{
  "slug": "backup-storage-retention-cost",
  "title": "Backup Storage & Retention Cost Calculator",
  "heading": "Backup Storage Retention Cost Calculator",
  "category": "financial",
  "url": "https://www.revenuelab.fyi/toolbox/backup-storage-retention-cost",
  "summary": "Project backup storage growth and cost across a retention policy.",
  "description": "Backup cost isn't just the size of one backup — it's the accumulated footprint of every retained copy under your retention policy, and that footprint keeps growing until the oldest backups start aging out. This calculator models a common daily-full-backup pattern with a fixed retention window, computing total storage held at steady state (once the retention window has fully filled) accounting for a compression/dedup ratio, and multiplies by your storage rate for a monthly cost. It also shows storage at day one versus steady state, since teams often budget off the first backup's size and get blindsided once the retention window fills up weeks later. Incremental-forever or differential backup strategies use far less space than full daily backups for the same retention depth, and this tool includes an incremental-ratio input so you can model that pattern too instead of assuming every backup is a full copy.",
  "formula": "Steady-state storage = full backup size × compression factor × (1 + (retention days − 1) × incremental ratio); cost = storage × $/GB-month.",
  "dateModified": "2026-09-30",
  "run_url": "https://www.revenuelab.fyi/api/public/calc?tool=backup-storage-retention-cost",
  "inputs": [
    {
      "id": "fullSizeGb",
      "label": "Full backup size",
      "kind": "number",
      "hint": null,
      "default": 2000,
      "unit": "GB",
      "min": 1,
      "max": null
    },
    {
      "id": "retentionDays",
      "label": "Retention period",
      "kind": "number",
      "hint": null,
      "default": 30,
      "unit": "days",
      "min": 1,
      "max": null
    },
    {
      "id": "compressionRatio",
      "label": "Compression/dedup factor",
      "kind": "number",
      "hint": null,
      "default": 0.5,
      "unit": null,
      "min": 0.05,
      "max": 1
    },
    {
      "id": "incrementalRatio",
      "label": "Daily change rate (incremental size vs full)",
      "kind": "number",
      "hint": null,
      "default": 5,
      "unit": "%",
      "min": 0,
      "max": 100
    },
    {
      "id": "strategy",
      "label": "Backup strategy",
      "kind": "select",
      "hint": null,
      "default": "incremental",
      "options": [
        {
          "value": "full",
          "label": "Full backup every cycle"
        },
        {
          "value": "incremental",
          "label": "One full + daily incrementals"
        }
      ]
    },
    {
      "id": "storageRate",
      "label": "Storage rate",
      "kind": "number",
      "hint": null,
      "default": 0.023,
      "unit": "$/GB-mo",
      "min": 0,
      "max": null
    }
  ],
  "outputs": [
    {
      "id": "monthlyCost",
      "label": "Steady-state monthly cost",
      "format": "currency",
      "hint": null,
      "primary": true
    },
    {
      "id": "steadyStateGb",
      "label": "Steady-state storage held",
      "format": "number",
      "hint": null,
      "primary": false
    },
    {
      "id": "day1Gb",
      "label": "Day-1 storage (before retention fills)",
      "format": "number",
      "hint": null,
      "primary": false
    },
    {
      "id": "annualCost",
      "label": "Annualized cost",
      "format": "currency",
      "hint": null,
      "primary": false
    }
  ],
  "worked_example": {
    "inputs": [
      "Full backup size: 2000 GB",
      "Retention period: 30 days",
      "Compression/dedup factor: 0.5",
      "Daily change rate (incremental size vs full): 5 %",
      "Backup strategy: One full + daily incrementals",
      "Storage rate: 0.023 $/GB-mo"
    ],
    "outputs": [
      "Steady-state monthly cost: $56.35",
      "Steady-state storage held: 2,450",
      "Day-1 storage (before retention fills): 1,000",
      "Annualized cost: $676.20"
    ]
  },
  "how_to": {
    "title": "How to use this",
    "steps": [
      "Enter full backup size (GB).",
      "Enter retention period (days).",
      "Enter compression/dedup factor.",
      "Enter daily change rate (incremental size vs full) (%).",
      "Enter backup strategy.",
      "Enter storage rate ($/GB-mo).",
      "Read your steady-state monthly cost on the right — it updates as you type.",
      "Hit Share to keep the scenario or send it to someone."
    ]
  },
  "scenarios": [
    {
      "name": "Conservative",
      "description": "Lower-end numbers — what if things land soft?",
      "values": {
        "fullSizeGb": 1200,
        "retentionDays": 18,
        "compressionRatio": 0.3,
        "incrementalRatio": 3,
        "strategy": "incremental",
        "storageRate": 0.0138
      }
    },
    {
      "name": "Typical",
      "description": "Defaults — the most common real-world setup.",
      "values": {
        "fullSizeGb": 2000,
        "retentionDays": 30,
        "compressionRatio": 0.5,
        "incrementalRatio": 5,
        "strategy": "incremental",
        "storageRate": 0.023
      }
    },
    {
      "name": "Ambitious",
      "description": "Higher-end numbers — what if things really pop?",
      "values": {
        "fullSizeGb": 3200,
        "retentionDays": 48,
        "compressionRatio": 0.8,
        "incrementalRatio": 8,
        "strategy": "incremental",
        "storageRate": 0.0368
      }
    }
  ],
  "limitations": [
    "Results are estimates before tax, fees, and inflation unless an input explicitly covers them.",
    "Rates are treated as fixed for the whole period — variable-rate products will drift from this projection.",
    "This is educational maths, not financial advice. Check anything contractual with the lender or your accountant."
  ],
  "faq": [
    {
      "q": "Why does full-backup-every-day cost so much more?",
      "a": "A daily full-backup strategy retained for 30 days stores roughly 30x a single compressed backup's size, since every copy is a complete independent snapshot. Switching to one full backup plus daily incrementals captures only the changed data each day — for a database changing 5% per day, 30 days of retention costs closer to 2.5x the full backup size instead of 30x, an order-of-magnitude difference."
    },
    {
      "q": "What compression ratio should I actually assume?",
      "a": "Text-heavy data like databases and logs typically compress to 30-60% of raw size; already-compressed data like images, video, or encrypted volumes barely compresses at all (90-100% of raw size). Check your backup tool's own reporting after the first few cycles rather than guessing, since dedup ratios vary enormously by data type and backup software."
    },
    {
      "q": "Does longer retention always mean proportionally higher cost?",
      "a": "With incremental-forever backups, no — cost grows roughly linearly with retention days but at the (much smaller) daily-change-rate slope, not the full-backup-size slope. Going from 30 to 90 days of retention on an incremental strategy might only add 20-40% to storage cost, while the same extension on a full-daily strategy would triple it."
    }
  ],
  "related": [
    "https://www.revenuelab.fyi/toolbox/rpo-rto-cost-calculator",
    "https://www.revenuelab.fyi/toolbox/s3-storage-tiering-cost",
    "https://www.revenuelab.fyi/toolbox/database-iops-cost"
  ],
  "license": "CC-BY-4.0",
  "citation": "RevenueLab — Backup Storage & Retention Cost Calculator (https://www.revenuelab.fyi/toolbox/backup-storage-retention-cost)"
}