To calibrate a 30 kg kanta, set it on a level counter, zero it, then load certified test weights at about a quarter, half and full capacity and compare each reading. For a kanta that reads in 5 g steps, OIML R 76 allows no more than 15 g of error at full load once the scale is in service. A reading outside that needs a span adjustment, and on a stamped shop scale only a registered repairer may make it.
Kanta is the everyday Hindi word for a weighing scale, so a weight kanta in English is simply a weighing scale. Many shopkeepers also call a 30 kg counter scale a taraju.
What a 30 kg kanta is and how it reads
A 30 kg kanta is a table-top shop scale for grain, vegetables, sweets and parcels. The Omace Om-TT-Running SPR 30 kg kanta reads 30 kg in 5 g steps on a 240 × 300 mm stainless steel pan.
Two numbers on the nameplate decide how a kanta is judged. Max is the capacity, and e is the verification scale interval used to measure its errors. OIML R 76 requires a trade scale's nameplate to show its accuracy class, Max, Min and e.
Divide Max by e to get the number of steps. A 30 kg scale with e = 5 g has 6,000 steps, which places it in medium accuracy class III under R 76. Omace's Om-TT shop scales use these figures: the series is a Legal Metrology approved model, and its approved 30 kg model is approved in accuracy class III with e = 5 g and Min 100 g. On a class III scale, e equals the display step.
How much error a 30 kg kanta may show
R 76 sets its limits in multiples of e, and the limit in service is twice the limit at first verification. For a 30 kg kanta with e = 5 g:
| Load | At first verification | In service |
|---|---|---|
| Up to 2.5 kg | ±2.5 g | ±5 g |
| 2.5 to 10 kg | ±5 g | ±10 g |
| 10 to 30 kg | ±7.5 g | ±15 g |
| Corner test, 10 kg on each quarter | ±5 g | ±10 g |
Repeat readings of the same load must also agree within these limits. R 76 lets the zero move by no more than one e, here 5 g, for each 5 °C change in room temperature. Recheck zero after the shop warms up or the AC comes on.
Test weights you need for a 30 kg kanta
OIML R 111 names class M1 weights for medium accuracy class III scales. A 20 kg M1 weight may be off by no more than 1 g, a 10 kg weight by 0.5 g and a 5 kg weight by 0.25 g.
R 76 limits a test weight's error to one third of the scale's permitted error at that load. At 30 kg the first-verification limit is 7.5 g, so the weights used may be off by 2.5 g at most. A 20 kg and a 10 kg M1 weight together stay within 1.5 g.
You do not need 30 kg of certified weights for an on-site test. The Legal Metrology (General) Rules, as amended in July 2026, let any steady load replace part of the weights when a scale is tested where it is used, provided certified weights make up at least half the capacity. For a 30 kg kanta that means at least 15 kg of certified weights, falling to 10 kg when repeat readings agree within 0.3 e.
For a quick daily check, keep one known load, such as a sealed bag first weighed on a verified scale, and put it on each morning.
Calibration steps for a 30 kg shop scale
- Charge and place it. Charge the built-in battery, then set the scale on a firm, level counter away from fans and drafts.
- Zero it. Switch on with an empty pan and wait for 0. If it does not settle at 0, check that nothing touches the pan.
- Check repeatability. Put 15 kg on three times and note each reading.
- Check the range. Load about 7.5 kg, 15 kg and 30 kg in turn, and compare each reading with the table above.
- Check the corners. Place 10 kg, one third of the capacity, on each quarter of the pan in turn.
- Check tare. Put an empty crate on, press TARE, add 10 kg and read the net weight.
- Check the return to zero. Unload the pan and confirm the display goes back to 0.
- Write it down. Note the date, each load and each reading, so slow drift shows up over the weeks.
If every reading is inside the in-service limits, the scale needs no adjustment. If the error grows steadily as the load rises, the span is off and needs adjusting with the weight the manual names. The Ace PS-30 30 kg weighing scale, for example, lists manual calibration in its specification. On an Omace digital scale that is not stamped, holding TARE for about 5 seconds opens calibration mode, and the calibration weight it asks for differs by model. Switch the scale fully off once and back on before you start. Omace Om-TT shop scales leave the Bagru factory verified and stamped, so their calibration is sealed and only a registered repairer may change it.
