How many amps do I actually need to jump-start my car?

For most four- and six-cylinder gas cars, a unit rated around 1000 peak amps (such as the NOCO GB40) is sufficient. Larger gas engines and diesels benefit from 2000A or more (NOCO GB70/GB150). Note that 'peak amps' marketing figures vary widely in how they're measured across brands, so treat very high headline numbers from value brands with some skepticism and match the unit to your engine size.