It's tights season once again.
But here's the question we have to ponder every autumn (not to mention spring) morning: Do we need thick woolly tights or just a 15 denier pair to keep off the chill?
Mathematician Dr James Hind has come up with a formula to find the perfect denier of tights for the weather, based on studying his wife's tights collection.
The formula takes into account the temperature and wind strength to find the perfect thickness of tights to keep you warm but not overheated.
"It started when BBC Radio Nottinghamshire asked me if I could come up with a tights forecasting equation to help listeners get dressed in the mornings," Dr Hind, a lecturer in statistics at Nottingham Trent University, told the Daily Mail.
Dr Hind asked his wife what denier tights she wore each day and kept a note of the temperature. He then plotted the points on a graph. (Dr Hind's wife clearly has a lot of tights - and a knack for always choosing the right thickness for the prevailing wind).
He created the formula below so the results would go from 0 to 110 denier.
D is the denier of tights required, W is the wind speed and T is the temperature.
But you don't have to worry too much about how to put the formula into practice as Dr Hind has used it to create an Excel spreadsheet, which is available on the Nottingham Trent website, on which you can input details of the day's weather and be given the result: i.e. what denier tights you should be wearing.
Dr Hind is convinced it's a winning formula.
"No matter how cold or how warm it gets, the equation will work," he insisted.
When it's only 10 degrees centigrade and the wind speed is 10 mph, his formula suggests 30 denier tights.
Seems about right.