Classical guitar strings come in tensions from light to extra-hard, and a full hard-tension set pulls roughly 88 to 92 pounds on a 650 mm scale guitar, versus about 83 to 86 pounds for normal tension, per D'Addario's published tension charts for its Pro-Arté line. Higher tension means firmer feel, more headroom before buzzing, and more demand on your left hand; lower tension means comfort at the cost of volume and clean attack when you play hard. Most players land best on normal or hard tension, and the right answer is knowable from your guitar, your attack, and your hands.
What does tension actually measure?
Tension is the force each string exerts on the top when tuned to pitch, listed in pounds or kilograms per string and as a set total. It is fixed by three things: the string's mass per length, its scale length, and the pitch you tune it to. Change any one and the tension changes — the same set feels firmer on a 664 mm scale guitar than on a 650 mm one, because the longer vibrating length at equal pitch pulls harder. That is why makers publish tension figures at a stated scale length, usually 650 mm.
One caution before the numbers seduce you: tension and stiffness are not the same thing. A string can measure high in tension yet feel supple if its core and windings are flexible. The charts are a shopping tool, not a substitute for a week of playing on a set.
How do light, normal, hard, and extra-hard differ?
The categories step up roughly two to four pounds per set. Light tension (sometimes labeled moderate) suits players with a light attack, smaller hands, or vintage instruments with fragile bracing. Normal tension is the maker's default assumption and the safest first choice for a student instrument. Hard tension adds firmness for strong right hands and players who want the string to stay in place under aggressive rest stroke. Extra-hard tension exists mostly for loud modern concert instruments and players chasing maximum projection.
| Tension label | Typical set total (650 mm) | Best suited to |
|---|---|---|
| Light / moderate | ~79-83 lb | Light attack, vintage guitars, comfort |
| Normal | ~83-86 lb | Most players, student and concert guitars |
| Hard | ~88-92 lb | Strong right hand, louder modern builds |
| Extra-hard | ~92-95 lb | Powerful concert instruments, projection seekers |
The bands overlap because brands calibrate differently — one maker's hard is another's normal. Savarez, D'Addario, Hannabach, and Augustine all publish per-string figures, and comparing those charts, rather than the labels, is how you translate between brands.
Related stories: Classical or Steel-String: How to Choose · What Is a Torres Guitar?.
How does tension change your guitar's setup?
Higher tension presses the top and neck harder, which can raise action slightly and increase relief on sensitive instruments; lower tension can let the strings sit close enough to buzz when you dig in. If your guitar is set up for normal tension and you drop to light, expect to check the string height at the twelfth fret; if you jump to extra-hard, watch for a stiffening feel rather than a geometry change, which is more common. None of this requires a new setup for a one-step change — it requires a check.
Two cautions from the makers' own documentation. First, very light tension on a modern concert classical can sound underdriven — the top was voiced expecting more force. Second, mixing tensions within a set (hard trebles over normal basses, or the reverse) is common practice among advanced players and is safe; string makers sell mixed sets for exactly this purpose.
Does higher tension make you louder?
Only up to a point, and less than players hope. Loudness comes mostly from the guitar's top, its bracing, and your right-hand technique; tension determines how much force the string transmits per stroke and how much energy the string stores. Extra-hard strings on a quiet guitar yield a firmer feel and somewhat more punch, but they cannot turn a student instrument into a concert guitar — and per the makers' own notes, they accelerate fret wear and fatigue the left hand. A rest-stroke upgrade is cheaper than a string-tension experiment cycle.
Which tension should you buy first?
On the supplied evidence — the published tension charts and makers' usage notes — start with normal tension on any modern classical, and move to hard if you buzz when playing at full volume or if the strings feel vague under a strong thumb. Move toward light only for a specific reason: hand discomfort, a fragile vintage instrument, or a deliberately soft attack. Change one step at a time and live with a set for two weeks; string changes are cheap, but conclusions drawn from one evening of playing are usually wrong.
What the sources do not establish: no supplied published test measures perceived loudness across tensions on matched instruments, and set totals vary by a pound or two between production runs. Treat the table's ranges as honest approximations, per the makers' charts as of March 2026.