Telecom engineers work with signal levels spanning an enormous dynamic range, from 20 watts at a macro cell transmitter down to a trillionth of a watt at the receiver. Expressing these values in linear units would require unwieldy numbers with many zeros, making calculations error-prone and comparisons difficult. The decibel scale compresses this vast range into manageable numbers by using logarithms. A decibel is a relative ratio calculated as ten times the base-ten logarithm of the power ratio, while dBm provides an absolute measure by referencing power to one milliwatt, so zero dBm equals exactly one milliwatt of power.