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Buying guideWeighted, hammer action, touch sensitive: what these terms actually mean.
These terms often appear in digital piano descriptions. They describe different things. This guide explains what each one means, how they relate to an acoustic piano, and what to try in person before deciding.
Published 23 October 2026 · 3 minute read · Written for buyers, not for any one instrument
What your fingers actually move.
An acoustic piano uses an action to move a hammer towards the strings when a key is played. Touch depends on the mechanism, balance, friction and adjustment. A model name or cabinet size alone cannot tell you how an individual used piano will feel.
Many digital pianos aim to reproduce aspects of acoustic touch; portable keyboards can have other design priorities. Compare the intended use and the specific mechanism.
A description of physical feel.
An unweighted action can use springs and still resist your finger. A weighted action uses a different balance of moving components or masses to create its intended touch. Neither label alone establishes return speed, quality or whether an instrument suits a particular player.
Weighted and hammer action are overlapping descriptions rather than two cleanly separated categories. Look for the manufacturer’s named action and compare the instrument at quiet and moderate playing levels.
A moving mechanism linked to the keys.
A digital hammer action uses moving components linked to the keys to create aspects of acoustic-like touch. For example, Kawai describes weighted hammers in its Responsive Hammer actions. This does not mean a digital key contains an acoustic hammer that strikes a string.
Different manufacturers build their hammer actions differently. Some use plastic hammers, some use wooden components, and the geometry varies. The result is that two instruments both labelled hammer action can feel noticeably different from each other. The label does not describe every design detail or tell you how the instrument will feel to you.
Heavier at the bottom, lighter at the top.
Graded action usually describes a designed change in physical feel from the lower to the upper register. Makers use different mechanisms and balances, so do not infer the touch of every acoustic or digital piano from one simplified rule.
Not every graded action feels the same. The weight at each end, the rate of change across the keyboard and the overall resistance differ between manufacturers and models. Some players prefer a lighter overall action; others prefer greater resistance. Neither preference is wrong, and neither can be assessed from a specification. Try the instrument.
Volume follows the speed of the keystroke.
Touch sensitivity, also called velocity sensitivity, means the instrument responds to how fast you press the key, not just whether you press it. Press quickly and the sound is louder; press slowly and it is softer. This is what allows a pianist to play expressively, shaping the volume of each note.
On an acoustic piano, touch sensitivity is a physical consequence of the action: a faster keystroke throws the hammer harder at the string. On a digital piano, a sensor measures the speed of the key and tells the sound engine how loud to play the sample. The two processes are unrelated mechanically, but the musical result is similar: the player controls the volume note by note.
Some instruments advertise many levels of velocity sensitivity. The number matters less than how the instrument responds in the range you actually play at. Test whether you can control quiet and moderate passages comfortably rather than choosing on a sensitivity-level count alone.
Check the maker’s description.
Yamaha’s P-515 manual separates touch-sensitivity settings from physical keyboard weight. Kawai’s ES920 action description gives a manufacturer example of graded hammers and counterweights. These are explanatory references, not a statement that Music Companion stocks those digital models.
Specifications do not settle this.
When comparing instruments with different key actions:
- Play quietly. Can you control the volume at the level you will practise at home? An action that only speaks when you press hard is a problem for a student learning to play softly.
- Play repeated notes. How quickly does the key reset? A sluggish return means fast passages are harder to play cleanly.
- Play across the full range. Does the resistance change naturally from bass to treble, or does the whole keyboard feel the same?
- Try the pedals. Sustain, soft and middle pedals interact with the action. Test them on the actual instrument.
- Bring the player. The person who will practise daily is the one whose hands matter.
The piano viewing comparison guide covers a method for comparing pianos side by side. The acoustic vs digital guide covers the broader instrument choice.
Key action, answered.
What does weighted keys mean?
Weighted is a description of physical key feel, often produced using moving masses or a hammer mechanism. Spring-based unweighted actions also have resistance. The mechanism and its adjustment matter more than a label, so compare how the actual instrument responds.
What is the difference between hammer action and weighted keys?
Hammer action is one way of providing a weighted key feel, using a moving mechanism intended to resemble aspects of an acoustic action. The terms overlap. They do not establish identical mechanisms, key mass or touch across models. Check the maker’s description and try the instrument.
Does graded action mean the bass keys are heavier?
Graded action usually describes a designed change in physical feel from the lower to the upper register. Not every graded action feels the same; the difference between brands and models is significant, and the specification alone does not tell you whether you will like the feel.
What is touch sensitivity on a digital piano?
Touch sensitivity means the instrument produces a louder sound when you press a key harder and a softer sound when you press gently. It responds to the speed (velocity) of the key press, not just whether the key is up or down. Some also have adjustable sensitivity levels, but the number of levels is less important than how the instrument feels under your fingers.
Can a digital piano feel like an acoustic?
Some digital pianos with high quality hammer actions come close, but they are not identical. An acoustic piano action involves a complex wooden mechanism, a real hammer striking a string, and a physical escapement that you can feel. A digital action simulates this with varying degrees of success. Try both if you can, and decide what matters most for the player and the room.
Where the rest is set out on this site: Acoustic vs digital → What a beginner needs → Comparing pianos in person → Available pianos → All guides →
Want to feel the difference?
Ask which acoustic pianos are available to compare at the viewing gallery. If you are also considering a digital instrument, compare it separately; no digital stock is promised here.