Quite often, you can find some exotic length units in historical or classical works.
For example, "stade", used in the ancient world, or "it's 5 leagues till Paris".
I always wanted to estimate and understand - how much it is in meters.
So here is the calculator to convert to and from meters.
The main advantage is that it uses the data from the handbook Exotic length units.
If you add a new entry (for that, you need a name of a length unit and its length in meters), it will appear in the result table at once.
The result table consists of five columns. The name of the unit is in the first column. The unit value in meters is shown in the second column of the table. The value obtained by converting the given amount as the amount of this unit to meters is shown in the third column. The value obtained by converting the given amount as the number of meters to units (opposite to the previous column) is shown in the fourth column.
The handbook, of course, should not be abused. Also, there are individual calculators for the standard measurement system.
Imperial to Metric and Metric to Imperial measures of length converter
Russian Length Unit Converter
so don't add yards and feet to the handbook. But, you surely may add "Li" which are famous for the proverb "A journey of a thousand li starts beneath one's feet"