Bread Hydration Calculator (why I made it)

I’ve been baking sourdough on weekends for a couple of years. Not a professional, just someone who likes the ritual and the smell. But every Saturday I’d run into the same small frustration: I’d write down a recipe that says “75% hydration” and then stand there doing mental arithmetic while flour dust got everywhere. How much water is that for 500g of flour? I usually grabbed my phone, opened the calculator, then double-checked myself because I didn’t trust my math under time pressure.

One day I actually mixed the dough before realizing I’d added 350g of water to 500g of flour — that’s 70%, which is fine, but not what I wanted. The dough was okay, but a bit stiffer than intended. And that’s when I thought: I make tools for a living, why don’t I have a simple tool for myself?

I looked around for existing bread hydration calculators. There are a few, but honestly they were either cluttered with ads and sliders for “temperature compensation” (I’m not there yet), or they made you input weird settings like “desired dough yield” — which I don’t care about. I just want flour in, hydration % in, and water grams out. Or sometimes I have water and hydration and need flour. Nothing had that clean back-and-forth without unnecessary fluff.

So I built a tiny no-nonsense page. It does exactly three conversions:

1. You know flour weight and target hydration % → get water weight.
2. You know water weight and hydration % → get flour weight.
3. You know flour and water weights → get the hydration percentage.

No extra fields, no account, no ads. Just a clean calculator with a simple interface. I used it for three weeks before sharing — it caught my own typo twice when I accidentally entered flour as 450 instead of 550, and the hydration % instantly told me something was off. It’s also helpful for scaling a recipe: if I have 720g of flour and want 82% hydration, I don’t have to dig out a notebook.

It’s not a flashy tool, and that’s the point. I wanted something that feels like a reliable measuring cup — not an app with notifications. It’s static, works on a phone, and doesn’t require an internet connection after loaded.