Server RAM Calculator
Estimate the RAM a web server needs from concurrency, worker count and per-process memory.
Not sure how much RAM to provision for a web or API server? This server RAM calculator takes the number of worker processes, memory per worker, OS/base overhead, an extra reserve for cache/DB, and a safety headroom (%), then computes the recommended memory and rounds it up to the nearest common RAM tier among 1, 2, 4, 8, 16, 32 and 64 GB.
It is handy for picking a VPS or cloud instance size, or for setting a container memory limit. To also weigh the cost as traffic grows, pair it with the bandwidth cost calculator, and to translate an availability target into allowed downtime use the SLA calculator.
| Workers total (MB) | 1,024 |
|---|---|
| Subtotal (MB) | 2,048 |
| With headroom (MB) | 2,457.6 |
| Recommended RAM tier | 4 GB |
How it is calculated
The tool derives the recommended memory in this order.
- Workers total = workers × memory per worker (MB)
- Subtotal = OS overhead + workers total + cache/DB reserve
- With headroom = subtotal × (1 + safety headroom% ÷ 100)
- Recommended tier = round the with-headroom value up to the next tier among 1, 2, 4, 8, 16, 32, 64 GB
Where memory per worker comes from
Memory per worker should come from real application profiling, not a guess. Observe the resident set size (RSS) of your processes under load and add margin on top of the peak. Multi-process models such as PHP-FPM, Gunicorn, or a Node cluster simply add up as workers × memory per worker.
Cache and DB often dominate
When a database or in-memory cache (Redis, Memcached) runs on the same box, it frequently consumes far more memory than the worker total. If you allocate 4 GB to a Redis cache, enter 4096 MB as the cache/DB reserve. If you move the database to a separate server, set this reserve to 0.