Electrical and Engineering
RAM Latency Calculator
RAM Latency Calculator calculate true CAS latency, memory clock period, and an estimated first-row access time from DDR data rate and timing values.
Electrical and Engineering
RAM Latency Calculator
Calculate true CAS latency, memory clock period, and an estimated first-row access time from DDR data rate and timing values.
Formula
CAS latency (ns) = CL x 2000 / data rate (MT/s); first-row access (ns) = (tRCD + CL + tRP) x 2000 / data rate.
About the RAM Latency Calculator
Calculate true CAS latency, memory clock period, and an estimated first-row access time from DDR data rate and timing values. This tool keeps the requested measurements separate and applies the named method instead of substituting an unrelated general estimate.
How the RAM Latency Calculator Works
Double-data-rate transfers are converted to the underlying clock period, then timing-cycle counts are multiplied by that period.
Formula
CAS latency (ns) = CL x 2000 / data rate (MT/s); first-row access (ns) = (tRCD + CL + tRP) x 2000 / data rate.
The calculation runs in your browser. Values are validated for required ranges, compatible units, and method-specific restrictions before results are displayed.
Required Inputs
- DDR data rate (required) - enter in MT/s.
- CAS latency (CL) (required) - enter in cycles.
- RAS-to-CAS delay (tRCD) (required) - enter in cycles.
- Row precharge time (tRP) (required) - enter in cycles.
Results Reported
The result panel reports the final answer and the intermediate quantities needed to check the calculation:
- Underlying memory clock (MHz)
- Memory clock period (ns)
- True CAS latency (ns)
- Estimated first-row access (ns)
RAM Latency Calculator Example
Select Example Data in the calculator to load this reproducible input set:
| Input | Example value |
|---|---|
| DDR data rate | 6000 MT/s |
| CAS latency (CL) | 30 cycles |
| RAS-to-CAS delay (tRCD) | 38 cycles |
| Row precharge time (tRP) | 38 cycles |
How to Use the Calculator
- Confirm that the calculator title and formula match the quantity you need.
- Enter every required value using the unit shown with its field.
- Select Example Data to inspect a valid input set, or enter your own values and select Calculate.
- Review all reported values and the displayed formula before using the answer.
- Use Copy Result or Download CSV when you need a reusable record.
Accuracy and Limitations
The first-row estimate is a simplified timing sum. Controller behavior, command rate, bank state, refresh, subtimings, and platform architecture affect observed latency.
Keep units consistent, use measurements that represent the actual situation, retain full precision during the calculation, and round only the final answer. Professional decisions may require current official rules, field measurements, laboratory methods, or specialist review.
Frequently Asked Questions
What does the RAM Latency Calculator calculate?
Calculate true CAS latency, memory clock period, and an estimated first-row access time from DDR data rate and timing values.
Which formula does the RAM Latency Calculator use?
CAS latency (ns) = CL x 2000 / data rate (MT/s); first-row access (ns) = (tRCD + CL + tRP) x 2000 / data rate. Double-data-rate transfers are converted to the underlying clock period, then timing-cycle counts are multiplied by that period.
How should I use the RAM Latency Calculator result?
The first-row estimate is a simplified timing sum. Controller behavior, command rate, bank state, refresh, subtimings, and platform architecture affect observed latency.