There's no need to feel ashamed of your bad math! And there's also no need to have errors in your calculations. Our friends at GotMead.com have the perfect tool for planning and tending to all the various needs of your mead. Whether it's an accurate gravity, the sugar amount, or... well, play around with it for yourself and you'll see how easy it is.
If you've never used the mead calculator, you're missing out! The thing is basically a mix between magic and science fiction and a TI-83. https://gotmead.com/the-mead-