It's more difficult to weigh up the strength of modern militaries than you might think. Our infographic parade ground brings together the 30 countries with the most soldiers for a comparison of military might. China easily takes an unsurprising first place with 2.2 million active troops versus just under 1.5 million US soldiers. But are India (1.3 million soldiers) and North Korea (1.1 million troops) really the third and fourth greatest military powers on the planet?

Maybe not – because gear is a big factor, too: the US has 8,700 tanks, 6,400 attack helicopters and 11 aircraft carriers. Although impressive on their own, India's 5,900 tanks, 140 helicopters and sole aircraft carrier don't really stack up – just one example of the vast capability gaps between all those generals.

But money also talks – especially in America. The US spends more than $700bn a year on its military, which is not only more than any other nation, but more than the next 14 biggest spenders combined.

Perhaps it's not just the results, though, but also the commitment that counts. One way to measure this is to consider how much of a nation's GDP (its annual economic output) is spent on the military. In the US this is a pretty hefty figure (about 4.7%). But that's nothing compared with North Korea, which spends more than 20% of its GDP on its armed forces.

Of course, in reality it's not conventional forces that would be likely to settle any full-on modern contest. We live in the nuclear era, after all, and between them these nations have estimated stockpiles of more than 22,500 warheads. Maybe it's worth giving peace a chance for just a little bit longer, eh?

• Valentina D'Efilippo and James Ball's book The Infographic History of the World is published by Collins