Hong Life CalculatorsUnderstanding the IOPS to MB/s calculator — concept and principle
Storage performance is quoted in two ways: IOPS (input/output operations per second) and throughput (megabytes per second). They are linked by the size of each operation, the block size. This calculator converts IOPS and block size into throughput, in both decimal MB/s and binary MiB/s, so you can compare drive specifications, cloud volume limits and benchmark results.
How it is calculated
- Throughput (MB/s) = IOPS × block size (KiB) × 1024 ÷ 1,000,000.
- MiB/s = IOPS × block size (KiB) ÷ 1024.
Block size is entered in KiB (1 KiB = 1024 bytes), as most tools and operating systems report it. MB means 1,000,000 bytes and MiB means 1,048,576 bytes.
The principle
Each operation moves one block. If a device completes 20,000 operations per second and each carries 4 KiB, it moves 20,000 × 4 KiB every second. The two metrics describe different bottlenecks. Small random I/O (4–16 KiB, typical of databases) is limited by how many operations the device can handle, so IOPS is the meaningful figure. Large sequential I/O (128 KiB to 1 MiB, typical of backups and video) is limited by bandwidth, so MB/s matters and IOPS falls. A drive's maximum IOPS and maximum throughput are usually measured at different block sizes, so they cannot both be reached at once.
Worked example
- Inputs: 20,000 IOPS, 4 KiB blocks.
- Bytes per second: 20,000 × 4 × 1024 = 81,920,000.
- Decimal: 81,920,000 ÷ 1,000,000 = 81.92 MB/s.
- Binary: 20,000 × 4 ÷ 1024 = 78.125 MiB/s.
| IOPS | Throughput (MB/s) |
|---|---|
| 5,000 | 20.48 |
| 10,000 | 40.96 |
| 15,000 | 61.44 |
| 20,000 | 81.92 |
| 25,000 | 102.4 |
| 30,000 | 122.88 |
| 40,000 | 163.84 |
How to read the result
Compare the throughput with the limit of the device or link. A SATA interface tops out around 600 MB/s, so 81.92 MB/s at 4 KiB is well within it. Cloud block volumes often cap both IOPS and throughput; your workload hits whichever limit comes first at its block size. If an application needs more throughput, larger I/O sizes usually help more than more IOPS.
Common mistakes
- Mixing MB and MiB; the difference is about 4.9% at this scale and grows with GB and TB.
- Comparing a 4 KiB random IOPS figure with a 128 KiB sequential MB/s figure as if they were the same test.
- Ignoring queue depth; high IOPS ratings often require many outstanding requests.
Frequently asked questions
How many IOPS is 100 MB/s at 4 KiB?
100,000,000 ÷ 4096 ≈ 24,414 IOPS.
Why do tools show different numbers for the same test?
Some report MB/s (decimal) and others MiB/s (binary), and some label MiB/s as MB/s.
Which block size should I use?
Use the size your application actually issues; databases often use 8 or 16 KiB pages, while streaming workloads use much larger blocks.
Sources: IEC 80000-13, Quantities and units — Information science and technology (binary prefixes) · SNIA, Solid State Storage Performance Test Specification (PTS)