Memory Latency Calculator

Calculate clock period, CAS latency in nanoseconds, and approximate access latency from DRAM timing parameters.

Live

Input

Data Rate (MT/s)

CAS Latency (CL)

tRCD (cycles)

tRP (cycles)

tRAS (cycles)

Full Random Access

38.57 ns

tRCD + CL + tRP

Row Hit (Read)

12.86 ns

CL only

Parameter	Value
Clock frequency	2800 MHz
Clock period	0.357 ns
CAS latency (CL)	12.86 ns
tRCD	12.86 ns
tRP	12.86 ns
tRAS	18.57 ns
Full access (row miss)	38.57 ns
Row hit access	12.86 ns

Note: These are theoretical DRAM timings. Actual system latency includes controller overhead, bus arbitration, and cache effects (typically 1.5-3x higher).

Example input:

DDR5-5600: CL=36, tRCD=36, tRP=36, tRAS=52 → ~38.5 ns full access

Results

Engineering Notes

Clock Period from Data Rate

For DDR memory, the clock frequency is half the data rate (MT/s ÷ 2). The clock period in nanoseconds = 2000 ÷ dataRate(MT/s). For DDR5-5600: period = 2000/5600 = 0.357 ns.

tRCD, tRP, tRAS Explained

tRCD (RAS-to-CAS Delay): time from ACTIVATE to READ/WRITE command. tRP (Row Precharge): time to close a row and open another. tRAS (Active-to-Precharge): minimum time a row must stay active. All are measured in clock cycles.

This tool is intended for engineering analysis and educational purposes. Values and interpretations should be validated against the applicable JEDEC, PCI-SIG, NVM Express, MIPI, vendor datasheet or other authoritative specification.

Frequently Asked Questions

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