What are the thrust-to-weight ratios of the Gripen and F-35?

1. What the numbers in reporting actually represent — thrust, weight, and calculation choices

Different outlets calculate TWR with different inputs: some use dry thrust vs empty weight, some use afterburner thrust vs takeoff weight, and some use “maximum” combinations. The March 2025 technical comparison cites the F135 producing 191 kN with afterburner and 125 kN dry and concludes a maximum F-35A TWR of “around 1.05” based on those figures and an empty weight cited there ^[1]. Other comparisons list engine thrust magnitudes (F-35 ~43,000 lb with reheat; Gripen RM12 ~18,100 lb with reheat) without always stating which aircraft weight was paired with that thrust to derive TWR ^{[2] [3]}.

2. What mainstream compilations report for the F-35

A technical dossier that aggregates available figures states the F-35A’s maximum thrust-to-weight ratio is approximately 1.05, using the F135’s thrust numbers (125 kN dry / 191 kN with afterburner) and an F-35A weight baseline ^[1]. Public spec-comparison pages list the Pratt & Whitney F135 as about 28,000 lb dry and 43,000 lb with reheat—values commonly used by analysts when producing TWR estimates ^[2].

3. What mainstream compilations report for the Gripen

Reporting and analysis pieces give the Gripen’s single-engine thrust in the neighborhood of 18,000–18,100 lb with afterburner for the RM12/derived F404 family and around 12,000 lb dry; several sources explicitly cite that engine output and, in commentary, call Gripen’s TWR lower than heavy twin-engine fighters but point to low drag and low wing loading as compensating factors ^{[3] [4] [2]}. Some blog-style comparisons have produced specific TWR figures (for example, older tables claiming ~1.06 for Gripen), but those depend heavily on the chosen weight basis and are heterogeneous across the web ^{[5] [6]}.

4. How to interpret “around 1.05” for the F-35 and the Gripen’s relative TWR

When a source states the F-35A’s maximum TWR is “around 1.05” it is signaling a roughly balanced fighter-class power-to-weight performance when using a lighter weight baseline (empty or light-fuel states) and full afterburner thrust figures ^[1]. By contrast, single-engine light fighters such as the Gripen typically show lower absolute thrust numbers but achieve strong agility in practice through lower aircraft mass, low wing loading, and aerodynamic efficiency; analysts explicitly caution that raw TWR alone does not fully determine combat agility ^{[4] [3]}.

5. Conflicting figures and why they persist

Conflicting TWR numbers across sites arise because authors pick different thrust (dry vs. wet), different weight figures (empty vs. typical mission vs. maximum takeoff) and sometimes include or omit external loads and fuel. Blog compilations and side‑by‑side spec sites will therefore produce different TWRs — some older comparisons assert F-35 TWRs below 1.0 while others and more recent technical summaries place it above 1.0 using stated engine and empty-weight figures ^{[5] [1] [2]}.

6. What sources do not settle and remaining limitations

Available sources do not provide a single authoritative, consistently calculated TWR for each fighter across all mission conditions; they offer engine thrust values and several weight figures but differ on which pairs to use for “the” TWR ^{[1] [2] [3]}. Where numbers are quoted (e.g., F-35 ~1.05 max TWR, Gripen engine thrust ~18,100 lb), readers should note the calculation choices and that operational loads will lower those theoretical maxima ^{[1] [2] [3]}.

Bottom line: recent technical reporting gives the F-35A a maximum TWR of roughly 1.05 using standard engine and empty-weight figures ^[1], while the Gripen’s single-engine thrust is markedly lower in absolute terms (~18,100 lb with afterburner) and thus typically produces a lower raw TWR depending on the weight used — but Gripen advocates point to low drag and wing loading as partial offsets to raw-thrust differences ^{[2] [3] [4]}.