How to measure

A good report is one anyone can check. Here’s how to make yours hold up.

Package weight

1. Use a scale you can trust. The store’s produce scale is best: stores must keep them accurate and the state inspects them. Your own kitchen scale works too.
2. Check the scale with a known weight. A 100 g or 500 g calibration weight is best (they cost a few dollars online). Ten US nickels work too: they weigh 5.000 g each, so 50 g together. Note what the scale shows. Within 1 g or 1% it counts as accurate. If it reads low, we raise your reading by the same proportion; if it reads high, your reading is left alone, because the package then weighs even less than it showed. A scale more than 10% off can’t be used.
3. Zero the scale first, with nothing on it.
4. Photograph the label and the reading together, in one sharp shot.
5. Know what the result means. The label states the net weight: the food only. Your reading includes the tray and wrap. So if the reading is under the label, the food is short by at least that much. If it reads over, that doesn’t prove the package is full, only that it isn’t provably short.

Unit price tags

1. Photograph the whole shelf tag: the price, the size and the unit price.
2. Type in the shelf price, the package size and the unit price exactly as printed, with the unit the tag uses (per oz, per lb, each, per 100 ct, per sq ft…).
3. We divide the price by the size, converting units when needed. Tags are rounded, so a difference within half a cent or 1% counts as correct.

Checkout prices

1. Photograph the shelf tag or the store’s ad before you buy, with the item in view.
2. After paying, photograph the receipt line for that item.
3. Enter the price of one item on the tag and on the receipt. Many states require stores to honor the lower price, or give the item free, when the register charges more; ask at the service desk too.

Fuel pumps

1. Use a container with clear volume marks. A certified 5-gallon test can is ideal; a new gas can’s molded lines are rough, so we allow 2% for measuring error.
2. Pump into the container only, stop at a round amount, and photograph the pump display.
3. Set the container on level ground, let the foam settle, and photograph the level against the mark.
4. Only fill approved fuel containers, on the ground, never in a vehicle or truck bed.

Counts and liquids

1. Counts: lay the pieces out and photograph them, with the package showing its stated count.
2. Liquids: pour into a measuring cup on a flat surface and read it at eye level. Measuring cups aren’t exact, so we allow 2%.

Be fair

• Report what you measured, nothing more. Results say “short by at least,” not “fraud.”
• Don’t photograph people. Stores can ask you to stop filming or taking photos; if they do, be polite and stop.
• If you weigh an item someone else reported, add your result to their report, whether it was short or fine.

Making it official

Every state has a weights & measures office (usually in the department of agriculture) that inspects scales and packages. From any report, choose “Prepare a complaint” to get a summary you can send them. NIST’s Office of Weights and Measures lists contacts for every state.