RAM Latency Calculator: Convert CL to Nanoseconds

Got a RAM kit you want to check? Put your CAS latency and speed into the calculator below. You get true latency in nanoseconds, which actually tells you how fast the memory responds. Way more useful than just looking at CL numbers.

What is RAM Latency

Your processor asks memory for data constantly. Memory needs time to respond. This delay is latency, expressed in nanoseconds. Sounds insignificant but your CPU fires off millions of requests per second, so even tiny waits add up.

RAM boxes show specs like CL14, CL16, CL30. Marketing loves these numbers. Problem is, CL by itself tells you almost nothing. CL measures clock cycles. Not time. Same CL16 on 3200 MHz stick and on 2400 MHz stick give totally different real world delays.

True latency solves this. You plug in CL and frequency, get nanoseconds out. Works across DDR4, DDR5, any speed rating.

The Formula Behind the Calculator

True Latency (ns) = (CL x 2000) / Speed

DDR4-3600 CL16: 16 x 2000 / 3600 = 8.89 ns. The 2000 is there because DDR moves data on both clock edges.

DDR5-6000 CL30 seems worse but 30 x 2000 / 6000 = 10 ns. Same as DDR4-3200 CL16.

DDR4 and DDR5 Head to Head

DDR5 specs confuse people. CL36? CL40? Looks awful next to DDR4. But DDR5 operates between 4800 and 8000+ MHz, faster clocks make up for bigger CL values.

Bunch of DDR5 setups end up matching or beating DDR4 latency:

  • DDR4-3200 CL14 — 8.75 ns, B-die
  • DDR4-3600 CL16 — 8.89 ns
  • DDR4-3200 CL16 — 10 ns
  • DDR4-3600 CL18 — 10 ns
  • DDR5-6000 CL30 — 10 ns
  • DDR5-6400 CL32 — 10 ns
  • DDR5-7200 CL34 — 9.44 ns
  • DDR5-4800 CL40 — 16.67 ns

DDR5-7200 CL34 beats most DDR4. DDR5-4800 CL40 loses to budget DDR4.

Does Any of This Affect Gaming

Does latency matter for games? Depends. CPU-limited situations show gains. High refresh competitive shooters, RTS games with tons of units, flight sims. Stuff that hammers the processor.

Faster RAM gets data to your CPU with less waiting. More frames, smoother gameplay in those scenarios.

But here is the thing. At 4K resolution with a beefy graphics card, the GPU usually hits its limit first. Memory latency stops mattering because your framerate is already capped by graphics horsepower. Same goes for most modern AAA titles at high settings. They lean heavily on GPU performance.

Workstation users care about this stuff too. Compiling code, running databases, scientific computing. These workloads constantly shuffle data between CPU and RAM. Faster memory speeds things up noticeably. Video editing benefits more from capacity than speed though. Get 32GB before worrying about latency if you use Premiere or Resolve.

Some rough targets depending on your use case:

  • Esports and competitive gaming: shoot for under 9 ns
  • General gaming at 1080p or 1440p: under 11 ns works great
  • Tight budget builds: anything under 12 ns is perfectly fine
  • Workstation stuff: under 10 ns helps, but get enough capacity first

How to Check What Your Current RAM Is Running

Look at the sticker on your RAM. Model number includes speed and CL rating.

Prefer not opening your PC? Get CPU-Z, free program. Memory tab for speed, SPD tab for timings.

Task Manager shows speed under Performance > Memory but no latency data. For timings you need CPU-Z or BIOS.

Important: enable XMP (Intel) or EXPO (AMD) in BIOS. Most RAM ships with slow default settings.

What to Buy in 2026

DDR4: get DDR4-3600 CL16, 8.89 ns. CL14 kits hit 8.75 ns but cost more.

DDR5: DDR5-6000 CL30 at 10 ns, good bandwidth. DDR5-7200 prices dropped recently.

Avoid DDR5-4800 CL40 at 16.67 ns. Slower than budget DDR4.

Platform tips:

  • Ryzen: DDR4-3600 or DDR5-6000 for Infinity Fabric sync
  • Intel more flexible with frequencies
  • Two sticks always, dual channel doubles bandwidth
  • Matched kits only, random sticks cause issues

Mistakes People Make All the Time

Buying high MHz without checking CL. DDR4-4000 CL20 sounds fast, works out to 10 ns. DDR4-3200 CL14 at lower clock hits 8.75 ns.

Forgetting XMP. Common mistake. Fast RAM runs at slow defaults until you enable XMP in BIOS.

Single stick setup. One 32GB module has half the bandwidth of two 16GB modules. Install in A2 and B2 slots usually.

Mixing mismatched kits. Bought 16GB two years ago, now adding another 16GB from a different brand? Your motherboard will force both kits to run at the slower one’s speed and timings. Sometimes it refuses to boot at all. Buy a matched set if you need more capacity.

FAQ

How do I calculate RAM latency in nanoseconds?

CL x 2000 / MHz. Example: DDR4-3200 CL16 is 16 x 2000 / 3200 = 10 ns.

Is 10 ns latency good enough?

For gaming and work yes. Esports players targeting 240+ fps benefit from sub 9 ns.

Why does DDR5 have such high CAS latency numbers?

DDR5 runs faster clocks. DDR5-6000 CL30 = DDR4-3200 CL16 = 10 ns.

Should I get CL14 or CL16 DDR4?

CL14 gives roughly 12% lower latency, costs extra. Worth it for competitive gaming, otherwise CL16 saves money.

What CAS latency makes sense for DDR5?

CL30-CL36 at 5600-6400 MHz. DDR5-6000 CL30 is 10 ns, DDR5-7200 CL34 is 9.44 ns.

Does lower latency help with video editing?

Slightly. RAM amount matters more, 32GB or 64GB first.

Can I mix RAM sticks with different latencies?

Not recommended, system uses slowest timings.

Speed or latency, which one matters more?

Neither alone. True latency combines both. Always compare the nanosecond result.

How do I turn on XMP in BIOS?

Restart, press Delete or F2 during boot. Look for XMP, DOCP or EXPO option. Enable it, save changes.

Best RAM latency for gaming builds right now?

Sub 9 ns for esports, under 11 ns otherwise. DDR4-3600 CL16, DDR5-6000 CL30.