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Docker Log Growth Calculator

Project disk usage growth from container logs based on volume and retention settings.

About Docker Log Growth Calculator

Container log growth = containers × min(logRate × 1440 × retentionDays / 1024, maxFileSize). Docker's --log-opt max-size caps per-container log files, causing rotation. Without caps, verbose containers can consume disk rapidly.

Formula

Log Disk

disk = containers × min(logRate × minutesPerDay × retention / 1024, maxSize)

containers
Number of logging containers
logRate
KB/min log output
retention
Days of retention
maxSize
Docker max-size cap in MB

Worked example

With the default values below, Docker Log Growth Calculator returns Total Log Disk Usage of 2.40. Change any input above and every figure here is recalculated in your browser.

Inputs used

Number of Containersaccepts 1–100,000 containers
25 containers
Avg Log Rate per Containeraccepts 0.1–100,000 KB/min
10 KB/min
Log Retentionaccepts 1–365 days
7 days
Max Log File Sizeaccepts 1–10,000 MB
100 MB

Results

Total Log Disk Usage
2.40 GB
Per-Container Daily Logs
14.1 MB/day
Effective per Container (capped)
98 MB
Uncapped Total (no max-size)
2.40 GB

Step by step

  1. 1Daily logs per container= 14.1MB/day
  2. 2Retention period per container= 98MB
  3. 3Capped by max-size= 98MB
  4. 4Total disk across all containers= 2.40GB

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

What's the default log driver behavior without max-size?

Without --log-opt max-size, the json-file driver grows logs indefinitely until disk is full, which is a common cause of production outages on long-running containers.

How many rotated files does Docker keep?

Set via --log-opt max-file (default 1). Setting max-file=3 with max-size=100m keeps up to 300MB per container.

Related Calculators

Docker Log Growth Calculator | Calcrivo