Why fourteen copies if I back up once a day?

Because it counts how many restore points are stored at the same time, not how often backups run. The GFS scheme “seven daily, four weekly, three monthly” keeps fourteen recoverable states on disk at once. That number multiplies the storage requirement—not the schedule.

Is a gigabyte 1000 megabytes or 1024?

Hosting plans and disk packaging use 1000, the decimal system. Operating systems usually show binary units, gibibytes, but label them with the same letters. As a result, a 1 TB disk appears as about 931 GB. The “GB / GiB” switch at the top of the panel converts both the entered values and the result, so you do not need to rewrite anything.

Where do I get compression and deduplication ratios?

Use the report from your storage system: Veeam and most disk arrays show the actual ratio for the period. Until you have that figure, use this guideline: databases, email, and text logs compress at about 2:1; already compressed data—video, images, and archives—does not compress at all. Deduplication has a noticeable effect when there are many identical full copies or similar virtual machines. If you are not sure, leave the values unchanged: the table below the chart still shows all four options.

What does “the disk will fail” mean, and how is it different from “there will not be enough space”?

A disk is considered to have failed not when it is completely full, but when the remaining free space drops below the configured reserve. On such a volume, you can no longer create a snapshot or export a temporary database copy, even though there is technically still space left. That is why the calculator finds the month when used space crosses the threshold and calls it the date.

Why does compression apply to copies but not to the data?

Because the backup storage compresses the copies, not the file system containing the live data. Live files remain as they are; otherwise, you could not work with them directly. If compression is also enabled on the volume itself, enter the used space after compression: the field expects the actual used capacity, not the pre-compression data size.

The copies are stored separately—how should I calculate this?

Use two passes. First, enter zeros in all four storage fields and see what happens to the working volume. Then restore the scheme and enter the size of the backup storage in “disk capacity”: the “Copies use” row is the answer for that storage. The calculation link preserves both versions, so you can compare them in two tabs.

Why does the browser calculate it instead of the server?

Because this is arithmetic involving about fifty rows. None of the entered values are sent anywhere—the page makes no requests after loading, as you can see in the developer tools. The calculation link is built in the address bar by the same script, while CSV export and printing are handled on the device.

Disk and backup space calculation

Storage calculation

Change the numbers on the left—the result, table, and chart update as you type.

How it is calculated

Volume units GB, decimal GiB, binary The toggle also converts values already entered: a 1 TB disk on the plan equals 931 GiB as shown by the system.

Current data stored Data only, without copies: files, databases, email, logs, and uploads. Stored data is a number from zero.

Data growth The difference between two measurements, not a guess. Growth cannot be calculated from a single measurement. Growth is a number from zero.

How growth is specified volume per month % per month % per year Monthly volume produces a straight line. Percentages are based on how much data has accumulated by that month, so the line curves upward.

Calculation horizon How far ahead to calculate. The monthly table and chart cover exactly this period. The horizon is a whole number from 1 to 600 months.

Backup scheme full backups only full plus incremental backups one full backup, then incremental backups With “full plus incremental backups,” daily points are incremental, while weekly, monthly, and yearly points are full backups: this is how a typical schedule with one active full backup per week works.

Daily copies to keep How many of the most recent daily points are stored at the same time. The number of copies is a whole number from 0 to 500.

Weekly copies to keep Usually four—weekly copies for the past month. Number of copies—an integer from 0 to 500.

Monthly copies to keep These restore points are usually what consume the most storage. Number of copies—an integer from 0 to 500.

Annual copies to keep A multi-year archive. Enter zero if you don't need one. Number of copies—an integer from 0 to 500.

Change between copies The share of data that changes between copies. This is the size of the incremental copy. Change must be a number from 0 to 100 percent.

Copy compression 2:1 is typical for databases and text. Use 1:1 for video and archives. Compression must be a number from 1 to 100.

Deduplication Not every storage system supports it. If you're not sure, leave it at 1:1. Deduplication must be a number from 1 to 100.

