Calculator Methodology
Redux ROT Impact Score — transparent, citable, versioned.
This document explains every number the calculator produces: the formulas, the benchmarks behind the defaults, the assumptions we make, and what the model deliberately excludes. It is designed to be shared with analysts, executives, and procurement teams evaluating the results.
01How Every Number Is Computed
Step 1 — Total Data Estate
The calculator sums storage volumes across three environments: on-premises (primary SAN/NAS + archive/tape, excluding backup infrastructure), public cloud (hot, cool, and archive tiers across AWS, Azure, GCP, and OCI), and Microsoft 365 / SaaS (mailbox, OneDrive, SharePoint, Teams, other SaaS). M365 volumes are derived from user count × per-user averages you supply.
Step 2 — Annual Storage Cost
Each environment uses tiered cost-per-TB rates:
- On-prem primary: default $3,000/TB/yr (SAN/NAS fully loaded: controllers, networking, power, floor space, admin)
- On-prem backup: default $600/TB/yr (purpose-built backup appliance), divided by your deduplication ratio
- On-prem archive: default $80/TB/yr (LTO-9 tape or cold object)
- Cloud: live per-region pricing from published AWS, Azure, GCP, OCI rate cards ($/GB/month × 1,024 × 12 = $/TB/yr)
- M365: the higher of (a) mailbox storage at Exchange add-on rate ($0.20/GB/mo) + non-mail license share, or (b) total license cost × 40% storage attribution ratio
cloudCost = Σ provider (hotTB × hotRate + coolTB × coolRate + archiveTB × archiveRate)
m365Cost = max(mailboxStorageCost + nonMailStorageCost, totalLicenseCost × 0.40)
Step 3 — ROT Percentage Estimation
Tier names follow the percentile convention introduced in Methodology v1.0.1 (May 2026).
We compute three estimate tiers — Industry P25 (29%), Industry P50 (45%), and Industry P75 (58%) — then adjust each based on two factors:
- Hygiene adjustment: up to ±10 pp based on your classification maturity, lifecycle policies, duplication rate, stale-data %, and temp-file %.
- Industry retention floor: the fraction of data that is legally non-deletable (e.g., Healthcare 25%, Financial Services 30%, Government 35%). This floor is subtracted from the base ROT %, ensuring regulated industries show lower recoverable ROT.
rotPct = clamp(adjustedROT, 10%, 80%)
Within the total ROT, we split into Redundant (30–40%), Obsolete (35–40%), and Trivial (25–30%) using tier-specific ratios derived from industry literature.
Step 4 — ROT Cost Attribution
Each environment's ROT cost is proportional to its volume share of the total estate. This prevents small environments from absorbing disproportionate cost.
Step 5 — Backup Amplification
On-premises backup infrastructure amplifies ROT cost: every redundant file that lives on primary also exists across your backup copies, reduced only by deduplication.
backupROTTB = onPremROTSlice × backupCopies / dedupRatio
backupAmplificationCost = backupROTTB × $600/TB/yr
Cloud and M365 manage their own backup/versioning and are not amplified through on-prem backup infrastructure.
Step 6 — FinOps Cloud Cost Modeling
For each active cloud provider, we compute a detailed FinOps breakdown:
- Savings Plans: blended rate = covered % × (1 − discount %) + uncovered %. Default: 30% coverage, 30% discount.
- Egress cost: monthly egress TB × per-GB rate × 12, with free-allowance offsets (e.g., OCI 10 TB/mo free).
- Early-deletion penalty: pro-rated penalty if archive-tier ROT is younger than the minimum storage duration (e.g., S3 Glacier 90-day, Azure Archive 180-day).
- Retrieval cost: estimated cost to read archive ROT for classification/deletion, using the provider's highest deep-tier retrieval fee.
Step 7 — Multi-Year Projection
The total annual waste is compounded by your stated annual data growth rate to produce 3-year and 5-year projections.
Quick Wins
The calculator identifies up to 7 non-overlapping remediation opportunities. Each quick win claims an explicit TB slice from the total ROT pool. A running total ensures no TB is double-counted and total savings never exceed annual waste.
