A scale that handles a kilogram of flour perfectly can be useless for two grams of yeast, and the reason is a property of the instrument rather than a fault.

The Problem With Small Loads

A load cell is designed across its whole range, and its error does not shrink proportionally at the bottom of that range.

A scale accurate to within a gram is accurate to within a gram whether you are weighing 1,000 grams or 3 grams. At the top that is a rounding error. At the bottom it is a third of the ingredient.

A Second Scale

The proper answer for anyone doing this regularly. A small scale with a low capacity and a fine increment resolves small quantities properly.

Ranges spanning both high-capacity kitchen models and finer precision models, of the kind in the escali scale line-up, exist because one instrument genuinely cannot do both well.

Where This Bites

• Yeast, where a couple of grams changes a proof time substantially
• Salt in small doughs, where percentages are tight
• Spices, particularly anything potent
• Chemical leaveners in small batches
• Gelatine and setting agents
• Anything where the recipe specifies fractions of a gram

The Workarounds

Weigh a larger quantity and divide. Twenty grams of yeast weighed accurately and split into ten portions is considerably more reliable than weighing two grams ten times.

Weigh by difference: put the container of yeast on, tare, spoon out until the display reads minus two grams. That uses the scale’s ability to detect a change rather than to measure an absolute small mass, which it does better.

Or use volume for the very smallest amounts, where a level teaspoon is more consistent than a scale operating below its useful range.

The Physics of Why Not

Stretching a single load cell to cover fifteen pounds and also resolve a tenth of a gram would require the sensor to work across a range of well over a hundred thousand to one.

That is not what inexpensive strain-gauge sensors do. A jewellery scale weighs very little precisely because its cell is designed for a narrow range.

Draughts and Vibration

At small weights, environmental effects that are irrelevant at a kilogram become significant.

An extractor fan, an open window, a hand resting on the worktop, or somebody walking past can all move the last digit. Precision scales have draught shields for exactly this reason.

Check the Stated Minimum

Some manufacturers publish a minimum weight below which readings are not guaranteed. Where they do, that figure is more useful than the resolution.

Where they do not, a reasonable working rule is to distrust anything below about twenty times the increment.