1 liter of water is very close to 1 kg. So, you can use that as a reference and use your hand to lift that and the other object by turns and approximately sense which is heavier.

To weigh approximately 1 kg without a scale, you can use common household items with standardized weights as a reference point. The most reliable method is using water: one liter of water weighs exactly 1 kg (not including the weight of the container). You can use a standard measuring jug or even a 1-liter soda bottle to find this measurement. If you don't have a liquid measuring tool, you can look for unopened pantry staples like a standard bag of sugar or flour, which is often sold in 1 kg or 2 lb (approx. 0.9 kg) increments. Another creative method is to use a balance scale made from a clothes hanger and two bags; if you place a known 1 kg item (like two 500ml water bottles) in one side, you can add your target material to the other side until they are perfectly level. For small adjustments, remember that 400 standard paperclips or about 200 nickels (each weighing 5g) equal roughly 1 kg. While these methods are not scientifically precise, they are excellent for general household needs or estimated shipping weights.