docs: reflect real-world hub cost estimate ranges

[Michael Flanakin (flanakin)]

🛠️ Description

Updates the FinOps hubs cost estimate note to reflect real-world Azure Data Explorer and Microsoft Fabric pricing and calls out that Data Explorer cost varies significantly by region. Addresses the gap reported in #2229 (and previously #1719): the flat $120/$300 baseline understated actual cost for some regions and SKUs.

Fixes #2229

📷 Screenshots

Not applicable — text-only change to an existing note, no visual/UI change.

📋 Checklist

🔬 How did you test this change?

• 🤏 Lint tests
• 🤞 PS -WhatIf / az validate
• 👍 Manually deployed + verified
• 💪 Unit tests
• 🙌 Integration tests

Docs-only change — no build or deploy impact. Lint suite passes (3585/3585, includes the ms.date/frontmatter checks for docs-mslearn).

📦 Deploy to test?

Not applicable — no src/templates changes.

🙋‍♀️ Do any of the following that apply?

• 🚨 This is a breaking change.
• 🤏 The change is less than 20 lines of code.

📑 Did you update docs/changelog.md?

• ✅ Updated changelog (required for dev PRs)
• ➡️ Will add log in a future PR (feature branch PRs only)
• ❎ Log not needed (small/internal change)

📖 Did you update documentation?

• ✅ Public docs in docs (required for dev)
• ✅ Public docs in docs-mslearn (required for dev)
• ✅ Internal dev docs in docs-wiki (required for dev)
• ✅ Internal dev docs in src (required for dev)
• ➡️ Will add docs in a future PR (feature branch PRs only)
• ❎ Docs not needed (small/internal change)

This PR is the doc update — docs-mslearn/toolkit/hubs/finops-hubs-overview.md.

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[Roland Krummenacher (RolandKrummenacher)]

Agreed the old figures were understated — thanks for picking up #2229. Two things before this lands.

This is one of four surfaces carrying these numbers, and the other three still say $120/$300/$5. Notably including the portal deploy UI, which is where most customers actually encounter the estimate:

• src/templates/finops-hub/createUiDefinition.json — line 97 ($120/mo for ADX), line 117 ($300/mo for F2), line 244 (~$5/mo per million), line 289, and the worked example on line 577 ($250/mo). None are in this diff.
• docs-mslearn/toolkit/power-bi/help-me-choose.md:52 — comparison table still reads Starts at $120 + ~$10 per $1M, Starts at $300, and ~$3-5 per $1M.
• docs/deploy/finops-hub-latest.ui.json — generated, so it follows once createUiDefinition.json is updated.

As it stands the docs and the deployment experience would quote different headline costs for the same thing.

The $15 figure contradicts the $10 in the same sentence — inline below.

Also worth confirming the calculator behind https://aka.ms/finops/hubs/calculator was refreshed, since the note sends people there for the detail.

[Roland Krummenacher (RolandKrummenacher)]

These two numbers can't both be right:

...plus $10 in Azure storage and processing cost per $1M being monitored. ... Cost without Data Explorer or Fabric is $15 per $1M.

The old pairing ($10 with Data Explorer, $5 without) was coherent — drop ADX, drop the ingestion-side cost. The new pairing has the no-ADX deployment costing more per $1M than the ADX deployment's incremental, which inverts that. One of the two has been updated and the other hasn't.

If $15 is the corrected storage + Data Factory figure, then the $10 here and in the headline on line 28 both need to move with it. Worth double-checking the number itself too — it's a 3-5x jump from the ~$3-5 per $1M quoted in help-me-choose.md:52.

Nit: dropping "(we estimate ~20GB per $1M)" removes the only handle a reader has for sanity-checking against their own data volume. Could it stay alongside the new "region" caveat rather than being swapped out for it?

[Roland Krummenacher (RolandKrummenacher)]

If the per-$1M figure is being revised (see the note on line 30 — the body now says $15 without Data Explorer while this line and the next still say $10), this headline needs to move in step. Right now a reader gets $10 here, $10 in the first half of the note, and $15 in the second half.

[Roland Krummenacher (RolandKrummenacher)]

Re-reviewed at b4e679e. Since the 2026-08-28 review the branch has picked up a changelog entry, a merge from dev, and two ms.date bot commits — none of the review feedback is addressed yet, so both open threads still stand and I've left them open.

1. The $10 / $15 contradiction is still there. Lines 28 and 30 of finops-hubs-overview.md currently read:

Starts at $160/mo + $10/mo per $1M in cost being monitored.

... plus $10 in Azure storage and processing cost per $1M being monitored. ... Cost without Data Explorer or Fabric is $15 per $1M.

The no-Data-Explorer deployment still comes out more expensive per $1M than the Data Explorer deployment's incremental. Whichever of $10/$15 is correct, the other two occurrences need to move with it.

2. The other three surfaces still carry the old figures. Verified at the PR head:

• src/templates/finops-hub/createUiDefinition.json — L97 $120/mo, L117 $300/mo, L244 ~$5/mo per million, L289 $120/mo + ~$5/mo, L577 worked example $250/mo.
• docs-mslearn/toolkit/power-bi/help-me-choose.md:52 — Starts at $120 + ~$10 per $1M, Starts at $300, ~$3-5 per $1M.
• docs/deploy/finops-hub-latest.ui.json — same five strings (generated; follows once createUiDefinition.json is updated).

The portal deploy UI is where most customers actually see the estimate, so shipping this doc change alone would leave the docs and the deployment experience quoting different headline costs for the same thing.

3. Nit still open: dropping (we estimate ~20GB per $1M) removes the only handle a reader has for sanity-checking against their own data volume. Could it stay alongside the new "region" caveat rather than being swapped for it?

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New since the last review

• The changelog entry itself looks good — right section (FinOps hubs → Changed), correct issue link, sentence casing.
• docs-mslearn/toolkit/changelog.md now conflicts with dev (ms.date and the Changed list — the usual additive pattern). Per AGENTS.md: merge origin/dev in, keep both sides' entries, and set ms.date to the merge date rather than either side's value.
• Still worth confirming the calculator behind https://aka.ms/finops/hubs/calculator was refreshed, since the note sends people there for the detail.