Assuming 1 in a 1000 people clip their nails on any given day. That person generates about 5 mg of nail clippings that day. So by my fag packet calculations that is 37 kg of nail clipping every day on this planet for 7.4 billion people on the planet. Seems a small number. Where have i gone wrong.
I’ll start on that as soon as I finish my earwax computations.
You only clip your nails once every 1000 days?
^ Wolverine feet
On the face of your maths, it seems the 5 milligrams of nail clippings is too low. The aggregate mass of nails clipped by the average human per clipping is certainly more than that, by seeveral orders of magnitude; more in the range of several grams. It might be that the average growth of fingernails and toenails per day per human is in the 5 mg range, but you were talking about mass per clipping (which you assume to be once in 1,000 days - I agree with Aquadementia that this is way too seldom), not about mass grown per day.
It seems to me the amount per clipping is irrelevant. Assuming all toenails are eventually clipped (I’m assuming torn off counts), all that really matters is the average growth per day. If I clip less often, I have more per clipping, but still contribute the same amount to average per day.
So how much do toenails grow in a day?
A factoid often
[quoted]
(Scientists Just Figured Out Continental Plates Can Move Up to 20 Times Faster Than We Thought : ScienceAlert)is that nails grow at the same rate that continents drift. They are both about 3mm per month.
Where shall we start?
Let’s say for convenience that the average uncut nail is 15 mm long and weighs roughly 1 gm - about as much as a postage stamp.
So the monthly 3 mm trimming would weigh 200 mg. Ten fingers worth would be 2 gms.
So 7,000,000,000 lots would be 14,000,000 metric tons a month. So about 460,000 metric tons a day.
Okay, some very rough numbers. Let’s call average nail growth rate 3 mm per month. Call average nail thickness 0.36 mm. Call density of fingernails 1.3 g/cc. My widest fingernail is around 1.1 cm across. Flatten out the curve, and I’ll guess that to be around 1.4 cm. 1.4 cm x 0.36 cm x 0.3 cm gives that fingernail producing 0.15 cc of keratin a month, which is around 0.2 grams (rounded.) 10 fingers, pinky nail smaller than the largest but thumbnail larger than the largest (because I overlooked measuring the thumb as the largest and I’m not going to go back and recalculate) so roughly in the range of 2 grams per month for all 10 fingers. Lots of children and women who have smaller fingernails that me, so call it an average of 1 gram per month for everyone in the world, or 7.4 million kilograms per month of nail growth. Assuming that everyone trims their nails to keep the same average length, around 246 thousand kilograms of fingernail would be trimmed every day.
That should be within a power of 2 or so of the actual number, unless I screwed up somewhere along the way. (I’ll leave toenail clippings for someone else to calculate.)
At that (perfectly reasonable) level of precision, toenails = fingernails.
Still 10 for most people, and some nails larger and some smaller than your baseline index finger. So figure 246,000kg of fingernails & 246,000kg of toenails ~=500Mg of daily nail growth.
I think the OP should tackle total daily human poop next. 
that’s 14,000,000 kg (not tons) or 14,000 metric tons, or 460kg/day.
Just realized an error in my math–in the monthly mass calculation I used 0.36 cm for thickness when I should have used 0.036 cm, so all my answers are off by a power of 10-- 0.015 cc and 0.02 grams for one finger per month, 0.2 grams for both hands, 740,000 kilograms per month for the world, 24,600 kilograms trimmed per day.
Given the answer to the OP, how long until Ragnarok?
You could find someone who has saved all of his nails in order to get a beer idea about the mass that one person creates.
This kind of thing invites all sorts of comparisons using various bodily excretions and fluids. Providing weights is well and good but what we really need are comparative measures … e.g. China alone produces enough [insert fluid] every day to fill two Olympic sized swimming pools.
This whole line of questioning sounds like a beer idea to me. As in … came from way too much beer. 
We found it’s always best to convert the final result of any whimsical calculation into units of Peeps - Wikipedia.
They can easily stand as units of mass, volume, or cost. With some work you can use them as units of length, strength, hardness, temperature, and a host of other physical parameters. And, just like subatomic particles, they come in multiple colors.