System Load Calculator
Calculate overall system load combining CPU, I/O wait and runnable process counts.
About System Load Calculator
The three load average figures Linux reports (1, 5 and 15-minute exponentially-weighted moving averages of the run-queue length) each smooth over a different window, so comparing them to each other reveals a trend that no single number shows: 1-min running noticeably higher than 5/15-min signals load is currently rising, while the reverse signals a recent spike subsiding. Weighting them (0.5/0.3/0.2, favoring recency) into one combined figure gives a single trend-aware number for dashboards or alerting thresholds, without discarding the longer-window context entirely.
Formula
Weighted combined load
combined_load = load_1min × 0.5 + load_5min × 0.3 + load_15min × 0.2
- L_1
- 1-minute load average
- L_5
- 5-minute load average
- L_{15}
- 15-minute load average
Worked example
With the default values below, System Load Calculator returns Weighted Combined Load of 4.420. Change any input above and every figure here is recalculated in your browser.
Inputs used
- 1-Minute Load Averageminimum 0
- 5.2
- 5-Minute Load Averageminimum 0
- 4
- 15-Minute Load Averageminimum 0
- 3.1
- CPU Coresminimum 1
- 4
Results
- Weighted Combined Load
- 4.420
- Trend
- Rising — recent load (1-min) is notably higher than the 5/15-minute averages; system load is climbing.
- Combined Load per Core
- 1.105
- Severity
- Overloaded — combined load exceeds available core capacity; expect queuing.
Step by step
- 1Values used
- 2Weighted combined load
- 3Weighted Combined Load= 4.420
- 4Trend= Rising — recent load (1-min) is notably higher than the 5/15-minute averages; system load is climbing.
- 5Combined Load per Core= 1.105
- 6Severity= Overloaded — combined load exceeds available core capacity; expect queuing.
Assumptions and limits
- The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax or compounding frequency into account.
- Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
Why do 1, 5 and 15-minute load averages sometimes disagree so much?
Because they're independently-decaying exponential moving averages, not simple windowed averages — a short, sharp spike shows up strongly in the 1-minute figure almost immediately, but takes much longer to meaningfully move the 15-minute figure, which is exactly what makes comparing them useful for spotting whether load is currently rising or falling.
What does 'load average' actually count on Linux?
It counts the average number of processes in the run queue (runnable, waiting for CPU) plus processes in uninterruptible sleep (typically waiting on disk I/O) — not just CPU-runnable tasks. This is why load average can be high even when CPUs look idle, if many processes are blocked on slow storage.
Is a load average equal to the number of cores 'fully loaded but fine'?
Roughly, yes — load average equal to core count generally means the CPUs are fully utilized with essentially no queuing. Load average significantly above core count indicates tasks are waiting for a turn on the CPU (or for I/O), and load average well below it indicates spare capacity.