function getBaseLog(x, y) {
  return Math.log(y) / Math.log(x);
}

Knowing your actual body fat percentage is a key method for assessing your health. BMI (Body-Mass-Index) ratios are pointless; it doesn't account for people with the same height but different body structures. For example, a 6 foot man with broad shoulders and big joints would be seen as overweight while another 6 foot man with small joints and

The actual formula is as follows:

For Men:

495/(1.0324 - 0.19077(LOG(waist - neck)) + 0.15456(LOG(height)))-450

For Women:

495/(1.29579 - 0.35004(LOG(waist + hip - neck)) + 0.22100(LOG(height))) - 450

Just perform a set to failure at the gym, plug in your numbers above, and you'll find out your max!

NOTE: like any formula, this isn't perfect. So I'd recommend plugging in anything ranging from your 5-rep-max to 8-rep-max for the most accurate results.