# Compression in Mastering Explained > Mastering compression is not mix compression turned down. The ratio, attack and release ranges that work on a full mix, and how to hear whether it helped. [All guides](/blog) # Compression in Mastering Explained Published 24 August 2026, 03:00 UTC · updated 12 August 2026, 21:30 UTC · by Loopin Mastering compression does one job: making a mix feel like one thing instead of several. One to two decibels of reduction does it, and more than three usually undoes it. ## The numbers that work on a full mix Ratio 1.5:1 to 2:1. Threshold set so the loudest sections show one to two decibels of gain reduction and quiet sections show none. Attack slow — 30 milliseconds or more. Release timed so the meter returns to zero between phrases, usually 100–300 ms or auto. These are much gentler than mix settings for a reason: on a full mix you are moving everything at once, so a 4:1 ratio that flatters a snare will pump the whole record. ## Slow attack, or you lose the transients A fast attack on a master grabs the kick and snare hits before they finish, which is exactly the part that makes a record feel like it has energy. Everything gets rounder and smaller and it is very hard to hear as a problem until you A/B it. Start at 30 ms and go slower if the drums feel soft. The compressor should be responding to the body of the music, not to its edges — that is what separates mastering compression from limiting. ## Release is the setting that causes pumping If the release is shorter than the gaps in the music, the compressor recovers between every beat and you hear the level breathing. If it is much longer, the compressor never lets go and the quiet sections stay squashed. Set it by watching the meter rather than by ear at first: it should return to zero between phrases, not between notes. Then check by ear on a section with space in it, where pumping is most audible. ## It is not for loudness People reach for compression to make a master louder, which is the limiter's job. Compression is for cohesion — making a mix where the elements were tracked separately feel like a performance that happened in a room. If you are asking a compressor for more than three decibels, either the mix balance needs fixing or you actually wanted a limiter. [Trading dynamic range](/blog/what-is-dynamic-range-in-music) at this stage buys you very little that normalisation will not take back. ## How to hear whether it helped Bypass it and match the level — turn the compressed version down by the amount of gain reduction so both are equally loud. Almost every compressor sounds better simply because it is louder, and unmatched A/B is how people talk themselves into settings that hurt. At matched level, ask one question: does the chorus feel bigger than the verse still? If the difference between sections has shrunk, back it off. [Comparing a mastered version against your own attempt](/mastering) at matched level is the fastest way to calibrate what a sensible amount sounds like. ## Frequently asked questions ### How much compression should I use when mastering? One to two decibels of gain reduction on the loudest sections, at a ratio of 1.5:1 to 2:1. Beyond about three decibels you are usually fixing a mix balance problem or reaching for a limiter by mistake. ### What attack and release for a mastering compressor? Attack 30 ms or slower so transients survive; release set so the meter returns to zero between phrases, typically 100-300 ms or auto. A fast attack rounds off the drums and is hard to hear until you A/B it. ### Why does my master pump? The release is shorter than the gaps in the music, so the compressor recovers on every beat. Lengthen it until the meter returns to zero between phrases rather than between notes. ## Related reads - [Master your track free](/mastering) - [The mastering chain explained](/blog/mastering-chain-explained) - [EQ in mastering explained](/blog/eq-in-mastering-explained) --- Source: https://onloopin.com/blog/compression-in-mastering-explained