Question 1

How do I estimate bandwidth for my application?

Accepted Answer

Measure first: use browser DevTools Network tab to measure actual data transferred in a typical session. For a web app: load the page (typically 1–5MB), then add ongoing API calls (0.1–0.5MB per minute of active use). For video: use bitrate × duration (1080p at 4Mbps = 30MB/minute). Add 20–30% headroom for protocol overhead, analytics, and error tracking traffic.

Question 2

What is a good CDN for reducing bandwidth costs?

Accepted Answer

CDN comparison by cost and features: Cloudflare (free tier: unlimited bandwidth, paid from $20/mo): Best value for most apps. BunnyCDN ($0.01–$0.06/GB): Cheapest pure CDN. AWS CloudFront ($0.085/GB): Integrates best with AWS stack. Fastly ($0.12/GB): Best for real-time APIs. Bunny CDN is 85% cheaper than CloudFront for the same traffic. For most startups, Cloudflare free tier covers millions of requests at zero CDN cost.

Question 3

What bandwidth causes the most cost surprises?

Accepted Answer

Video and image-heavy content causes the biggest surprises. A site with 1,000 daily users viewing 5MB hero images each = 5GB/day = 150GB/month. At AWS pricing ($0.085/GB), that's $12.75/month — reasonable. But 10,000 DAU with video content (200MB/user) = 60TB/month = $5,100/month in egress alone. Always implement lazy loading, image compression (WebP saves 25–34%), and aggressive CDN caching for media.

Question 4

How do peak traffic spikes affect bandwidth costs?

Accepted Answer

Most CDN providers bill on the 95th percentile bandwidth for monthly plans, or actual data transfer for pay-per-GB plans. A 3× daily peak means you need 3× more server capacity for that period. If you're on pay-per-GB CDN pricing, traffic spikes (news coverage, viral posts) can spike your monthly bill by 5–20× without warning. Use auto-scaling and set billing alerts at 50% and 80% of your monthly budget.

Question 5

Should I use a CDN for my application?

Accepted Answer

Yes — almost always. CDN benefits: (1) Latency reduction: serving from edge locations nearest to users reduces load time by 40–70%, (2) Cost reduction: CDN egress is typically 60–80% cheaper than origin server egress, (3) DDoS protection: included with Cloudflare, (4) Reduced origin load: CDN caches static assets, reducing requests to your server by 80–95% for typical apps. Even for APIs, CDN caching of semi-static responses can dramatically reduce cost and latency.

Bandwidth Usage Calculator — Monthly Data Transfer & CDN Cost Estimator

Frequently Asked Questions

From the Blog