Why scale by hot-tier share?

Hot tier is the expensive one (full resolution, fast query). Cold or rolled-up tiers cost a fraction. Scaling by hot share keeps the per-tag-year number realistic.

How do I get cost per tag-year?

Take last quarter's cloud historian bill, divide by tag count, and annualize. Common cloud historians land at 0.30 to 2.00 dollars per tag-year for hot tier.

Should I include egress?

Yes if egress is large. Either fold it into per-tag-year cost or add it to the fixed line. Pick one and be consistent.

How do I model a hybrid (cloud plus on-prem)?

Run this calculator for cloud and the data historian storage cost calculator for on-prem. Sum the totals and compare to a pure-cloud or pure-on-prem case.

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Cloud Historian Cost Calculator

Estimate annual cloud historian cost. Enter total tags ingested, cost per tag-year (storage plus query plus retention tier blend), the share of tags in the hot retention tier (full-resolution recent data), and a fixed cloud historian platform subscription. The calculator returns variable cloud spend and the loaded total.

What this calculator does

Estimate annual cloud historian cost from total tag count ingested, cost per tag-year (storage plus query plus retention tier), the share of tags in the hot retention tier, and a fixed cloud historian platform subscription.
Use it when a cloud architect is sizing AVEVA Data Hub, AWS IoT SiteWise, or a comparable cloud historian against an on-prem historian, or planning the next cloud bill.
It returns the annual cloud historian cost, broken into variable per-tag spend (weighted by hot-tier share) and a fixed platform subscription line.

Formula used

Variable cloud historian cost = tag count × cost per tag-year × hot-tier share
Total cloud historian cost = variable cost + fixed cloud subscription

Inputs explained

Tags ingested into cloud historian: Use the count of unique tags ingested (deduplicated, not counts of writes).
Cost per tag-year (storage plus query plus retention): Use the blended cost per tag-year from the cloud bill (storage plus per-query cost amortized plus retention tier blend).
Share of tags in hot retention tier: Use the share of tags kept at full resolution in the hot tier (typical 30 to 70 percent; the rest are downsampled or moved to cold tier).
Fixed cloud historian platform subscription: Use the annual cloud platform subscription, support, and admin labor amortized over the year.

How to use the result

Use it before signing a cloud historian contract, when comparing cloud against on-prem, or when planning a tier rebalance to move cold tags to lower-cost storage.
Cloud bills carry many small line items (egress, query, snapshot, alert). Build a true bill model from the cloud bill and use this calculator for first-pass sizing.

Common questions

Why scale by hot-tier share? Hot tier is the expensive one (full resolution, fast query). Cold or rolled-up tiers cost a fraction. Scaling by hot share keeps the per-tag-year number realistic.
How do I get cost per tag-year? Take last quarter's cloud historian bill, divide by tag count, and annualize. Common cloud historians land at 0.30 to 2.00 dollars per tag-year for hot tier.
Should I include egress? Yes if egress is large. Either fold it into per-tag-year cost or add it to the fixed line. Pick one and be consistent.
How do I model a hybrid (cloud plus on-prem)? Run this calculator for cloud and the data historian storage cost calculator for on-prem. Sum the totals and compare to a pure-cloud or pure-on-prem case.

Last reviewed 2026-05-12.