# Dosa batter calculator

Source: https://howtomakedosa.com/dosa-batter-calculator/
Updated: 2026-09-25

Tell it how many dosas you want and how warm your kitchen is. It scales the 4 : 1 rice-to-dal recipe to the gram and tells you how long to soak and ferment.

## Your batch

## Batch sizes at a glance

The same numbers the calculator uses. Everything scales from 25 g of dry grain per dosa, which gives one 80 ml ladle of batter.

| Dosas | Idli rice | Urad dal | Fenugreek | Salt | Grinding water |
|---:|---:|---:|---:|---:|---:|
| 10 | 200 g | 50 g | 2.5 g | 5 g | 165 ml |
| 20 | 400 g | 100 g | 5 g | 10 g | 325 ml |
| 30 | 600 g | 150 g | 7.5 g | 15 g | 490 ml |
| 40 | 800 g | 200 g | 10 g | 20 g | 650 ml |

Grind the dal with **46%** of the water, and the rice with the rest.

## Fermentation time by temperature

| Kitchen temperature | Soak | Ferment until doubled |
|---|---:|---:|
| 18 °C / 64 °F | 7 h | 30 h or more; warm it |
| 20 °C / 68 °F | 7 h | 22–26 h |
| 24 °C / 75 °F | 6 h | 15–18 h |
| 28 °C / 82 °F | 5 h | 10–12 h |
| 32 °C / 90 °F | 5 h | 7–8 h |
| 36 °C / 97 °F | 4 h | 5–6 h |

These are starting points. Batter is ready when it has doubled, not when the clock says so. In a cold kitchen, see [fermenting in cold weather](https://howtomakedosa.com/ferment-dosa-batter-in-cold-weather/).

**How the numbers work:** Rice is 80% and urad dal 20% of the dry weight. Fenugreek is 1%, salt 2%, and grinding water 65%. Fermentation times come from the [master recipe](https://howtomakedosa.com/)'s table, interpolated between rows.

## Keep going

- [Batter not fermenting](https://howtomakedosa.com/dosa-batter-not-fermenting/): The seven causes, most likely first, with a test for each and a way to save the batch.
- [Fermenting in cold weather](https://howtomakedosa.com/ferment-dosa-batter-in-cold-weather/): Oven light, proof setting, Instant Pot or a cooler: the temperature each one holds and how long the batter takes.
- [Idli](https://howtomakedosa.com/idli/): The same batter, not thinned, steamed for 10–12 minutes. What makes idli soft instead of dense.