Technology & Computing
CPU Cache AMAT (Average Memory Access Time) Calculator
Calculate average memory access time from L1 hit time, miss rate and miss penalty, with an optional L2 level.
Your inputs
Change any value to update the result instantly.
AMAT (with L2)
2.5 ns
AMAT without L2 (L1 → memory)
6 ns
Effective L2 miss penalty
30 ns
L1 miss rate
5%
L2 miss rate
20%
Adding an L2 cache reduces effective miss penalty by catching many L1 misses before reaching main memory.
Formula and working
AMAT = L1 hit time + L1 miss rate × L1 miss penalty; with L2: penalty = L2 hit time + L2 miss rate × L2 miss penalty
- 1
Collect the inputs
L1 hit time (ns) = 1 ns; L1 miss rate = 5 %; L2 hit time (ns) = 10 ns; L2 miss rate (of L1 misses) = 20 %; Main memory access time (ns) = 100 ns
- 2
Apply the formula
AMAT = L1 hit time + L1 miss rate × L1 miss penalty; with L2: penalty = L2 hit time + L2 miss rate × L2 miss penalty
- 3
Result
AMAT (with L2) = 2.5 ns
Frequently asked questions
Important limitation
This is an educational estimate based only on the values and formula shown. Verify current rates, rules, units, and professional standards before relying on the result. It is not personalized financial or investment advice.
Report a mistake or request an improvement
Tell us if a formula, unit, explanation, or result needs attention. Your message will include this calculator’s name and page.
Related calculators
CPU MIPS from Clock Speed & IPC Calculator
Calculate CPU throughput in millions of instructions per second (MIPS) from clock speed and instructions per cycle.
PSU Wattage & 80 Plus Efficiency Calculator
Calculate AC power draw from the wall and headroom given a system's DC load and PSU's 80 Plus efficiency tier.
Amdahl's Law Parallel Speedup Calculator
Calculate theoretical maximum speedup from parallelizing part of a workload across multiple processors, per Amdahl's Law.
CAN Bus Baud Rate & Bus Load Calculator
Calculate CAN bus load percentage from baud rate, average frame length and message frequency.
Consistent Hashing Ring Virtual Node Calculator
Estimate key distribution variance across shards on a consistent hashing ring based on virtual nodes per shard.
Database B-Tree Index Fanout & Tree Depth Calculator
Estimate B-tree index fanout and tree depth from page size, key+pointer size and row count.