tsp conversion to mL

[MiguelEnfermo]

So I would like to use a syringe to measure my GH nutes instead of the clumsy measuring spoons. My hands are not as steady as they once were. My USA tupperware type of measuring spoon set (not UK) says ON the tsp handle that 1 tsp is 4 mL. When I fill the spoon with water and pull it out with a syringe it shows dead on 4 mL.
When I google it, or use my conversion calculator on my Windows laptop, it says that 1 tsp is 5 mL. I looked around the GWE site and couldn't find anything that clarifies this.
Any input is appreciated as always.
Thank you!

[Gator]

As far as I know a tsp is equal to 5 ml

[MiguelEnfermo]

I uploaded a photo of my teaspoon handle.

[MiguelEnfermo]

[BigN69]

GH IS WHAT IM USING. It’s on the bottom of the instructions to consider 1 teaspoon = 5 ml. I use a different syringe for each.

[Orggrwr]

Measuring spoons are notoriously inaccurate. Depends on the manufacturer. Syringes are much better. 1 teaspoon equals 5 ml.

[MiguelEnfermo]

Into the recycling bin they go. Thanks all!

[apacin0]

I've been using a 1/2 tsp measuring spoon for nutes, but a 1ml dropper for the PH down. I just used my dropper and measured two scoops water and it came to >3ml. If I used the dropper to put water on top of the spoon I could squeeze 3ml on it (overflowing). So they are kinda close with heavy scoops, but we can't easily keep a full measured spoon all the way from the bottle to the res. I too will get a syringe. Thanks!

[Ckbrew]

Use metric. 5ml.

[Speedygreen]

Yep 5ml is whit I've used forever. Says it on the bottle and has never failed

[Bowhunterwoody]

I've always used 5 ml = 1 tsp. Measuring spoons are supposed to be only filled to level. With solids they should be scraped off on top with the back of a knife. I like 1, 3, and 5 ml. Syringes.

[apacin0]

Oops forgot I have a shot glass sized measuring cup from Hydrofarm I bought years ago. It has both ml and tsp.