This is for the people using Seachem's Flourish line of products. It's a Microsoft Office Excel based Seachem Dosing Calculator/Chart that is based on the following dosing schedule. It calculates the formula out to 4 decimal places and then rounds them to one decimal place. It uses US gallons for it's calculations.
This calculator will work for most aquariums the way that it is set up now, but it can be easily changed.
If you want to dose a small aquarium and/or you want more accuracy, you can highlight each cell that shows the dosing amounts by clicking on the mouse and holding down on the Ctrl key. Then click on the increase decimal places button to change how many decimal places that you want it to show. It is set at 1 decimal place now. The gallons amount that you enter can have many decimal places.
Most people can't use that accuracy because they don't have the correct equipment. That's why it is set up for 0.1 mL. Most of us can measure down to 0.1 mL.
The gallons to liters and the liters to gallons calculators work too. Again, they are based on US gallons.