Hydrometers & Refractometers
Its best practise to record your gravity readings when homebrewing so that you can monitor when fermentation is complete plus you will be able to calculate what the abv is from these gravity reading at the start and end
Its best practise to record your gravity readings using hydrometers / vinometers / refractometers when homebrewing so that you can monitor when fermentation is complete plus you will be able to calculate what the abv is from these gravity reading at the start and end