Capacity of one disk The nominal capacity of one disk or the storage plan size. Disk capacity must be greater than zero.

Disks in array That many identical disks. Without an array, use one. The number of disks must be an integer from 1 to 1000.

Array level No array RAID 1 RAID 5 RAID 6 RAID 10 Without an array, disk capacities are simply added together. A mirror provides the capacity of one disk, RAID 5 loses one disk, RAID 6 loses two, and RAID 10 provides half the total capacity.

Keep free The share of the volume that must remain empty for snapshots, temporary database copies, and logs between cleanups. Reserve must be a number from 0 to 90 percent.

Storage cost Per gigabyte per month under your plan. Enter zero if you own the disk and pay nothing. Cost must be a number of zero or higher.

Currency ₽ RUB $ USD € EUR ₴ UAH

There is no “Calculate” button: the result updates automatically.

Minimum drive size

—GB

Data at end of term —

Restore points —

Backups take up —

Data with backups —

Usable capacity —

Threshold with buffer —

Free space remaining —

Added per month —

The drive will fill up —

Capacity usage at end of term

The blue bar shows data with backups; the black marker shows the threshold below which less than the buffer remains free.

Will take up — threshold —

The browser does the math: no data is sent anywhere. “Calculation link” puts the values in the page URL, so you can share the calculation.

Monthly capacity usage

The line shows how much space is occupied by data and backups by that month. The solid line shows usable capacity; the dashed line shows the threshold below which less than the buffer remains free.

at the end of term — threshold with buffer —

What compression and deduplication do

Backups at the end of term in four scenarios
Scenario	Backups	Including data

Monthly table Collapse monthly table

Month by month
Month	Data	Backups	Total	Available	Until threshold

Calculation inputs Collapse input data

What goes in the fields
Metric	Value

How to use it

In “data currently used,” enter only the data itself, without copies: use the hosting panel, du -sh, or the volume properties. The calculator will calculate the copies from the storage scheme.
Enter growth as the difference between two measurements taken at least a month apart. If the data grows by a percentage, switch the method: percentage growth curves upward, and after three years the difference from linear growth becomes several times larger.
Set the horizon to the period covered by your decision. Use one quarter through the end of the paid period, or three years through the end of the hardware’s service life.
Copy the storage scheme from your backup settings as is: the number of daily, weekly, monthly, and yearly restore points stored at the same time. This is the main multiplier—fourteen points use fourteen times as much space as one full copy.
Enter the compression and deduplication ratios shown in your storage report. If you do not know them, leave them at 1:1 and check the “what compression and deduplication do” table: it shows all four options at once.
If the disks are combined into an array, enter their number and level: the usable capacity of RAID 6 with eight disks is six disks, not eight.
Check the “Disk will fail” row—it shows the month and year. The monthly table below the chart shows how that date was calculated and can be exported to CSV.

The formula and what it includes

Disk = (Data + Copies ÷ (Compression × Deduplication)) ÷ (1 − Reserve ÷ 100), Copies = Full × Data + Incremental × Data × Change ÷ 100

Data — what is stored on the disk at the end of the period: current usage plus growth over all months in the horizon
Full and incremental — the number of restore points under the storage scheme. A full point is the size of all the data; an incremental point is the size of the changed portion
Change — the percentage of data that changes from one copy to the next. At 3%, an incremental copy is three hundredths of a full copy
Compression and deduplication — how many times the storage reduces the size of copies. They apply to copies, not the data itself, and multiply together
Reserve — the share of the volume that must remain free. This is why the calculation divides: to leave 20% free after storing the data, the disk must be 1 ÷ 0.8 times larger
Usable capacity — what is actually available after the array is assembled: RAID 1 provides the capacity of one disk, RAID 5 provides one disk less, RAID 6 provides two disks less, and RAID 10 provides half

Gigabytes are decimal by default: 1 GB = 1000 MB, which is how hosting plans and disk packaging calculate capacity. The switch at the top converts both the fields and the result to binary gibibytes, as shown by the operating system. The “Full plus incremental” scheme counts daily points as incremental, and weekly, monthly, and yearly points as full. The “One full, then incrementals” scheme stores one full snapshot followed by a chain of changes; in practice, long-term points in this scheme are usually synthesized into full copies, so it provides a lower estimate, while “full only” provides an upper estimate.

