Recently US based Global Firepower has published the Global Firepower Index (GFP) /Military Strength Ranking 2021.
Global Firepower Index is an index of measurement and ranking of military power. The GFP ranking is based on each nation's potential war-making capability across land, sea, and air fought by conventional means. The results incorporate values related to manpower, equipment, natural resources, finances, and geography represented by 50+ individual factors used in formulating the finalized GFP ranks - which provide an interesting glimpse into an increasingly volatile global landscape where war seems all but an inevitability.
India ranked fourth in the Index with 542 combat aircraft, 17 submarines, 4,730 tanks, and 37 attack helicopters. The index is calculated using fifty individual factors such as geography, logistical capability, manpower, land forces, airpower, natural resources, naval forces and financials.