IOPS Calculator | RAID IOPS and Throughput

IOPS calculator for RAID 0, 1, 5, 6 and 10: enter drives, IOPS per disk and read/write mix to get functional IOPS, MB/s and disks for a target. Free.

Also known as: iops calculator · raid iops calculator · raid write penalty calculator · iops to mb/s calculator · storage iops calculator · disk iops calculator · how many disks for iops · ssd vs hdd iops · functional iops formula

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Array and Workload

RAID level

A small write reads data and parity, then writes both: 4 operations.

Number of disks

Minimum 3 for RAID 5. Count data and parity disks, not hot spares.

Drive type

IOPS per disk

8.5 ms seek + 4.17 ms rotational latency

Read percentage

30% writes. About 70 for a general server, 50 for OLTP.

Target IOPS (optional)

Works out how many disks reach it.

Block size

Only changes MB/s. Postgres uses 8 KiB pages, SQL Server 8 KiB pages in 64 KiB extents.

IOPS Result

Functional IOPS, throughput, back-end load and a comparison across RAID levels will appear here.

About IOPS Calculator

An IOPS calculator is used to size a disk array for a database or virtualization host before you buy the drives. Enter a RAID level, a disk count, the IOPS each disk delivers and your read/write mix, and it returns the functional IOPS the array really gives your application after the RAID write penalty, the matching MB/s at your block size, and how many disks a target needs.

Key Features

Applies the RAID write penalty correctly: raw IOPS divided by (read share + write share x penalty), not multiplied
Drive presets for 5,400 and 7,200 RPM SATA, 10K and 15K SAS, SATA SSD and NVMe, or type your own measured figure
Converts IOPS to MB/s and MiB/s at block sizes from 4 KiB to 1 MiB
Works backward from a target IOPS to the number of disks a level needs, including RAID 10's even-disk rule
Shows the back-end disk load so you can see why parity RAID struggles with write-heavy work
Compares functional and 100% write IOPS across RAID 0, 1, 5, 6 and 10 for the same disks

Use Cases

Check whether eight 15K SAS drives in RAID 10 can carry a Postgres server that peaks at 2,000 IOPS
Show a reviewer why a RAID 6 array of 7,200 RPM drives is fine for backups and wrong for a VMware datastore
Estimate how many SSDs a SQL Server instance needs before submitting a hardware request
Turn an IOPS figure into MB/s to compare against a 10 Gbps iSCSI link
Decide between more spinning disks and fewer SSDs for a NAS at a small office in Denver
Sanity-check a storage vendor's quote against the write penalty of the RAID level they proposed

Supported Formats

RAID 0, 1, 5, 6 and 10

HDD presets derived from seek time and RPM, SSD planning figures, or custom IOPS

Block sizes 4 KiB to 1 MiB, output in MB/s and MiB/s

Related Keywords

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raid write penalty calculator

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functional iops formula

How many IOPS does a 7,200 RPM hard drive deliver?

About 80 for small random I/O. A spinning disk serves one random request per seek plus half a revolution, so IOPS is roughly 1000 / (average seek ms + average rotational latency ms), and rotational latency is 30000 / RPM milliseconds. A 7,200 RPM drive has 4.17 ms of rotational latency and around 8.5 ms of seek, which gives about 79 IOPS. A 15K SAS drive gets about 182 from 3.5 ms seek and 2 ms latency. SSDs have no seek at all, which is why they deliver thousands of times more. For your own drives, measure instead of guessing: fio --name=mix --filename=/mnt/test/fio.dat --size=4G --rw=randrw --rwmixread=70 --bs=4k --iodepth=32 --direct=1 --runtime=60 --time_based --group_reporting

Calculated in your browser

All arithmetic runs locally in JavaScript. Nothing about your storage design or hardware is sent anywhere.

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Frequently asked questions

What is IOPS Calculator used for?

IOPS calculator for RAID 0, 1, 5, 6 and 10: enter drives, IOPS per disk and read/write mix to get functional IOPS, MB/s and disks for a target. Free.

Is IOPS Calculator free to use?

Yes. IOPS Calculator is completely free with no usage limits, and there is no paid tier required to use it.

Do I need an account to use IOPS Calculator?

No. IOPS Calculator works immediately in your browser with no signup, login, or email address required.

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