Calculator
Enter sample item values, choose a formula style, and preview a calculated item expression for a Zabbix blog workflow.
Example Data Table
This table shows sample inputs and generated values for common calculated item cases.
| Use Case | Formula Type | Value A | Value B | Value C | Sample Output | Suggested Item Key |
|---|---|---|---|---|---|---|
| Average CPU load | Average | 60 | 70 | 80 | 70% | custom.cpu.avg |
| Disk used percent | Percentage | 350 | 500 | 0 | 70% | custom.disk.used |
| Memory used percent | Used Capacity | 0 | 16000 | 4000 | 75% | custom.memory.used |
| Traffic gap | Difference | 950 | 740 | 0 | 210 Mbps | custom.net.delta |
Formula Used
This calculator uses sample values to estimate a calculated item result. The selected formula controls how source values are combined.
Average = (A + B + C) / 3
Sum = A + B + C
Difference = A - B
Percentage = (A / B) × 100
Used Capacity = ((Total - Available) / Total) × 100
Moving Average = avg(source item, selected time window)
Final Value = (Base Result × Multiplier) + Offset
The generated expression is a planning aid. Always verify host names, item keys, functions, permissions, update intervals, and supported syntax inside your Zabbix version.
How to Use This Calculator
- Enter the host name used in your monitoring setup.
- Add the calculated item name and custom item key.
- Enter source item keys for the values you want to combine.
- Select the formula type that matches your monitoring goal.
- Add realistic sample values from history or trends.
- Set a threshold to classify the result.
- Press the calculate button to view the generated expression.
- Download the result as CSV or PDF for documentation.
Guide to Creating a Calculated Item in Zabbix
What a Calculated Item Does
A calculated item helps you create a new metric from existing item values. It does not collect data directly from an agent. Instead, it reads stored values and applies a formula. This is useful when one raw metric is not enough. You can combine CPU, memory, disk, traffic, or service values.
Why It Matters
Many monitoring decisions need context. A raw memory value may look large. Yet it becomes clearer when compared with total memory. A calculated item can convert that relation into a percentage. Teams can then build cleaner triggers and dashboards. It also reduces manual spreadsheet work.
Planning the Formula
Start with the question you want to answer. Then choose the source items. Check that each source item has valid recent data. Decide if you need the latest value or an average. Short windows react faster. Longer windows reduce noise. The best choice depends on your alert goal.
Building the Item
Create a new item on the target host or template. Select the calculated item type. Add a clear name and a unique key. Paste the formula into the expression field. Set units, update interval, and history retention. Save the item and wait for the first calculation.
Testing the Output
Review latest data after saving. Compare the calculated value with manual math. If the result is wrong, inspect every item key. Also check unsupported items and missing values. Once verified, connect the item to triggers, graphs, and dashboards. Keep notes for future audits.
FAQs
What is a calculated item in Zabbix?
A calculated item is a metric created from other item values. It uses an expression instead of direct collection from an agent, trapper, or external check.
Can I use this calculator for real monitoring?
Yes, use it for planning and documentation. You should still test the generated expression inside your own Zabbix version before production use.
What does the percentage formula mean?
The percentage formula divides one value by another value, then multiplies by 100. It is useful for disk, memory, and capacity ratios.
Why does the calculator ask for sample values?
Sample values help preview the expected result. They also help you confirm whether the expression produces a reasonable monitoring value.
Can I create trigger logic from this result?
Yes. The threshold status can guide trigger planning. Build the final trigger separately after confirming that the calculated item works correctly.
What is the best time window?
Use short windows for fast alerts. Use longer windows for smoother trends. Critical systems often need both fast checks and trend-based checks.
What happens if a source item is unsupported?
The calculated item may fail or return no useful value. Check source item availability, permissions, keys, and recent history before using the formula.
Can I export the result?
Yes. Use the CSV button for spreadsheet records. Use the PDF button for reports, change notes, documentation, and team reviews.