RAM Bandwidth Calculator
Theoretical peak memory bandwidth is set by three numbers: how fast the memory transfers data, how wide each channel is, and how many channels run in parallel. Enter the data rate in MT/s (the figure memory is marketed with), the bus width per channel in bits, and the number of channels. This calculator returns the peak bandwidth in megabytes and gigabytes per second, plus the effective clock frequency. It is the upper bound you compare modules against, not a measured benchmark.
Memory bandwidth formula
bus bytes = bus width bits / 8
MB/s = data rate (MT/s) * bus bytes * channels
GB/s = MB/s / 1000
clock MHz = data rate / 2 (for double data rate)
The data rate is in millions of transfers per second, so the product gives megabytes per second directly. DDR clocks at half the data rate because it transfers on both clock edges.
Dual-channel 64-bit bandwidth examples
- DDR4-2400: about 38.4 GB/s.
- DDR4-3200: about 51.2 GB/s.
- DDR5-4800: about 76.8 GB/s.
- DDR5-6000: about 96.0 GB/s.
- Single channel halves these figures; quad channel doubles them.
RAM bandwidth: frequently asked questions
How is memory bandwidth calculated?
Theoretical peak bandwidth is the data transfer rate times the bus width times the number of channels. With the rate in millions of transfers per second (MT/s), a 64-bit (8-byte) channel, and the channel count, the result in megabytes per second is MT/s times 8 times channels. Dividing by 1,000 gives gigabytes per second.
What is the difference between MHz and MT/s?
DDR (double data rate) memory transfers data on both the rising and falling clock edges, so the transfer rate in MT/s is twice the clock frequency in MHz. DDR memory rated at 3,200 MT/s runs on a 1,600 MHz clock. Enter the MT/s figure, which is what memory is usually marketed with.
Why is a standard memory channel 64 bits wide?
A standard DDR memory channel carries 64 data bits (8 bytes) per transfer. Some platforms split this into two 32-bit sub-channels (as in DDR5) but the total data width per channel remains 64 bits for bandwidth purposes. The bus width is a user-editable input so you can match non-standard configurations.
Is theoretical bandwidth the same as real-world bandwidth?
No. Real bandwidth is lower because of refresh cycles, latency, command overhead, and access patterns. Measured bandwidth typically reaches 70 to 90 percent of the theoretical peak. Treat this figure as the upper bound for comparison, not a benchmark result.
Sources and definitions
- Peak bandwidth is data rate times bus width times channel count, a standard definition of memory throughput; double data rate clocks at half the transfer rate.
- National Institute of Standards and Technology: SI prefixes (giga, mega).
Reviewed by the CalculatorHub team, edited by James Graham, 19 June 2026. See our methodology.