A calculator that can deal with distributions ergonomically, to allow users to easily arrive at fermi estimates that incorporate uncertainty. Tips: ■ The boxes represent the 90% confidence interval (5% to 95%) of your distributions ■ Swipe left or right to duplicate an input Try this example estimating the number of grams lost with a month of exercise lifting: 10 to 30 kg lifted per exercise × 0.25 to 0.75 meters lifted per exercise × 9.81 gravitational constant, to get to Jules (swipe left at the bottom to duplicate the input) × 10 reps per set × 3 to 4 sets per exercise ÷ 15% 35%, wild guess on chemical to physical efficiency conversion ÷ 4, jules to calories ÷ 6K to 8K, calories burnt to lose one gram of fat × 7 to 15 exercises in a gym session × 2 to 4 times a week × 4 weeks a month ÷ 10% to 30%, wild guess for share of loss that is due to the direct physical exercise (as opposed to higher burn rate, cost of building muscles, etc.) = ¿ to ? grams lost with the above exercise regime in a month