dB Calculator分贝计算器
dB 是火腿日常打交道最多的单位之一。本工具换算 dBm 与瓦特，计算功率比与电压比的分贝值，并把 S 表读数换算为 dBm，便于估算信号强度、馈线损耗和功放增益。
Decibels are part of everyday ham life. Convert between dBm and watts, compute dB values from power or voltage ratios, and translate S-meter readings into dBm, useful for estimating signal strength, feedline loss and amplifier gain.
Convert between dBm, watts, ratios and S-meter readings. Everything runs locally in your browser.dBm、瓦特、比值与 S 表读数互换，所有计算都在本地完成。
dBm / WattsdBm 与瓦特互换
dBm
W
dBm = 10 × log10(power in mW). 0 dBm = 1 mW.0 dBm = 1 毫瓦。
dB Gain / LossdB 增益 / 衰减
dB
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Power: dB = 10·log10(ratio). Voltage: dB = 20·log10(ratio).功率：dB=10·log10(比值)；电压：dB=20·log10(比值)。
S-meter to dBmS 表读数转 dBm
S9
dB
HF convention: S9 = −73 dBm, 6 dB per S-unit, 50 Ω reference.短波惯例：S9 = −73 dBm，每 S 单位 6 dB，50 欧姆基准。
Quick Reference常用速查
| dB | Power ratio 功率比 | Voltage ratio 电压比 |
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