System Design Calculator

Estimate RPS, storage, bandwidth and see the formulas behind.

ENRU
Input parameters
Daily Active Users (DAU)
How many unique users actively use your system per day. Typical range: 1k–10M. Default here: 1,000,000.
Requests per user per day
Average number of requests (API calls, page loads, actions) one active user makes per day. Typical: 5–100. Default: 20.
Peak multiplier (burst factor)
How many times peak load is higher than average (for example, in the evening or during campaigns). Typical: 5–20. Default: 10.
Reads (%)
Share of read operations among all operations at peak load. Many systems are read-heavy. Typical: 80–99%.
Writes (%)
Share of write operations. Usually 1–20%. By default this is just 100% − reads%. (10% auto if reads = 90%)
Payload per read
Approximate amount of data read from storage per read operation. Small API payloads are often 0.1–10 KB. Default: 0.5 KB.
Payload per write
Approximate amount of data written to storage per write operation. Default: 1 KB.
Response size
Average size of the response that your backend returns to the client. Default: 4 KB.
Retention (days)
How many days of data you plan to store for this workload. Typical values: 7, 30, 90 days. Default here: 30.
Results & formulas
Average RPS
231.48 RPS
Formula: Average RPS = (Daily active users × Requests per user per day) / 86,400 (seconds in a day)
Example: avgRps ≈ (1M × 20) / 86,400 = 231.48
Peak RPS
2.3K RPS
Formula: Peak RPS = Average RPS × Peak multiplier
Example: peakRps ≈ 231.48 × 10 = 2.3K
Read RPS
2.1K RPS
Formula: Read RPS = Peak RPS × (Share of reads in percent / 100)
Example: readRps ≈ 2.3K × (90 / 100) = 2.1K
Write RPS
231.48 RPS
Formula: Write RPS = Peak RPS × (Share of writes in percent / 100)
Example: writeRps ≈ 2.3K × (10 / 100) = 231.48
Per day
19.07 GB / day
Formula: Daily storage = Write RPS × Payload per write (in bytes) × 86,400 seconds
Example: dailyStorage ≈ 231.48 × 1 KB × 86,400 ≈ 19.07 GB
Retention period total
572.20 GB
Formula: Retention storage ≈ Daily storage × Number of retention days
Example: monthlyStorage ≈ 19.07 GB × 30 ≈ 572.20 GB
Per 365 days
6.80 TB
Formula: Yearly storage ≈ Daily storage × 365 days
Example: yearlyStorage ≈ 19.07 GB × 365 ≈ 6.80 TB
Inbound (requests)
1.24 MB/s
Formula: Inbound bandwidth ≈ Read RPS × Payload per read + Write RPS × Payload per write
Example: inbound ≈ readRps × payloadRead + writeRps × payloadWrite ≈ 1.24 MB/s
Outbound (responses)
9.04 MB/s
Formula: Outbound bandwidth ≈ Peak RPS × Response size
Example: outbound ≈ peakRps × responseSize ≈ 9.04 MB/s

All numbers are back-of-the-envelope estimations to get the correct order of magnitude.