* Hair texture: Hair thickness and curl pattern significantly impact how long it appears. Straight hair will hang straight down, while curly or wavy hair will have more volume and appear shorter.
* How the hair is measured: Is the measurement taken from the scalp to the ends, or from the crown of the head? This can make a difference of several inches.
* Where the hair is measured: Measuring from the top of the head might be different than measuring from the hairline.
General Estimate:
A good general estimate is that 26-inch hair on someone who is 5'7" would likely reach midway down their back. This is just an approximation, and it could be longer or shorter depending on the factors mentioned above.
To get a more accurate idea, you'd need to consider the person's hair texture and how the length is measured.