Estimation Lab
Back-of-the-envelope math is a learnable skill. Work each drill yourself first, then reveal the step-by-step derivation. The numbers on the right are worth memorizing cold.
How much storage for 5 years of tweets at 500M tweets/day?
500M tweets/day~300 bytes per tweet (text + metadata)5 years retention
What egress bandwidth does a video site need for 1M concurrent 1080p streams?
1M concurrent viewers1080p ≈ 5 Mbps per stream
What peak QPS should you plan for from 100M daily requests?
100M requests/dayTraffic is uneven — assume peak is ~3x average
How much RAM to cache the hot 20% of 1B objects at 1KB each?
1B objects1 KB per object80/20 rule — cache the hot 20%