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All calculatorsMethodology

Memory Timing Calculator

Convert DDR4 or DDR5 MT/s and primary timing labels to nanoseconds, then compare two RAM kits side by side.

Interactive calculator · Method MEMORY_TIMING-1.3 · Last reviewed: 2026-11-04

Compare RAM timing profiles in nanoseconds

Enter the data rate and CL-tRCD-tRP-tRAS values printed for each profile. The result shows cycle time and every primary timing for both kits.

Your inputs

Try an example

Kit A is the memory kit you are considering first. Kit B is optional comparison data, prefilled with a common DDR4 example.

Use the active Kit A profile values from the label, specification sheet, BIOS, XMP, or EXPO screen. Enter the advertised DDR rate in MT/s, not the base clock in MHz.

Kit B is the comparison profile. Replace the defaults with its actual MT/s and CL-tRCD-tRP-tRAS values.

Default worked example. Edit the inputs to calculate your scenario.

Default worked example

Kit A CAS true latency 10 ns
Kit B CAS true latency 8.89 ns
CAS latency difference Kit B is lower by 1.11 ns
Kit A cycle time 0.333 ns
Kit B cycle time 0.556 ns
Kit A tRCD / tRP 12 / 12 ns
Kit B tRCD / tRP 10.56 / 10.56 ns
Kit A tRAS 25.33 ns
Kit B tRAS 21.67 ns

Timing ns = timing cycles × (2000 ÷ MT/s). The CAS difference compares exact converted delays. These timing conversions do not measure complete system latency or overall performance.

How to use the calculator

Compare two DDR memory kits using their entered timings. Enter data rate in MT/s and whole-cycle CAS, tRCD, tRP and tRAS values for each. The calculator converts every row to nanoseconds; it does not certify a supported memory profile.

What the result means

Lower converted CAS delay means less time for that timing component under the entered clocks. It does not establish overall memory or application performance. Tiny nonzero CAS differences remain visible even when the rounded CAS cards look alike.

Formula and units

One DDR clock cycle takes 2000 / MT/s nanoseconds because DDR transfers twice per clock. Each delay is entered timing cycles × that clock duration. The CAS comparison uses exact ratios before display rounding; identical converted delays are an exact tie.

Worked examples

Kit A data rate (MT/s): 6000 MT/s; Kit A CAS latency (CL): 30 cycles: Kit A data rate (MT/s): 6000 MT/s; Kit A CAS latency (CL): 30 cycles; Kit A tRCD: 36 cycles; Kit A tRP: 36 cycles; Kit A tRAS: 76 cycles; Kit B data rate (MT/s): 3600 MT/s; Kit B CAS latency (CL): 16 cycles; Kit B tRCD: 19 cycles; Kit B tRP: 19 cycles; Kit B tRAS: 39 cycles.
Example result: Kit A CAS true latency: 10 ns; Kit B CAS true latency: 8.89 ns; CAS latency difference: Kit B is lower by 1.11 ns; Kit A cycle time: 0.333 ns; Kit B cycle time: 0.556 ns; Kit A tRCD / tRP: 12 / 12 ns; Kit B tRCD / tRP: 10.56 / 10.56 ns; Kit A tRAS: 25.33 ns; Kit B tRAS: 21.67 ns.

Kit A data rate (MT/s): 9000 MT/s; Kit A CAS latency (CL): 45 cycles: Kit A data rate (MT/s): 9000 MT/s; Kit A CAS latency (CL): 45 cycles; Kit A tRCD: 54 cycles; Kit A tRP: 36 cycles; Kit A tRAS: 76 cycles; Kit B data rate (MT/s): 3600 MT/s; Kit B CAS latency (CL): 16 cycles; Kit B tRCD: 19 cycles; Kit B tRP: 19 cycles; Kit B tRAS: 39 cycles.
Example result: Kit A CAS true latency: 10 ns; Kit B CAS true latency: 8.89 ns; CAS latency difference: Kit B is lower by 1.11 ns; Kit A cycle time: 0.222 ns; Kit B cycle time: 0.556 ns; Kit A tRCD / tRP: 12 / 8 ns; Kit B tRCD / tRP: 10.56 / 10.56 ns; Kit A tRAS: 16.89 ns; Kit B tRAS: 21.67 ns.

Limitations and common mistakes

Capacity, transfer bandwidth, memory controller behavior, other timings, training, supported profiles and stability are outside these conversions. The inputs are hypothetical timing counts; no product or platform compatibility is inferred.

Use DDR data rate in MT/s, not its half-rate clock in MHz. Compare the converted CAS duration alongside the other timing rows without treating it as a complete system latency benchmark.

Sources and assumptions

The DDR conversion is a dimensional identity, also described by Kingston. CAS delay is one timing component; these entries do not measure complete system latency, performance, platform support or stability.

Method MEMORY_TIMING-1.3; last formula review 2026-11-04. Sources and their supported claims. Calculation methodology.

Kingston: DDR CAS cycles and nanosecond conversion. This source supports the conversion, not a complete system benchmark.