Zerena Store — A package-free, zero-waste bulk shop | zerenastore.com
Tare is the empty weight your container brings to the scale — from 30 g for a cotton bag to 700 g for a thick-walled glass jar — and the tare button is what keeps it off your bill.
A 1-litre glass jar weighs about 400–700 g empty, depending on wall thickness. That spread is the widest of any common refill container, and it matters at the till: an untared heavy jar adds nearly three quarters of a kilo to the scale before a single gram of food goes in.
At the light end sits the cotton produce bag at 30–60 g of tare. For light goods — anything where a few hundred grams would be a large share of the purchase — the bag is the rational choice, because the tare rounds away instead of distorting the net weight.
Liquids usually travel in a kept 1-litre HDPE bottle at 30–50 g. Beyond the weighing advantage, every refill of that bottle removes 30–50 g of single-use packaging from the basket, which is the format's original point.
On narrow screens, swipe or scroll the plate sideways.
The mechanics are one button. Empty container on the scale, press tare, the display returns to 0.00, then fill and reweigh. The receipt shows net weight only — filled weight minus tare — and that net figure is what the unit price per kilo multiplies, as explained on the price per kilo page.
Choosing by tare means matching container to density. Honey at about 1.4 kg per litre outweighs even a 700 g jar two to one, so heavy glass is forgiven; long-grain rice at 0.85 kg per litre barely outruns it. The lighter and less dense the goods, the lighter the container should be.
Once home, the container's job continues: dated and rotated by the shelf-life months of its contents, it cycles back for the next refill. The rotation procedure is on the bulk shelf life page.
Further reading