TLDR; eh about 1kg per 1mm of wetsuit but be careful. A general starting spot but be careful and go at your own risk*. That’s our disclaimer lol.

How much weight to use while spearfishing is probably one of the most under-spoken aspects of the sport that I’ve found. I’m not sure if it’s because people are afraid to give their opinion or if it’s because they don’t think it’s a big deal, either way it was super frustrating to research when we were first getting started. We hope that this article serves to help you understand it a bit better as you’re getting started.

The first day going to buy weights was super confusing for us. We’d searched Google and YouTube high and low trying to find out even just approximately how much weight we’d need to use only to find the same answer time and time again, “you need enough to allow you to dive but not enough to make you sink. You’ll need to figure it out on your own.”

To us this was a really frustrating answer cause it didn’t give me anything to go off of. So here’s a quick guide that we use now and would suggest to others getting started. Please keep in mind though start with too little and add more that way you don’t get the watery grave. These are just suggestions and go at your own risk… Okay that’s our disclaimer. Let’s get into it.

• Weight: Okay, so our general rule of thumb to measure how much you need is 1kg / 1mm of wetsuit. If that sounds simple, well it is. We’ve found that diving between 5-10m of water 3kg for a 3mm wetsuit works great. Same with 5kg for 5mm. Heck, I wear a 7mm top and 3mm bottom which is a rough average of 5mm and I wear 5kg. It may seem simple, but here’s a couple of other things to think about when measuring you weight.
• Body Type: We’re all in relatively decent shape, as you’d expect from most spearfisherman so there’s not an exorbitant amount of body fat on us. If a person is relatively overweight they’re definitely going to have to add more weight to their belt. Even then I might still start with this general rule of thumb and add more as you need.
• Depth: This is where weight really starts to make a difference and you want to make sure that you’ve got a correct amount on. We’ve noticed that when diving deeper than 8-10m we’ll start to become buoyancy negative (meaning you start to sink). You’ll want to be extra careful you don’t have too much weight on when diving at deeper depths, especially if you’re new. If you’re concerned you might have too much, but you’re finding yourself spending a lot of energy trying to get down due to buoyancy, then we might suggest a drop-weight. 

Every time we take someone new out with us now we measure how much weight they need using this method. Not sure why it works or if there’s anything scientific about it, but it’s what we’ve used and hope that it’s helpful for you.

Because we’re sure someone will ask, “Doesn’t height matter?” It probably does but we’re not sure to what extent. We’ve taken people out that are anywhere from 5’6” to 6′ 2” and this method has worked as a general with everyone.

If you have a better way of measuring, please let us know! We’re always trying to learn and refine the craft. Otherwise we hope this helps and happy hunting!