A tennis racket’s stiffness describes how much its frame resists bending during a laboratory test. A higher stiffness reading generally means the tested frame bends less; a lower reading means it bends more. This is often reported as an RA number in manufacturer and retailer specifications.
RA is useful for comparing frames, but it is not a complete measure of power, control, comfort or injury risk. Beam geometry, layup, mass, swingweight, strings, tension, grip, impact location and the player’s technique all affect the result on court.
Tennis Racket Stiffness at a Glance
| Common specialist convention | General description | Typical frame tendency |
|---|---|---|
| 63 or below | Flexible | More frame bending under the test condition |
| 64 to 67 | Medium | Middle ground between flexible and stiff designs |
| 68 or above | Stiff | Less frame bending under the test condition |
These bands are a common retailer convention, not a rule established by tennis’s governing bodies. Brands, laboratories and retailers may group the same number differently, and an individual production sample can vary from the published target.
What Does RA Mean on a Tennis Racket?
RA is the label commonly attached to a frame-stiffness reading produced by racket diagnostic equipment. The frame is supported and loaded in a repeatable way, and the machine reports how strongly it resists bending in that test.
A reading of 70 does not mean that a racket is “70 percent stiff.” RA should be treated as a comparative test value, not a percentage or a universal grade of quality.
The reading also does not show how every part of the frame bends. A racket can use different wall thicknesses, beam shapes and fiber orientations around the hoop and throat. Two models with the same published RA can therefore have noticeably different vibration, stability and response.
Why Published Stiffness Numbers Can Differ
It is common to see one stiffness value on a manufacturer page and another in a retailer’s measured specification. That does not automatically mean either one is wrong.
Differences can have several causes.
- The manufacturer’s target and tolerance for production
- Variation between individual frames
- A strung sample compared with an unstrung sample
- Different machines, fixtures or laboratory procedures
- Differences in sample preparation and measurement repeatability
- A retailer testing one physical example rather than publishing the brand’s nominal figure
- Confusion between generations or similarly named models
Some current manufacturer specifications explicitly publish an RA target with a tolerance of several points. For a purchase comparison, verify the exact model and generation, then use values produced under the same stated conditions whenever possible.
How Stiffness Affects Racket Performance
Power and energy return
A stiffer frame bends less during impact. In simplified mechanical terms, less frame deformation can reduce the energy that is temporarily stored and dissipated in frame bending, which can support a more efficient rebound.
That does not make the highest-RA racket automatically the most powerful. Racket mass, swingweight, head size, stringbed stiffness, swing speed and impact location can have equal or greater practical importance. A light stiff frame may be easy to accelerate, while a heavier flexible frame may deliver substantial effective mass through contact.
The useful conclusion is comparative: when two otherwise similar frames differ mainly in stiffness, the stiffer design is generally expected to provide a crisper, more direct response and somewhat easier pace. Real rackets are rarely identical in every other respect.
Control
Stiffness is often marketed as either a control benefit or a control problem, depending on the product. Neither claim is universally true.
A firmer frame can provide a consistent, direct launch for a player who likes a crisp response. A more flexible frame can give another player confidence to swing fully because the overall response may be less lively. Directional control still depends heavily on swing path, contact quality, stringbed, head size and mass distribution.
Feel and feedback
Higher-stiffness frames are often described as crisp or firm, while lower-stiffness frames are often described as flexible, muted or connected. These are subjective descriptions rather than measurements.
Manufacturers can change perceived feel through layup, beam design, handle construction, foam, flax or other damping systems. Strings and tension also change impact sound and vibration. This is why RA alone cannot predict whether a player will call a racket comfortable, harsh, lively or dead.
Stability
Stability against twisting on an off-center hit is not the same as bending stiffness. A racket’s twistweight, mass distribution, head geometry and contact point matter strongly.
A high RA does not guarantee a stable frame if the racket is very light or has limited mass around the hoop. Conversely, a lower-RA frame with suitable mass distribution can remain stable through contact.
Does a Stiff Racket Cause Tennis Elbow?
No RA threshold proves that a racket will cause tennis elbow, and no flexible racket can promise to prevent it. Arm symptoms are influenced by technique, workload, previous injury, grip size, racket mass, strings, tension, ball impact and individual tolerance.
Laboratory and biomechanics research shows that impact shock and vibration change with frame properties, impact location and grip conditions. Research also indicates that a tighter stringbed can increase some impact loads in tested conditions. These findings support looking at the entire setup rather than diagnosing risk from one specification.
A player with existing elbow, wrist or shoulder pain should not rely on a product label as treatment. Stop if hitting is painful and seek advice from a qualified health professional. For a broader equipment discussion, see Choosing Arm-Friendly Tennis Rackets.
Stiffness Versus Stringbed Stiffness
Frame stiffness and stringbed stiffness are separate measurements.
- Frame stiffness describes resistance to bending in the racket structure.
- Stringbed stiffness describes the combined response of the installed strings, including string material, gauge, pattern, tension, installation and time since stringing.
A flexible frame with a firm polyester stringbed can still produce a demanding overall setup. A stiff frame with a softer string at an appropriate tension may feel more forgiving to some players, but it does not change the frame’s structural RA.
This distinction is important when comparing demonstrations or reviews. If the strings are different, the reader is not isolating frame stiffness.
