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Container vs VM Overhead Calculator

Work out container vs vm overhead instantly with clear inputs, formula shown and shareable results.

About Container vs VM Overhead Calculator

Every VM carries a full guest operating system — typically 512 MB or more of kernel, init and services — while containers share the host kernel and add only a few megabytes of runtime state. Across sixty small workloads that is roughly 30 GB of duplicated operating system, which is the core density argument for containers over VMs.

Formula

Overhead comparison

VM total = workloads x (workload memory + guest OS memory); container total = workloads x (workload memory + runtime overhead) + one shared kernel

Worked example

With the default values below, Container vs VM Overhead Calculator returns Memory saved by containers of 27.46 GiB. Change any input above and every figure here is recalculated in your browser.

Inputs used

Workloads to runminimum 1
60
Memory per workloadminimum 1 MB
400 MB
Guest OS memory per VMminimum 1 MB
512 MB
Container runtime overhead per containerminimum 0 MB
12 MB

Results

Memory saved by containers
27.46 GiB
Memory with one VM per workload
50.96 GiB
Memory with containers on a shared kernel
23.50 GiB
Overhead reduction
53.9%

Step by step

  1. 1Values used
  2. 2Overhead comparison
  3. 3Memory saved by containers= 29,488,000,000
  4. 4Memory with one VM per workload= 54,720,000,000
  5. 5Memory with containers on a shared kernel= 25,232,000,000
  6. 6Overhead reduction= 53.9

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 or compounding frequency into account.
  • Figures are rounded for display to 1 decimal place, 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

Do containers give the same isolation as VMs?

No. They share the host kernel, so a kernel vulnerability crosses the boundary. VMs, or sandboxed runtimes such as gVisor and Kata, give stronger isolation.

When is a VM per workload still right?

For untrusted multi-tenant code, for workloads needing a different kernel or kernel modules, and where regulatory separation is mandated.

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