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RAM Latency Calculator

Convert CL, tRCD, tRP, and tRAS timings into true latency in nanoseconds and compare DDR4 and DDR5 kits side by side.

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.

How to use this tool

  1. Enter the memory data rate

    Type the speed in MT/s as printed on the kit (e.g. DDR5-6000 gets 6000, DDR4-3600 gets 3600). The calculator uses the data rate (not the internal clock), so enter the big number on the box.

  2. Enter the CAS Latency (CL)

    Type the CL timing, typically a small number like 30, 36, or 40 for DDR5 or 16 to 18 for DDR4. CL is the most impactful single timing on first-access latency.

  3. Read the true latency for CL

    The calculator returns true latency in nanoseconds using the formula (CL × 2000) ÷ MT/s. Kits with the same MT/s can land at different ns figures depending on CL, which is the only fair cross-generation comparison.

  4. Compare a second kit side-by-side

    Use Compare mode to enter a second memory kit. The tool compares each timing and peak bandwidth so you can see whether a pricier low-CL kit is actually faster than a cheaper kit with a higher data rate.

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 MT/s 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 data rate. Enter the speed in MT/s 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 labeled 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 kit with a higher data rate, or tuning XMP/EXPO profiles manually. Pair with the Memory & Storage Latency Visualizer to see how memory latency compares against L1/L2/L3 cache and NVMe, and the Power Cost Estimator to weigh running cost across different platform configurations.

Why true latency matters more than MT/s

Memory manufacturers advertise the data rate in MT/s in massive font on the box, but data rate is only half the equation. A kit running at 7200 MT/s might sound faster than a 6000 MT/s kit, but if the 7200 MT/s kit has incredibly loose timings such as CL40, it can take longer to respond to the CPU's initial request for data than a tight 6000 MT/s CL30 kit. In latency-sensitive workloads like high-framerate gaming or large database queries, the time it takes to fetch the first piece of data often impacts performance more than the raw bandwidth available once the transfer starts.

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 ➜

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 ➜
DDR5-6000 CL30 vs DDR5-8000 CL38
The kit that looks slower on paper often wins on AMD — and loses on Intel.
Read comparison ➜
DDR5-6000 CL30 vs DDR5-6400 CL32
Two sweet-spot kits with the same latency and a small bandwidth gap.
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, and DDR5-6000 kits with stock-style timings usually sit around 15-16 ns. For example, CL46 is 15.3 ns and CL48 is 16 ns.
How do CL and MT/s affect RAM speed?
Data rate in MT/s determines how much bandwidth you get, and CL determines how long you wait for the first bit. Higher MT/s plus lower CL means more throughput and faster access. A kit with twice the data rate 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, and tRAS is the minimum time a row must stay open. All three are measured in cycles, and 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, 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.
What is a good RAM latency for gaming?
For a high-end modern gaming PC, a true latency around 10 nanoseconds is considered the sweet spot (e.g., DDR5-6000 CL30 or DDR4-3200 CL16). Anything under 12ns will perform excellently in most titles. As you push below 9ns, the performance returns diminish significantly relative to the cost of the memory kit.
Should I prioritize higher MT/s or lower CL?
Always prioritize reaching your CPU's memory controller sweet spot first. For example, AMD Ryzen 7000 processors perform best around 6000 MT/s because it aligns well with the Infinity Fabric clock. Once you hit that target data rate, spend any remaining budget on getting the lowest CL possible at that speed.

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