Specializing in computational finance and low-latency system optimization.
Calculating true memory performance goes beyond simple clock speeds. Use this RAM Latency Calculator to find the real-world access time in nanoseconds, allowing you to compare DDR4 vs DDR5 effectively.
RAM Latency Calculator
RAM Latency Calculator Formula
Formula Source: Crucial Technology – Memory Speed vs Latency | Kingston Technology Insights
Variables:
- CAS Latency (CL): The number of clock cycles it takes for the RAM to respond to a command.
- Data Rate (MT/s): The transfers per second (often marketed as MHz). For DDR, this is twice the actual bus clock.
- Absolute Latency (ns): The real-world time in nanoseconds required to access data.
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What is RAM Latency?
RAM latency, specifically CAS (Column Address Strobe) latency, measures the delay between the moment a memory controller tells the RAM to access a specific data column and the moment that data becomes available. While “Speed” (MT/s) tells you how much data can move per second, “Latency” tells you how quickly that movement starts.
In modern computing, the “First Word Latency” is the most accurate indicator of performance. A high-frequency module (e.g., 6000 MT/s) with a high CL might actually be slower in initial response than a lower-frequency module with a very tight CL.
How to Calculate RAM Latency (Example)
- Identify your RAM’s advertised CAS Latency (e.g., CL16).
- Identify the Data Rate in MT/s (e.g., 3200 MT/s).
- Multiply the CL by 2000 (16 × 2000 = 32,000).
- Divide the result by the Data Rate (32,000 ÷ 3200 = 10ns).
- The absolute latency is 10 nanoseconds.