02Benchmark Sources
Every external number used in the calculator is cited below with publication year and link. We refresh these annually.
| Benchmark | Value Used | Source | Year |
|---|---|---|---|
| Average breach cost | $4.44 M (global avg) | IBM Cost of a Data Breach Report 2025 | 2025 |
| Enterprise ROT % | 33% of stored data is ROT | Komprise 2025 State of Unstructured Data Management Report (corroborated by Veritas Databerg) | 2025 |
| Dark / ROT data % | 58% of unstructured data is dark or ROT | Exonar Dark Data Research | 2024 |
| Fully-loaded storage cost | $3,300/TB/yr (enterprise average) | Gartner I&O Cost Optimization Survey 2025 | 2025 |
| Productivity waste from ROT | $5.7 M/yr (large enterprise, searching through ROT) | IDC Data Intelligence Report | 2024 |
| Enterprise data spend on ROT | $34 M/yr (large enterprise) | Securiti Data Intelligence Report | 2024 |
| ROT midpoint (Valora) | 40–50% of enterprise data is ROT | Valora Data Waste Research | 2024 |
| Unstructured data share | 80% of enterprise data is unstructured | Komprise 2025 / IDC | 2025 |
| Cloud storage pricing | Per-region, per-tier (hot/cool/archive) | Published rate cards: AWS S3, Azure Blob, GCP, OCI | 2025–26 |
| M365 storage attribution | 40% of per-user license cost | Gartner "Microsoft 365 License Optimization" (2025) + Microsoft 365 E3/E5 SKU pricing analysis | 2025 |
| Exchange Online add-on storage | $0.20/GB/month ($2,458/TB/yr) | Microsoft 365 Admin Center — Exchange Online Plan 2 additional storage pricing | 2025–26 |
03Assumption Table
Every default value the calculator ships with is listed below, along with the rationale and its sensitivity — how much the final annual-waste figure moves if you change the default.
| Parameter | Default | Why This Default | Sensitivity |
|---|---|---|---|
| Data growth rate | 25%/yr | IDC Global DataSphere midpoint for enterprise data growth | High — 5-year projection scales exponentially; ±5 pp shifts 5-yr cost ~18% |
| On-prem primary $/TB/yr | $3,000 | 2026 fully-loaded SAN/NAS (controllers, networking, power, floor space, admin FTE) | High — directly scales on-prem ROT cost; ±$500 shifts annual waste ~8–12% |
| On-prem backup $/TB/yr | $600 | Purpose-built backup appliance (e.g., Dell PowerProtect, Cohesity) | Medium — affects backup amplification cost |
| On-prem archive $/TB/yr | $80 | LTO-9 tape or cold object storage (media + library + admin) | Low — archive is already cheap; moving ±$40 has minimal overall impact |
| Backup copies | 3 | 3-2-1 backup rule (3 copies, 2 media types, 1 offsite) | High — each additional copy linearly increases backup amplification |
| Dedup ratio | 2:1 | Conservative default; many orgs without inline dedup achieve 1:1–2:1 | Medium — higher ratios reduce backup amplification cost proportionally |
| M365 license cost/user/mo | $22 | Blended E3/E5 midpoint ($36 E3 list, weighted by common E3-heavy deployments) | Medium — scales M365 storage attribution (40% of total license) |
| M365 storage attribution ratio | 40% | Gartner 2025 analysis: storage infrastructure = 35–45% of M365 per-user cost | Medium — ±10 pp shifts M365 ROT cost ~25% |
| Avg mailbox size | 5 GB | Typical enterprise with basic retention; ranges 2–25 GB | Low — small per-user; matters at scale (10k+ users) |
| Avg OneDrive/user | 15 GB | Midpoint of observed enterprise usage (quota often 1 TB, actual 5–50 GB) | Low — similar scale effect as mailbox |
| % data untouched 12+ months | 60% | Komprise 2025: 74% of orgs manage 5+ PB; majority untouched. Veritas Data Genomics: 40%+ untouched 3+ years | High — primary driver of hygiene adjustment (±3 pp ROT) |
| Known duplication rate | 30% | Enterprise average for unmanaged file shares (range 20–60%) | Medium — above 40% adds +3 pp to hygiene adjustment |
| Temp/personal files | 12% | Veritas Databerg: avg 26.5% store personal files; 12% is the mid-range for enterprises with BYOD policies | Low — above 20% adds +2 pp to hygiene adjustment |
| Savings Plan coverage | 30% | Typical enterprise starting FinOps maturity; range 0–80% | Low — only affects FinOps breakdown, not headline ROT cost |
| Savings Plan discount | 30% | AWS/Azure typically 20–40% for 1-year commitments | Low — only affects FinOps breakdown |
| Archive data age | 180 days | Beyond most early-deletion minimums (90–180 days), so penalties are usually zero | Low — only triggers penalty if below provider's minimum |
Industry Retention Floors
These floors represent the fraction of data that is legally non-deletable in each industry. They reduce the recoverable ROT ceiling.
| Industry | Floor | Regulatory Basis |
|---|---|---|
| Government | 35% | NARA, FOIA, state sunshine laws |
| Financial Services | 30% | SEC Rule 17a-4, SOX, MiFID II |
| Healthcare | 25% | HIPAA (7-year medical records) |
| Energy | 20% | NERC CIP, EPA record-keeping |
| Manufacturing | 15% | ISO 9001 quality records, OSHA |
| Education | 15% | FERPA student records |
| Retail | 10% | PCI DSS (limited retention) |
| Technology | 10% | Minimal regulatory burden |
| Media & Entertainment | 10% | Minimal regulatory burden |
| Other / Unregulated | 10% | General business record-keeping |
04What We Don't Model
Honesty about model boundaries is essential for credibility. The following costs and effects are deliberately excluded from the calculator.