When to adjust a kanta, and who may do it
OIML R 76 requires the calibration adjustment of class II, III and IIII scales to be sealed. On a stamped shop kanta, the Legal Metrology seal covers it, and breaking the seal means the scale must be verified again. Rule 27 bars a repaired scale from use until it has been re-verified and stamped.
Since 1 May 2026, anyone who repairs weighing instruments needs a registration certificate from the Controller of Legal Metrology under Section 23, in place of the earlier licence. Ask to see it before handing over a trade scale.
Legal Metrology rules for a shop kanta
Section 24 of the Legal Metrology Act, 2009 requires a scale used in any transaction to be verified before use. Section 33 fines the use of an unverified scale ₹2,000 to ₹10,000, and a repeat offence can bring up to one year in prison as well.
Rule 27 of the Legal Metrology (General) Rules, 2011 sets re-verification every 24 months for weights, beam scales and counter machines, and every 12 months for all other weights and measures. An electronic kanta is not on the 24-month list, so it is re-verified every year.
A kanta of up to 50 kg can get its first verification in the state where it was made or imported, provided it is not dismantled and needs no calibration before use, under the 2021 amendment to Rule 27. Re-verification then happens in the state where the scale is used. The same amendment exempts scales that industries use internally, without affecting the quantity delivered to customers, from re-verification.
Daily habits that keep a kanta accurate
- Zero before the first sale. Switch on with an empty pan and wait for 0.
- Load the centre. Place goods in the middle of the pan, because corner loads read differently.
- Never drop goods. Omace's manuals warn against dropping goods on the pan or loading it past capacity.
- Keep water off the electronics. Wipe the pan with a damp cloth and keep water away from the display and keys.
- Charge on time. Charge the battery when the low battery sign shows.
- Mind the temperature. Use the scale between 10 °C and 40 °C, the range Omace gives for its shop scales.
- Recheck after a move. A new counter can change the reading, so test with a known weight after moving the scale.
Omace 30 kg kanta options
Omace sells four 30 kg counter scales (prices include GST, October 2026):
| Model | Capacity and step | Pan | Customer display | Price |
|---|---|---|---|---|
| Omace Om-TT-Running SPR | 30 kg × 5 g | 240 × 300 mm steel | Back of the body | ₹3,000 |
| Omace Om-TT-Running SPD | 30 kg × 5 g | 240 × 300 mm steel | On a pole | ₹3,100 |
| Omace Om-TT-Mini SPR | 30 kg × 5 g or 20 kg × 2 g | 175 × 225 mm steel | Back of the body | ₹2,500 |
| Ace PS-30 | 30 kg × 1 g or 15 kg × 0.5 g | 190 × 160 mm steel | Single backlit LCD | ₹1,799 |
The Om-TT models run on 220 V with about 2 days of battery backup; the Ace PS-30 runs on AAA batteries or an adapter. The Omace Om-TT-Running SPD vegetable weighing machine lifts the customer display on a pole for sabzi stalls, and the Omace Om-TT-Mini SPR double display weight machine suits smaller counters. The full range is in weighing machines for shop.
For billing scales, see price computing scale calibration; for heavier platform scales, see what a legal for trade weighing scale needs. The general method is in how to calibrate a digital weighing scale.
Omace Brands Private Limited has made and supplied weighing scales in India since 1994 from Bagru, Jaipur. Every Omace scale is checked before dispatch, and store purchases carry a 2-year warranty on manufacturing defects. More about Omace. Omace scales are made in India. As a manufacturer, Omace Brands Private Limited holds ISO 9001:2015, ISO 13485:2016 and EU MDR quality certificates, and CE and US FDA compliance certificates; each is listed with its certificate number on the Omace certificates page. Omace shop, platform, chicken and crane scales leave the Bagru factory verified and stamped by Legal Metrology.
