How fast is your computer, really? Numbers every programmer should know.
Your computer does things at wildly different speeds. Reading from memory? Nanoseconds. Reading from disk? Milliseconds. That's a million times slower! Knowing these rough numbers helps you build faster software without over-engineering.
If reading from CPU cache took 1 second, here's how long everything else would take:
Drag to rotate. Hover over arcs to see latency between cloud regions.
| Source | Destination | Distance | Latency | Bandwidth |
|---|---|---|---|---|
| 🇺🇸 US East | 🇺🇸 US Central | 1,500 km | 25ms | ~25 MB/s |
| 🇺🇸 US Central | 🇺🇸 US West | 2,400 km | 40ms | ~25 MB/s |
| 🇺🇸 US East | 🇺🇸 US West | 3,700 km | 60ms | ~25 MB/s |
| 🇮🇪 EU West | 🇩🇪 EU Central | 1,100 km | 20ms | ~25 MB/s |
| 🇺🇸 US East | 🇮🇪 EU West | 5,900 km | 80ms | ~25 MB/s |
| 🇺🇸 US Central | 🇮🇪 EU West | 6,800 km | 100ms | ~25 MB/s |
| 🇹🇼 Asia East | 🇯🇵 Tokyo | 2,100 km | 50ms | ~25 MB/s |
| 🇹🇼 Asia East | 🇸🇬 Singapore | 3,200 km | 70ms | ~25 MB/s |
| 🇸🇬 Singapore | 🇦🇺 Sydney | 6,300 km | 100ms | ~25 MB/s |
| 🇺🇸 US East | 🇧🇷 São Paulo | 7,700 km | 120ms | ~25 MB/s |
| 🇺🇸 US West | 🇹🇼 Asia East | 10,500 km | 140ms | ~25 MB/s |
| 🇺🇸 US West | 🇦🇺 Sydney | 12,100 km | 150ms | ~25 MB/s |
| 🇮🇪 EU West | 🇸🇬 Singapore | 10,800 km | 160ms | ~25 MB/s |
| 🇺🇸 US West | 🇸🇬 Singapore | 13,600 km | 180ms | ~25 MB/s |
Light travels ~200 km/ms in fiber optic cable. A 10,000 km route has a theoretical minimum of ~50ms one-way, ~100ms round-trip. Real-world latency is higher due to routing, switching, and protocol overhead.
Interactive visualization of regions, availability zones, and network latencies. Click on elements to see details. Packets animate between nodes to show relative speeds.
This simulation shows how data centers are organized into regions (geographic areas) containing multiple availability zones (isolated data centers). Packets animate between nodes to visualize relative network speeds.
| Connection Type | Distance | Latency | Bandwidth | Cost |
|---|---|---|---|---|
| 🟢 Same AZ (intra-zone) | <1 km | <0.5ms | 10+ Gbps | Free |
| 🟡 Cross-AZ (same region) | 10-100 km | 1-2ms | 5-10 Gbps | $0.01/GB |
| 🔴 Cross-Region (same continent) | 1,000-4,000 km | 20-60ms | ~25 MB/s | $0.02/GB |
| 🔴 Cross-Region (intercontinental) | 5,000-12,000 km | 80-180ms | ~25 MB/s | $0.05-0.10/GB |
Memorize these. They'll help you estimate if your system design makes sense.
If a CPU cycle (0.3ns) was 1 second:
Cloud pricing for the things you care about (monthly, on-demand):
| Resource | Amount | Price | With Commitment |
|---|---|---|---|
| ☁️ CPU (1 vCPU) | 1 core | $15/mo | $10/mo |
| 🧠 Memory | 1 GB | $2/mo | $1/mo |
| 🪣 Blob Storage (S3) | 1 GB | $0.02/mo | - |
| 💿 SSD (Zonal) | 1 GB | $0.20/mo | - |
| 🌐 Network Egress | 1 GB | $0.10 | - |
| 📊 Logs/Traces | 1 GB | $0.50 | - |
| 🎮 GPU | 1 GPU | $5,000/mo | $3,000/mo |
Logging costs: 100k requests/sec × 1KB each = 100MB/sec = 8.6TB/day = ~$4,300/mo in log storage alone!
Egress trap: Serving 1 PB/month to users = $100,000 in egress fees 😱
If your estimate needs more than 6 assumptions, you're overcomplicating it.
GB/s × seconds = GB. Units are your sanity check.
Is it ~10ms or ~100ms? That's what matters, not 47ms vs 52ms.
Break big questions into smaller guessable pieces.