RAM Latency Calculator
Enter your memory speed and CAS latency to calculate the true first-word latency in nanoseconds. Lower latency means the memory can begin returning requested data sooner.
Calculate your RAM latency
Enter the two specifications shown on your RAM kit or product page
Use the advertised effective speed, such as 3200, 3600 or 6000 MT/s, and the first timing number shown after CL.
Your result
True latency, cycle time and an easy-to-read breakdown
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The speed and CAS latency are combined, so two kits with different specifications can still produce the same true latency.
True latency is useful for comparing responsiveness, but total RAM performance also depends on bandwidth, timings, capacity and the platform.
How the calculation works
The full formula with a simple worked example
Example: DDR5-6000 CL30 → (30 × 2000) ÷ 6000 = 10 ns
Memory speed
Higher data rates transfer more information each second and reduce the duration of an individual memory clock cycle.
CAS latency
CAS latency counts how many memory clock cycles pass before the requested column data begins to return.
Nanoseconds
Converting the two advertised specifications into time makes different RAM kits easier to compare directly.
Frequently asked questions
What the number means and how to use it
Is lower RAM latency always better?
Lower true latency is generally better for responsiveness, but it is not the only memory-performance factor. Frequency, secondary timings, capacity, channel configuration and the CPU’s memory controller also affect real application and gaming performance.
Why can DDR4-3200 CL16 and DDR4-3600 CL18 both equal 10 ns?
The faster 3600 MT/s kit uses more CAS cycles, while the 3200 MT/s kit uses fewer but longer cycles. When both values are converted to time, the first-word latency is the same.
Should I enter MHz or MT/s?
Enter the advertised DDR number shown on the kit, such as 3200 or 6000. Manufacturers often label this as MHz, but it represents the effective transfer rate in MT/s.
Does this calculator include every RAM timing?
No. It calculates first-word CAS latency using speed and CL. Other timings such as tRCD, tRP and tRAS influence memory behavior but are not part of this specific calculation.
More tools & quick reference
Related calculators and what you need to run your own calculation
DDR4-3200 CL16 and DDR5-6000 CL30 both calculate to 10 ns, even though their bandwidth and platform characteristics are very different.
Memory speed: the advertised number, such as 3600 or 6000.
CAS latency: the CL value or first timing number.