Comparing power: Studio lights vs. speedlites / speed lights

Speedlights pack a huge amount of light for the size. Very portable, and loaded with sophisticated features, owning a speedlight is a must. A simple choice. Studio lights and the larger portable flashes such as the Profoto B1 TTL flash (B&H / Amazon) , offer a lot more power than speedlights. Exactly how much more powerful, isn't all that easy to gauge. There's very little available as direct comparison. Even the specs aren't directly comparable. Speedlights' power is given as a Guide Number (GN), and studio  Read more inside...