How Do I Convert Litres to Kilograms for Silicone Rubber?

Understanding Density and the Conversion Formula

Silicone rubber is typically supplied in kilograms, yet project guides and moulds often quote volumes in litres. To bridge this gap, use the material’s density—usually between 1.05 and 1.20 kg per litre for liquid silicones. The basic formula for conversion is:

• kilograms = litres x silicone density

For example, if you have 4 litres of silicone rubber at 1.10 kg/litre density, you would need 4.4 kg.

Practical Steps for Accurate Measurement

To get a reliable result, always check your particular product’s technical data sheet or packaging for the most precise density value, as formulations can differ. If in doubt, use an average value between 1.05 and 1.20 kg/litre for a safe estimate. It’s usually better to slightly overestimate rather than run short part way through your pour.

If you’re using a bi-component silicone, such as “Liquid Mould” – Casting Liquid Silicone Rubber, remember to measure both parts by weight according to the manufacturer’s specified ratio.

When This Matters Most

Precise conversion is particularly important when creating large or multiple moulds, or when ordering more expensive platinum-based silicones such as “Pure Mould” – Translucent Liquid Silicone Rubber. This ensures you avoid waste and achieve consistent results across your project.