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RAM Latency Calculator

Convert memory timings (CL, tRCD, tRP, tRAS) into true latency in nanoseconds.

MT/s
clk
clk
clk
clk

Timings are in memory clock cycles. True latency in nanoseconds is derived from the data rate.

True Latency

First-word latency (CL)

10.00 ns

Time from a read command to the first bit of data arriving.

I/O bus clock

3000 MHz

Cycle time

0.333 ns

tRCD delay

12.67 ns

tRP delay

12.67 ns

tRAS

26.00 ns

tRC (tRP + tRAS)

38.67 ns

Peak bandwidth per channel48.0 GB/s

Assumes one 64-bit channel. Dual channel doubles this, quad channel quadruples it.

About this tool

The RAM Latency Calculator converts memory timings into true latency in nanoseconds, the only number that lets you compare kits across DDR3, DDR4, and DDR5 on equal footing. Two DDR5 kits can advertise the same MHz but land at very different nanosecond latencies depending on their CL rating — and a fast DDR4 kit can sometimes undercut a sluggish DDR5 one for real-world first-access speed.

Use it when you're shopping for memory and trying to decide between two kits with different speeds and timings, or when you're tuning BIOS and want to see the actual nanosecond payoff of dropping CL 30 to CL 28 at the same frequency. Enter the speed (in MT/s or MHz) and CAS Latency, and the calculator returns true latency for CL, tRCD, tRP, and tRAS in ns.

Formula

True latency (ns) = (timing × 2000) ÷ data rate. The factor of 2,000 is because DDR (Double Data Rate) transfers twice per clock cycle, so a kit labelled DDR5-6000 has an actual 3,000 MHz internal clock and a 0.333 ns cycle time. Multiply the CL by that cycle time to get CAS latency in nanoseconds.

When to use it

Ideal for comparing memory kits with different speed/CL combos before buying, evaluating whether a pricier low-latency kit is actually faster than a cheaper higher-MHz one, or tuning XMP/EXPO profiles manually. Pair with the Data Read Visualizer to see how memory latency compares against L1/L2/L3 cache and NVMe, and the WebGPU Benchmark for end-to-end impact on real workloads.

Popular memory kits

Pre-computed true latency and bandwidth for the DDR4 and DDR5 kits most worth comparing in 2026.

DDR5-6000 CL30
10.0 ns — the Ryzen 7000/9000 sweet spot
View details ➜
DDR5-6400 CL32
10.0 ns — Intel-friendly high-bandwidth pick
View details ➜
DDR5-7200 CL34
9.4 ns — flagship overclocker speeds
View details ➜
DDR4-3600 CL16
8.9 ns — the DDR4 gaming default
View details ➜
DDR5-4800 CL40
16.7 ns — JEDEC stock baseline
View details ➜
DDR5-8000 CL38
9.5 ns — cutting-edge 1DPC tuning
View details ➜

Memory comparisons

Generation-vs-generation breakdowns that put raw timings into real-world context.

DDR4 vs DDR5
The memory generation change that's now mainstream — with real caveats.
Read comparison ➜

Frequently asked questions

What's the true latency of DDR5-6000 CL30?
True latency = (CL × 2000) ÷ speed = (30 × 2000) ÷ 6000 = 10 ns. That's one of the fastest mainstream kits currently shipping; most DDR5-6000 kits at stock JEDEC timings sit closer to 13-14 ns.
How do CL and MHz affect RAM speed?
Data rate (MHz) determines how much bandwidth you get; CL determines how long you wait for the first bit. Higher MHz + lower CL = more throughput plus faster access. A kit with twice the MHz and equal CL halves the true latency in nanoseconds.
Is DDR5-6000 CL30 better than DDR4-3600 CL16?
DDR5-6000 CL30 is 10 ns true latency; DDR4-3600 CL16 is 8.9 ns — DDR4 is actually slightly lower latency on that comparison. But DDR5-6000 has nearly 67% more bandwidth, which matters far more for modern CPUs, especially AMD Ryzen 7000/9000 and Intel 12th-gen+.
What are tRCD, tRP, and tRAS?
Secondary timings. tRCD is the delay to activate a row before accessing a column; tRP is the time to close a row before opening another; tRAS is the minimum time a row must stay open. All three are measured in cycles; converting to ns uses the same formula as CL.
Does faster RAM help gaming?
On AMD Ryzen and modern Intel platforms, yes — especially in CPU-bound 1080p titles where the gap between DDR5-5200 CL40 and DDR5-6400 CL32 can be 10-20 fps. At higher resolutions the GPU becomes the bottleneck and RAM speed matters less.
What is JEDEC vs XMP/EXPO?
JEDEC is the default SPD profile every DIMM boots with — conservative timings guaranteed to work anywhere. XMP (Intel) and EXPO (AMD) are overclocking profiles stored on the DIMM that you enable in BIOS to unlock the speeds printed on the heatspreader.

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