Power gain dB calculator

What you send and what you get back

Both magnitudes must use the same physical unit—watts with watts, milliwatts with milliwatts—because the ratio is unitless only when the units match; the calculator does not convert SI prefixes for you. Numeric values and numeric strings are both accepted so form widgets and spreadsheet paste stay convenient. Classic classroom checks include one watt in and two watts out for about three point zero one zero decibels of gain, one hundred milliwatts in and ten milliwatts out for exactly minus ten decibels of loss, and equal powers for zero decibels unity. If you need watts to dBm, voltage gain in dB, or full link-budget arithmetic, treat those as separate tools rather than extending this pure power-gain calculator. Send two finite positive powers under the fields p_in and p_out. Input power is also accepted under the aliases pin, input_power, Pin, or P_in, and output power under pout, output_power, Pout, or P_out, but only one key may appear for each side of the stage. Power must be strictly greater than zero on both ports because G_dB equals ten log ten of P_out over P_in is undefined for non-positive arguments; zero and negative power fail with invalid_input and a message that non-positive power is not allowed. Missing fields, conflicting aliases, NaN, and Infinity fail the same way and are not charged. On success the response includes cleaned p_in and p_out, ratio and linear_gain as P_out over P_in, gain_db and power_gain_db as the same decibel value, attenuation_db as the negated gain so losses read as positive attenuation, kind as gain, loss, or unity, booleans is_gain, is_loss, and is_unity, a short expression string showing the formula with numbers, method power_gain_db, and the formula string G_dB equals ten log ten of P_out over P_in. Pricing for successful API calls is the published base of $0.002 per item; validation failures do not consume prepaid balance.

Where power-gain-in-dB calculations show up in real work

Introductory RF and electronics labs constantly assign amplifier and attenuator drills so students can move between linear power ratios and datasheet decibel figures without mixing formulas. Transmitter and PA teams measure input drive and output power at the same reference plane, convert the ratio to G_dB, and compare it against the small-signal or saturated gain on the data sheet. Cable and filter vendors quote insertion loss as a negative power gain; converting bench meter readings into that figure keeps acceptance tests honest. Optical and microwave metrology reports often mix milliwatts and dB of gain or loss on the same page, so a single trusted closed form prevents sign errors when someone confuses attenuation with gain. Because this capability is a pure parse engine, API pricing is the published base of $0.002 per successful item and failed validation does not consume balance. The browser tool is free for interactive use; scripted API traffic uses prepaid KIT balance at the published rate without hidden per-field surcharges.