RAM Latency Calculator
Turn a memory kit’s data rate (MT/s) and CAS latency (CL) into real access latency in nanoseconds so you can compare kits fairly.
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Kit A
Kit B
First-word latency = CL × 2000 ÷ data rate. Lower is better. A higher data rate can offset a higher CL, so compare the nanosecond figure rather than the CL number alone.
What is the RAM Latency Calculator?
This tool converts a memory kit’s advertised data rate and CAS latency into true first-word latency in nanoseconds — the fair way to compare kits with different speeds.
How to use it
- 1Enter the memory data rate in MT/s (e.g. 6000).
- 2Enter the CAS latency (CL) value (e.g. 30).
- 3Read the true latency in nanoseconds.
How it works
The bus clock is half the data rate (DDR transfers twice per cycle). True latency (ns) = CL / (data rate / 2) × 1000 = CL × 2000 / data rate.
DDR5-6000 CL30
Latency = 30 × 2000 / 6000 = 10.0 ns, slightly better than DDR5-6400 CL34 (~10.6 ns).
Limitations & notes
- Only first-word CAS latency is modeled; sub-timings also matter.
- Real workload performance depends on bandwidth, not just latency.
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