Example breakdown: a 2 TB disk and a fourteen-point scheme

The input data is the same as the default field values: you can calculate it mentally and confirm that the tool is telling the truth.

Data currently used: 200 GB
Growth: 5 GB per month
Horizon: 12 months
“Full plus incremental” scheme
7 daily, 4 weekly, 3 monthly, 0 yearly
Change between copies: 3%
Compression: 2:1, deduplication: 1:1
Disk: 2000 GB, no array
Keep free: 20%
Price: ₽2 per GB per month

Data after 12 months: 200 + 5 × 12 = 260 GB.
Restore points: 14. Under the selected scheme, the seven daily points are incremental, while the four weekly and three monthly points are full: 7 full and 7 incremental.
Full copies: 7 × 260 = 1820 GB. Incremental copies: 7 × 260 × 3% = 54.6 GB. Total: 1874.6 GB.
Compression at 2:1 cuts this in half: 937.3 GB. Deduplication at 1:1 changes nothing.
Data and copies combined: 260 + 937.3 = 1197.3 GB. A 20% reserve on the volume means the threshold is 1600 GB.

There is enough space: by the end of the year, 1197.3 GB of 2000 GB is used, leaving 803 GB free—in the panel, this appears as 1.2 TB of 2 TB because it automatically converts large values to terabytes. This calculation requires a disk of at least 1497 GB, or 1.5 TB. Growth consumes about 23 GB per month, so the threshold will be crossed in about 29 months. Without compression, the same copies would occupy 1874.6 GB, and the threshold would already be exceeded today.

Frequently asked questions

Why fourteen copies if I back up once a day?

Because it counts how many restore points are stored at the same time, not how often backups run. The GFS scheme “seven daily, four weekly, three monthly” keeps fourteen recoverable states on disk at once. That number multiplies the storage requirement—not the schedule.
Is a gigabyte 1000 megabytes or 1024?

Hosting plans and disk packaging use 1000, the decimal system. Operating systems usually show binary units, gibibytes, but label them with the same letters. As a result, a 1 TB disk appears as about 931 GB. The “GB / GiB” switch at the top of the panel converts both the entered values and the result, so you do not need to rewrite anything.
Where do I get compression and deduplication ratios?

Use the report from your storage system: Veeam and most disk arrays show the actual ratio for the period. Until you have that figure, use this guideline: databases, email, and text logs compress at about 2:1; already compressed data—video, images, and archives—does not compress at all. Deduplication has a noticeable effect when there are many identical full copies or similar virtual machines. If you are not sure, leave the values unchanged: the table below the chart still shows all four options.
What does “the disk will fail” mean, and how is it different from “there will not be enough space”?

A disk is considered to have failed not when it is completely full, but when the remaining free space drops below the configured reserve. On such a volume, you can no longer create a snapshot or export a temporary database copy, even though there is technically still space left. That is why the calculator finds the month when used space crosses the threshold and calls it the date.
Why does compression apply to copies but not to the data?

Because the backup storage compresses the copies, not the file system containing the live data. Live files remain as they are; otherwise, you could not work with them directly. If compression is also enabled on the volume itself, enter the used space after compression: the field expects the actual used capacity, not the pre-compression data size.
The copies are stored separately—how should I calculate this?

Use two passes. First, enter zeros in all four storage fields and see what happens to the working volume. Then restore the scheme and enter the size of the backup storage in “disk capacity”: the “Copies use” row is the answer for that storage. The calculation link preserves both versions, so you can compare them in two tabs.
Why does the browser calculate it instead of the server?

Because this is arithmetic involving about fifty rows. None of the entered values are sent anywhere—the page makes no requests after loading, as you can see in the developer tools. The calculation link is built in the address bar by the same script, while CSV export and printing are handled on the device.