Tare & containers

Tare is the customer's container weight subtracted from the gross reading. Get it wrong and you overcharge. Snaptare gives you four ways to set it — pick the one that fits your shift.

1. What tare is, briefly

Customer brings their jar. The scale reads gross (jar + product). You subtract the empty jar weight (the tare) to get net — what they pay for. Tared correctly, the customer pays for product only. Skip it and they pay for their own jar.

2. AI tare from the camera

Snaptare's flagship: snap the empty container in the tablet's camera. The on-device vision model recognizes the shape (mason jar 16 oz, kraft bag, paper sack S/M/L, glass bottle, etc.) and loads the matching tare preset in under 500 ms. Confirm with one tap, or override with a manual value.

• Tap Tare → Snap on the active cart's weighing panel.
• Center the empty container in the viewfinder. The frame highlights it.
• Container recognized → preset loaded → confirm.

3. Saved tare presets

Faster than the camera if you have a small inventory of containers (mason jars, paper bags, etc.). Pre-configure presets in Settings → Tare presets:

• Name (e.g. "16 oz Mason"), weight (in grams), optional thumbnail.
• Mark one as the default for quick access.
• Reorder by drag-and-drop in the settings list.

At the till: tap Tare → Preset → tap the matching preset. Done.

4. Voice tare

Holding the customer's jar, hands occupied. Hold the mic and say "this jar" or "ce bocal". Snaptare reads the current scale value, treats it as the tare, and waits for the product refill. When they pour, the net weight calculates automatically.

Equivalent voice phrases recognized:

• EN: "tare this", "this jar", "tare two thirty" (numeric override)
• FR: "tare", "ce bocal", "tare deux cent trente"

5. Manual entry

Tap Tare → Manual on the weighing panel and type a value in grams on the on-screen number pad. Always available, always works. Useful when the camera is occluded or you've memorized the regular's container weight.

6. Forgot-to-tare detection

If the scale reading at the moment you tap "Add" doesn't match a plausible container + product profile (i.e. it looks like product-only), Snaptare shows a soft prompt: "This reads like product-only at 145 g — did you forget to tare?"

The prompt is dismissible — you confirm "Yes, no container" or "Re-tare". It's calibrated to false-positive rarely; if your shop has lots of unpackaged sales (e.g. produce on the scale alone), you can disable it from Settings → Tare → Forgot-to-tare prompt.

7. Container fingerprinting (regulars)

Optional, opt-in per customer. Regulars who bring the same jar week after week can have their container "fingerprinted" — a small visual signature stored on the tablet. Next time they bring it, Snaptare recognizes the jar and auto-loads the precise tare without you snapping it again.

How to opt in:

1. Attach the customer to the cart (multi-cart §4).
2. Tap Tare → Snap, then Save for this customer on the recognized container.
3. Next visit, the camera identifies the jar instantly.

Fingerprints are stored only on the merchant's tablet, encrypted at rest in IndexedDB. They never sync to our backend. Removing the customer (or signing them out) clears their fingerprints.

8. Where the photos go

Nowhere. The vision model runs locally on the tablet. No image bytes leave the device. The model is downloaded once at install (≈50 MB) and cached in the service worker. After that, it operates entirely offline.