Egress Costs on ROT Deletion
The FinOps panel shows your current egress spend, but we do not model the one-time egress cost of migrating or deleting ROT across regions. The actual cost depends on whether data is deleted in-place (zero egress) or migrated before deletion.
Reserved Instances & Committed Use Discounts (Compute)
Our savings-plan modeling covers storage commitments only. Compute-attached storage (e.g., EBS volumes on reserved EC2 instances) is not broken out separately. If your ROT lives on compute-attached volumes, the true savings from deletion may be lower than shown.
Scope 3 Carbon Emissions
Storing ROT data consumes energy — powering disks, cooling data centers, manufacturing replacement drives. We do not quantify the CO₂ impact. Estimates range from 2–7 kg CO₂/TB/year for cloud and 10–30 kg CO₂/TB/year for on-prem, but methodology varies widely.
Indirect Productivity Loss
IDC estimates $5.7M/year in large enterprises lost to searching through ROT data. We show this as a benchmark but do not incorporate it into the annual waste figure because the productivity impact varies dramatically by organisation and is difficult to attribute directly to storage costs.
Compliance Fine Exposure
The dashboard shows potential GDPR, CCPA, and HIPAA fine ranges as context, but these are not summed into the headline cost. Fine risk depends on breach probability, data sensitivity, and regulatory jurisdiction — factors outside this model's scope.
Data-in-Transit & Network Costs
Replication traffic, cross-region sync, and VPN/Direct Connect costs associated with ROT data are not modeled. These are highly architecture-dependent.
Software Licensing for Data Management Tools
The cost of classification, DLP, backup, and archival software licenses is not included. We model infrastructure cost, not the tools used to manage it.
Human Cost of Remediation
Cleaning up ROT requires project management, change management, and engineering time. This implementation cost is not deducted from the projected savings shown in Quick Wins.
05Changelog
We use semantic versioning. Major = new calculation model, Minor = new data source or input field, Patch = bug fix or cosmetic.
- •Corrected the v1.0.1 rename: “ROT Impact Score” is now used for an individual user's score (the 0-100 hero metric). “ROT Impact Benchmark” is reserved for the quarterly published aggregate report. This split makes the brand match what the methodology actually computes per user vs. what gets published quarterly.
- •Removed “Conservative / Moderate / Aggressive” tier labels in favor of “Industry P25 / P50 / P75” as the sole tier framing. The percentile labels are honest to the methodology; the qualitative labels implied a risk-judgment the math doesn't make.
- •Updated homepage and OG metadata to lead with the “Redux — ROT Impact Score” brand.
- •Renamed tier labels: Conservative/Moderate/Aggressive → Industry P25/P50/P75.
- •Renamed "Data Trust Index" → "ROT Impact Benchmark" across all user-facing text.
- •Synced all 9 non-English locale files with 33 missing translation keys.
- •Initial public release of the methodology document.
- •7-step calculation pipeline: estate inventory → cost → ROT % → attribution → backup amplification → FinOps → projection.
- •3 estimate tiers: Industry P25 (29%), Industry P50 (45%), Industry P75 (58%).
- •Industry-aware retention floors for 10 industries (Healthcare through Other).
- •Tiered on-prem costing: $3,000 / $600 / $80 per TB/yr (primary / backup / archive).
- •FinOps cloud modeling: savings plans, egress, early-deletion penalties, retrieval costs.
- •M365 cost model: Exchange add-on pricing ($0.20/GB/mo) + 40% storage license attribution (Gartner 2025).
- •Benchmarks updated: IBM 2025 ($4.44M breach), Komprise 2025 (unstructured data), Gartner 2025 ($3,300/TB), IDC 2024, Securiti 2024.
- •Replaced 2015 Veritas Databerg figure with 2024/2025 multi-source corroboration (Komprise, Exonar, Valora).
- •Non-overlapping Quick Wins engine with explicit TB-slice claiming and savings cap.
Questions about the methodology? [email protected]
Last updated May 2026 · Methodology v1.0.2