Capacity planning.

also: headroom · capacity headroom

Measuring current limits, forecasting demand and adding capacity ahead of it, keeping headroom: the spare share of maximum capacity.

the two-minute refresher

Headroom = (max capacity − current usage) ÷ max capacity: 3,000 QPS max at 2,000 QPS = 33%.
Find limits with load tests; find the bottleneck before it finds you.
Forecast growth and plan lead time: hardware, quotas and migrations take weeks.
Keep critical resources below 70-80% utilisation; latency explodes near 100%.

also: headroom · capacity headroom

Measuring current limits, forecasting demand and adding capacity ahead of it, keeping headroom: the spare share of maximum capacity.

Headroom = (max capacity − current usage) ÷ max capacity: 3,000 QPS max at 2,000 QPS = 33%.
Find limits with load tests; find the bottleneck before it finds you.
Forecast growth and plan lead time: hardware, quotas and migrations take weeks.
Keep critical resources below 70-80% utilisation; latency explodes near 100%.