When to use this calculator
Recover a linear power ratio from a decibel difference. A negative decibel value represents a power ratio below one.
Explore the ac power & reactance calculators for other questions in this topic. For a related calculation, use the Decibels to Voltage Ratio Calculator: Recover a voltage amplitude ratio from a decibel difference.
PUTTING IT INTO PRACTICE
Decibels to Power Ratio: a worked example
The values below are an illustrative example, not a recommendation. Replace them with measurements or assumptions that match your question.
| Input | Example value |
|---|---|
| Power difference (dB) | 20 |
| Result | 100 × |
- Check the input labels and enter the example values above.
- Apply the relationship: Power ratio = 10^(dB/10).
- The result is 100 ×, rounded for display.
How to interpret your result
A negative decibel value represents a power ratio below one.
Use RMS values in the AC power relationships. Apparent power is measured in VA and real power in watts. Pure-sine conversions and balanced three-phase equations only apply under their stated assumptions.
Frequently asked questions
Why can volt-amps differ from watts?
Apparent power is the RMS voltage-current product, while real power also reflects power factor. They are numerically equal only at a power factor of one.
When is the decibels to power ratio calculator useful?
Recover a linear power ratio from a decibel difference. A negative decibel value represents a power ratio below one.
How do I use the decibels to power ratio calculator?
Enter power difference (db). The result updates automatically. Use the units shown beside each input; the example values illustrate the method.
Which formula does this calculator use?
Power ratio = 10^(dB/10).
What should I check before using the result?
A negative decibel value represents a power ratio below one.
How are results rounded?
Scalar numbers display up to six decimal places, with scientific notation for very large or small values. Text, fraction, date and schedule outputs use the format described on the tool. Intermediate calculations use JavaScript floating-point arithmetic. Keep sensible precision for your measurements.
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