Wet weight and number of worms conversion

Hello all,
I am new to the worm field and looking for the conversion of the wet weight of the worms to the number of worms. I know that it is dependent on the age of the worms, I am looking for the wet weight around 2nd or 3rd of the adult worm. Thank you.


it could be that the lack of replies is a result of the Christmas break (looking at things positively that is)…but a reasonable starting point for calculating this would be this (much) earlier forum discussion;


Some of the later contributions do mention the possible mass of a worm (with the proviso that their density is assumed to be equal to that of water, which it probably isn’t).

However, note that 1µm3 is, in fact 1 x10-9mm3.

Assuming approx. 2 x 10-6 g (2µg) per worm (from David Hall’s calculations based on figure 4 of Knight et al. (2002), then 1000 L4 worms would weigh in at 2mg, which seems at lot? I cannot access the figure because of an error on the site, perhaps you can?

I assume that the calculation is actually, one worm weighs approx. 20ng e.g. volume of 20 x103µm3…that is 20 x 10-9 cm3 and hence 20ng.

A rough “back of the envelope” estimate in the lab could be obtained from pooling a number of plates of L3 worms, pelleting them and then weighing the pellet. resuspend in a known volume and count an aliquot by eye… But obtaining enough to weigh directly might be approaching industrial scale production.


just seen this paper,;


and they show a graph which is more in line with David’s original calculation of 2 x 10-3mm3 per worm! Their data suggests that the probable mass of an L4 worm is 1µg after ~40hr @ 20 degrees! …perhaps you could weigh a pellet of worms and then count an aliquot.

Sorry for the mixed messages…still recovering from Christmas…