between CloudFront’s global edge network and your origin. Without it, each edge location fetches independently from your origin on cache misses. Origin Shield routes all cache misses through a single region, dramatically reducing origin requests. Pricing is $0.0075–$0.0150 per 10,000 requests.
Does CloudFront work with ALB and EC2 origins?
Yes. CloudFront supports any HTTP/HTTPS origin: S3, ALB, EC2, API Gateway, or custom origins. For dynamic content, CloudFront can cache based on your defined TTL and cache key. Even a short TTL (e.g., 5 seconds) dramatically reduces origin load during traffic spikes.
How do I check my CloudFront cache hit ratio?
CloudWatch → CloudFront → select your distribution → CacheHitRate metric. Values below 60% warrant investigation. The CloudFront console also shows a traffic breakdown under the Monitoring tab, including request volume per edge location and cache hit/miss breakdown.