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Backup Encryption Time Calculator

Work out backup encryption time instantly with clear inputs, formula shown and shareable results.

About Backup Encryption Time Calculator

With AES-NI, encryption throughput reaches several gigabytes per second per core, so it is rarely the bottleneck in a backup pipeline — disk or network usually is. Without hardware acceleration, software AES runs at a fraction of that speed and becomes the limiting stage, which is when ChaCha20-Poly1305 becomes the better choice. Parallel streams help until memory bandwidth saturates, modelled here at 16 streams.

Formula

Encryption time

effective throughput = base x cipher factor x min(streams, 16); time = data bytes / effective throughput

Worked example

With the default values below, Backup Encryption Time Calculator returns Encryption time of 5,556. Change any input above and every figure here is recalculated in your browser.

Inputs used

Data to encryptminimum 0.001 TB
20 TB
Encryption throughputminimum 1 MB/s
900 MB/s
Parallel streamsaccepts 1–128
4
Cipherone of AES-256-GCM with AES-NI, AES-256 in software, ChaCha20-Poly1305
AES-256-GCM with AES-NI

Results

Encryption time
5,556 s
Effective throughput
3,600 MB/s
Encryption time in hours
1.54 h
Throughput relative to hardware AES
100%

Step by step

  1. 1Values used
  2. 2Encryption time
  3. 3Encryption time= 5,556 s
  4. 4Effective throughput= 3,600 MB/s
  5. 5Encryption time in hours= 1.54 h
  6. 6Throughput relative to hardware AES= 100

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

Should backups be encrypted before or after compression?

Compress first. Encrypted data is indistinguishable from random and will not compress at all, so reversing the order can multiply storage cost.

Does encryption slow restores as much as backups?

Decryption is comparable in cost to encryption for AES-GCM, so plan the same overhead on restore — which matters because restore time is what your recovery objective is measured against.

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