SCADA, Telemetry & Industrial Monitoring challenge
Twelve questions on historians, deadbands, time sync and the OT/IT boundary.
SCADA / OT · Professional Microtool
Historian Storage Calculator
Capacity · Growth · Retention
Estimate how much storage a process historian needs from tag count, sample interval, sample size, retention and the compression you expect to achieve — and see how the answer moves as you keep history for longer.
- —Archived tags
- —Sampled every
- —Uncompressed / day
- —Compression
- —Kept for
- —Storage
Start from an example: Mid-size plant, one-second data, one year online →
Full output
- —Growth per day
- —Growth per year
- —Before compression
- —Sample rate
Storage required against retention period
Storage grows in a straight line with retention, so the retention policy — not the tag count — is usually the decision that sets the bill.
Keep it
Both carry the figures you entered, in the part of the address that is never sent to a server. Share only where that is appropriate. To keep a copy for a project file, print the page — it lays itself out as a document.
Need sizing based on the real SCADA configuration?
We can model the actual tags, update rates, retention and replication — and turn the sizing into something your team reruns as the plant changes, instead of a spreadsheet nobody trusts.
Calculation basis 4 steps · view the method →
Samples per second = archived tags ÷ sample interval—Uncompressed per day = samples per second × bytes per sample × 86,400 s—Uncompressed total = uncompressed per second × retention period—Storage required = uncompressed total ÷ compression ratio—
Assumptions & limitations Screening estimate for capacity planning and budgeting · 7 assumptions →
This is a screening estimate. Real archives depend on the compression actually achieved by your data, on indexes, replication and backups, and on how the product stores its files. Confirm capacity with the vendor's sizing guidance and with measurements from a running archive before committing hardware.
- One average sample interval is applied to every tag; in practice fast and slow tags differ by orders of magnitude.
- The sample interval is the rate before compression; the deadband's effect belongs entirely in the compression ratio and must not be counted in both.
- Storage is expressed in decimal units, as disks are sold: 1 TB = 10¹² bytes.
- The compression ratio is applied uniformly across all tags.
- Indexes, replication, snapshots, backups and filesystem overhead are excluded.
- Event, alarm and batch records are excluded — these are usually small next to time-series data, but not always.
- The archive is assumed to run at a steady state, with no backfill or reprocessing.
Worked examples
- Mid-size plant, one-second data, one year online
Open with these figures → - High-rate subset, 100 ms data, 90 days online
Open with these figures → - Wide but slow: 60,000 tags at one minute, five years
Open with these figures →
About this tool
Historian sizing is usually settled long before anyone measures a real archive, which is why it is so often wrong in both directions. This tool does the arithmetic explicitly — samples per second, bytes per day, total before and after compression — so the number can be argued with rather than accepted. It is written for control, operations and IT engineers planning or reviewing a historian.
Go deeper
Power & Utilities expertise
Cloud SCADA, distributed data acquisition and digital twins around real infrastructure.
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A pilot-ready enterprise platform for the electric-utility industry.