Stiffness Versus Other Racket Specifications
| Specification | What it describes | What it does not tell you alone |
|---|---|---|
| RA stiffness | Resistance to frame bending in a particular test | Complete comfort, power or injury risk |
| Static weight | Mass of the racket | How difficult it is to swing |
| Swingweight | Resistance to angular acceleration about a test axis | Exact maneuverability for every player |
| Balance | How mass is distributed toward the head or handle | Twist stability or structural stiffness |
| Head size | Area of the stringbed | Guaranteed sweet-spot size or control |
| Beam dimensions | Width and profile of the frame sections | Exact layup or final response |
| String pattern | Number and arrangement of mains and crosses | Actual stringbed stiffness after installation |
For the full interaction among these specifications, use the Ultimate Tennis Racket Buying Guide. Tennis Racket Size Guide: Length, Head Size and Weight covers dimensions and mass in more depth.
Flexible, Medium or Stiff: Which Should You Choose?
Consider a more flexible frame if:
- You prefer a softer or more flexible impact response.
- You supply your own pace with a long swing.
- You are willing to obtain power from swingweight, mass and string setup rather than frame stiffness alone.
- A lower measured stiffness is one part of the comfortable setup you are trying to build.
The limitation is that some flexible frames can feel less direct or less lively, especially when paired with a low-powered stringbed. A flexible competition frame may also be heavy or demanding despite its lower RA.
Consider a medium-stiffness frame if:
- You want a balance between frame flex and a direct response.
- You are still identifying your preferred feel.
- You want a broad starting point before refining strings and tension.
The middle band does not guarantee versatility. Head size, swingweight, pattern and beam design still determine whether the exact model is forgiving or specialized.
Consider a stiffer frame if:
- You value a crisp response and accessible pace.
- You use a compact or moderate swing and want the frame to deform less at impact.
- You have no discomfort with the complete racket and string setup.
The tradeoff is that a stiff frame may transmit a firmer impact response, particularly with a light frame, off-center contact or firm stringbed. Try the exact setup rather than choosing from the RA number alone.
Level-based recommendations are covered separately in our guide to choosing a racket for your skill level. Player level can guide a starting specification, but it does not determine a single correct stiffness.
How to Compare Stiffness Before Buying
Use this sequence to prevent misleading comparisons.
| Step | Comparison check |
|---|---|
| 1 | Confirm the exact model, head size, generation and year. |
| 2 | Record whether the figure is a manufacturer target or an independent measurement. |
| 3 | Check whether the sample was strung or unstrung. |
| 4 | Compare RA values from the same source or test method when possible. |
| 5 | Compare weight, swingweight, balance, beam, head size and string pattern alongside stiffness. |
| 6 | Note the string, gauge and tension used in any demonstration. |
| 7 | If possible, demo the exact model with a sensible stringbed and evaluate comfort over normal tennis strokes. |
Do not reject a frame because two sources differ by one or two points. That small gap may sit within manufacturing and measurement variation and may matter less than a different string or swingweight.
Can Racket Stiffness Be Changed?
The structural stiffness of a finished frame is set mainly by its materials, layup and geometry. Adding an overgrip, dampener or small amount of tuning mass does not convert a stiff frame into a flexible one.
Customization can change weight, balance, swingweight and stability, which may change how the racket feels and performs. It should not be described as changing RA unless the frame itself is physically altered, which is neither a normal nor advisable adjustment. The Tennis Racket Customization Guide covers those separate variables.
Strings are the practical way to change the overall impact response without replacing the frame. A softer string type, different gauge or suitable tension can change stringbed behavior, but no setup can guarantee comfort for every player.
Common Stiffness Myths
“A higher RA always means more power”
It can support a more efficient, direct frame response, but complete racket power also depends on mass, swingweight, head size, strings, swing speed and impact location.
“A low RA racket is always arm-friendly”
Lower frame stiffness can be one useful factor. A firm stringbed, unsuitable weight, poor contact or excessive workload can still make the complete setup uncomfortable.
“A vibration dampener reduces frame stiffness”
A dampener changes string vibration and sound after impact. It does not materially change the frame’s structural bending stiffness.
“Two rackets with the same RA will feel the same”
They may differ in layup, beam, mass distribution, handle system, strings and vibration behavior. The shared number isolates only one measured property.
More misleading specification shortcuts are addressed in Common Tennis Racket Myths.
Final Verdict
RA is a useful comparison number for how strongly a frame resists bending in a particular test. It is not a percentage, a quality score or a reliable stand-alone prediction of power, control, comfort or injury.
Use stiffness to narrow similar frames, then compare mass, swingweight, balance, head size, strings and exact generation. A demo with an appropriate stringbed provides more useful personal evidence than choosing the highest or lowest number on a specification table.
Frequently Asked Questions
Is 70 RA too stiff for a tennis racket?
It falls within the stiff range under a common retailer convention, but “too stiff” depends on the whole setup and the player. Compare the exact frame, stringbed, mass and personal comfort rather than using a universal cutoff.
Is 60 RA flexible?
Yes, it would generally be categorized as flexible under common specialist ranges. That does not reveal the racket’s weight, power, stability or suitability by itself.
Does stringing a racket change its measured RA?
Published strung and unstrung measurements can differ. Always compare figures reported under the same condition and method, and do not assume one value applies identically after string installation.
Do rackets become more flexible with age?
Repeated loading and damage can change a structure, but there is no reliable universal number of hours or years after which every racket loses a set amount of stiffness. Visible cracks, unusual sounds or deformation require inspection rather than an assumed age-based diagnosis.
Does a thicker beam mean a stiffer racket?
A wider beam can support stiffness, but material, wall thickness, cross-section and layup also matter. Beam width alone is not a substitute for a measured specification.
Should a beginner choose a stiff racket?
Some beginner-oriented frames use stiffer, larger and lighter designs for accessible depth, but this is not a universal requirement. The correct choice depends on physical capacity, swing, comfort and coaching needs.