Head to head

Gamma IO 18 (1.18) vs Head Hawk 18 (1.20)

They split the measurements 3–3. The widest gap is stiffness, where IO 18 (1.18) is 6 percentile points ahead. Every figure is a testing-machine result at a fixed reference tension.

Measured, side by side

Gamma

IO 18 (1.18)

Polyester · 18 ga

Head

Hawk 18 (1.20)

Polyester · 18 ga

Stiffness lower = softer, kinder on the arm
18956th pct
19462nd pct
Tension loss lower = stays where you strung it
3048th pct
2946th pct
Energy return higher = livelier, more free power
8843rd pct
8846th pct
Spin potential higher = more spin off the string bed
6.485th pct
6.384th pct
Ball bite higher = grabs the ball harder
0.43648th pct
0.44653rd pct
Snapback lower = strings slide and snap back
0.0683rd pct
0.0716th pct

Bars are percentile against all 788 strings, and the marked side is the one that measures better — which is not always the one you want. A firmer bed is worse for your elbow and better for your control, and no measurement knows which of those you came for.

Which one wins, by problem

Each string's standing on the site's rankings, out of every measured string in the database. This is where a comparison stops being arithmetic and starts being a decision.

Swapping between them: what tension?

Bed stiffness is published at one reference tension, so the only honest conversion is to scale it. These are starting points from 52 lb, not prescriptions — the calculator takes your own tension.

Coming from IO 18 (1.18) at 52 lb

String Hawk 18 (1.20) at 50.5 lb 22.9 kg

Coming from Hawk 18 (1.20) at 52 lb

String IO 18 (1.18) at 53.6 lb 24.3 kg

Hybrid: what if you used both?

Estimated, not measured. No hybrid combination has been tested as a bed — these figures are the two strings' own lab measurements weighted by how much of the bed each one actually is. Treat them as a guide to which way a pairing moves, never as lab data.

IO 18 (1.18) mains / Hawk 18 (1.20) crosses

Stiffness58th pct · 1 measured
Tension loss48th pct · 1 measured
Energy return43rd pct · 1 measured
Spin potential84th pct · 1 measured
Ball bite49th pct · 1 measured
Snapback3rd pct · 1 measured

Hawk 18 (1.20) mains / IO 18 (1.18) crosses

Stiffness60th pct · 1 measured
Tension loss47th pct · 1 measured
Energy return45th pct · 1 measured
Spin potential84th pct · 1 measured
Ball bite52nd pct · 1 measured
Snapback5th pct · 1 measured

Open this in the hybrid builder

Which goes dead first?

Estimated from tension loss, which is the only thing the database measures about ageing. This is when the bed stops playing the way you strung it — not when the string breaks.

IO 18 (1.18)

~25 hours of play

Hawk 18 (1.20)

~26 hours of play

Both strings in full

Every published measurement
StringGaugeStiff lb/inLoss %Power %SpinBite COFSnap COF
Gamma IO 18 (1.18) Polyester1818930886.40.4360.068
Head Hawk 18 (1.20) Polyester1819429886.30.4460.071

Add a third string IO 18 (1.18) in full Hawk 18 (1.20) in full