How much caffeine does a bag of coffee have?

Caffeine is water soluble. The longer coffee is in contact with water the more it's extracted.

Caffeine content is more a factor of brewing. The longer the brew, the more caffeine. Cold brew takes 12-24 hours to extract, a typical batch/drip coffee brew method takes 4-8 minutes, and espresso shots are about 25-30 seconds.  

• Batch brewing is high as is cold brew, pour over a little less, and espresso is lower; especially a single shot 
• Average 8oz cup of batch brew is approx. 120-180 mg, a double espresso is below 100mg
• Also, the more coffee used (dose), the more caffeine. A single shot espresso is lowest, but a double has more, but not as much as a drip brew
• Roast has very little effect on caffeine content. A darker roast might lose a minuscule few percent of caffeine. Caffeine breaks down at 460.4 degrees Fahrenheit. Coffees are roasted to the low to mid 300 degrees Fahrenheit
• Our decaf is internationally certified by Swiss Water to be 99.9% caffeine free
• Robusta genetics has far more caffeine. We deal only in 100% Arabica

Brewing has the largest effect on caffeine and how it makes you feel: Not the beans, roast, country of origin, nor the variety genetics (one exception being Robusta). So, the longer the brew the greater the buzz. The shorter the brew the gentler the buzz.