Our standard spool used for 500g and 1kg spools of material weighs approximately 290g.
You can estimate the remaining filament on your spool by weighing it in grams and subtracting 290g from that total. The result is the approximate weight of material left on your spool.
Our 4kg spool weighs 925g. So, to determine remaining filament on our 4kg spool, subtract 925 from the total weight of the spool and filament in grams. (1kg = 1000g)
So, our full spool of PLA, for example, would weigh:
1kg spool = 1290g or 1.29kg
4kg spool = 4925g or 4.925 Kg