How do I determine # of pearls for a bracelet?

[Ann]

I am in the "thinking stage" of an 11mm round GSS bracelet. I have tiny wrists. Is there a formula to determine how many pearls to buy? I've researched it and realize the size of the pearls takes up a lot of space and the knots do as well. This will be my first dive into nice pearls, so I want to do it right. But also trying to keep the cost down, so I don't want to buy more than I truly need. Any thoughts> Thanks.

 

[pearlsngems]

Using a tape measure, measure your wrist at the place where you would wear your bracelet, remembering that gravity will pull it down toward your hand when you are standing with your hand by your side. To that measurement, add however much length you feel you will need for the bracelet to be neither too tight or too loose.

What number do you come up with?

Also, what clasp do you plan to use and how long is it in mm?

 

[lissyflo]

You’ll need to adjust your wrist measurement to take account of the radius of the pearls too - the larger the pearls the larger the circumference of the bracelet will need to be, as the thread (through the centre of the pearls) will sit further off your wrist. Have I written that so it makes sense?! No idea how to calculate what that might be though

If your wrist is close to a standard size, you could have a look at premade bracelets in your desired pearl size and see how many pearls they include as a guide.

 

[pearlsngems]

Don't adjust the wrist measurement in answering my questions, though. That will enable me to calculate the inside diameter of the bracelet. I am taking into account the radius of the pearls.

 

[pearlsngems]

I did a bunch of calculations, ranging from a slightly small to a very small wrist, taking into account the "comfortable fit" of the bracelet, (which is the number I asked you for in my first post) as well as the fact that an 11mm pearl will add 5.5mm in radius on each side of the bracelet since it's drilled through the center, (if you imagine the bracelet as a circle.)

Anyway, here is what I came up with.

FYI knots tend to be 0.3-0.5mm wide, and the loop of gimp will take up 3-4mm of space on each side of the clasp.
Also 1 inch = 2.54cm

If the number on the tape measure (the circumference of the wrist where the bracelet will hang, plus however much extra length for ease that you prefer)
is ....

• 7.0 inches, then the finished length of the bracelet (including clasp) will be 8.58" or 21.8 cm, and dividing by 1.1 cm (11mm) that means you'll need 18 pearls. 18 pearls x 1.1cm each = 19.8 cm. This leaves 2 cm for your clasp, knots and gimp. If 2 cm seems like not enough space for the clasp you prefer plus knots and gimp, then go with 17 pearls. That will leave you 3.1 cm for a larger clasp, plus knots and gimp.

• 6.5 inches, then the finished length of the bracelet will be 7.86" or 20 cm, and you would need 16 pearls, with 2.4 cm (about an inch) left over for your clasp, knots and gimp. Again, if this is not enough space for your preferred clasp etc, go with one less pearl.

• 6.0 inches, then the finished length of your bracelet will be 7.36" or 18.7 cm, and you will need 15 pearls with 2.2 cm left over for clasp, gimp and knots. If this is not enough space for your preferred clasp etc, go with one less pearl.

• 5.5 inches, then the finished length of the bracelet will be 6.85" or 17.4cm, and you will need 14 pearls, with 2 cm left over for clasp, knots and gimp. If this is not enough space for your preferred clasp etc, go with one less pearl.

• 5.0 inches, then the finished length of the bracelet will be 6.4" or 16.3 cm, and you will need 13 pearls, with 2cm left over for clasp, gimp and knots. If this is not enough space for your preferred clasp etc, go with one less pearl.

• 4.5 inches, then the finished length of the bracelet will be 5.88" or 14.9 cm, and you will need 12 pearls, with only 1.7 cm left ver for clasp, gimp and knots. If this is too little go with 11 pearls and choose a slightly larger clasp.

 

[MakingTheGrade]

Amazing math! So kind of you

 

[Ann]

I did a bunch of calculations, ranging from a slightly small to a very small wrist, taking into account the "comfortable fit" of the bracelet, (which is the number I asked you for in my first post) as well as the fact that an 11mm pearl will add 5.5mm in radius on each side of the bracelet since it's drilled through the center, (if you imagine the bracelet as a circle.)

Anyway, here is what I came up with.

FYI knots tend to be 0.3-0.5mm wide, and the loop of gimp will take up 3-4mm of space on each side of the clasp.
Also 1 inch = 2.54cm

If the number on the tape measure (the circumference of the wrist where the bracelet will hang, plus however much extra length for ease that you prefer)
is ....

• 7.0 inches, then the finished length of the bracelet (including clasp) will be 8.58" or 21.8 cm, and dividing by 1.1 cm (11mm) that means you'll need 18 pearls. 18 pearls x 1.1cm each = 19.8 cm. This leaves 2 cm for your clasp, knots and gimp. If 2 cm seems like not enough space for the clasp you prefer plus knots and gimp, then go with 17 pearls. That will leave you 3.1 cm for a larger clasp, plus knots and gimp.

• 6.5 inches, then the finished length of the bracelet will be 7.86" or 20 cm, and you would need 16 pearls, with 2.4 cm (about an inch) left over for your clasp, knots and gimp. Again, if this is not enough space for your preferred clasp etc, go with one less pearl.

• 6.0 inches, then the finished length of your bracelet will be 7.36" or 18.7 cm, and you will need 15 pearls with 2.2 cm left over for clasp, gimp and knots. If this is not enough space for your preferred clasp etc, go with one less pearl.

• 5.5 inches, then the finished length of the bracelet will be 6.85" or 17.4cm, and you will need 14 pearls, with 2 cm left over for clasp, knots and gimp. If this is not enough space for your preferred clasp etc, go with one less pearl.

• 5.0 inches, then the finished length of the bracelet will be 6.4" or 16.3 cm, and you will need 13 pearls, with 2cm left over for clasp, gimp and knots. If this is not enough space for your preferred clasp etc, go with one less pearl.

• 4.5 inches, then the finished length of the bracelet will be 5.88" or 14.9 cm, and you will need 12 pearls, with only 1.7 cm left ver for clasp, gimp and knots. If this is too little go with 11 pearls and choose a slightly larger clasp.

Wow, thank you sooo much. I knew my brilliant PS's would have the answers. Thank you all for responding. I have some serious thinking to do.

 

[pearlsngems]

The comfortable length as measured with the tape measure is the circumference of the bracelet before we adjust for the fact that the pearls are spheres that are center drilled.

Imagine the comfortable length of the tape measure as a large circle drawn on a piece of paper.
I first calculated the radius of that large circle using the formula c = 2πr (circumference = 2 times π times the radius. For π I use 3.14, which is close enough for our purpose.)

The pearls are 11mm.
Picture a number of 11mm circles arranged all around the circumference of the large circle-- many little circles around one large circle.
Picture them center drilled with a thread running through the hole, connecting them. The length of that thread is the new circumference that we have to calculate in order to know the finished bracelet length, so that we can figure out how many pearls we will need.

But how do we calculate the length of the thread?

Just look now at two of the pearls, on opposite sides of the circle. Because they are drilled through the center, each of the two pearls adds half its width-- 1 radius-- to the large circle. So now we have to add the radius of those 2 pearls to the radius of the large circle, and that gives us the radius of the thread circle. [Edit: I noticed an error here-- I have to add the radius of only one of those pearls to get the thread radius. Will correct the math and either update this post, or post a new post further down.]

Then we use the radius of the thread circle to calculate the circumference of the thread circle, using the same formula (c = 2πr).

The result is the circumference of the finished bracelet when it is clasped-- which is its length when unclasped.

Whether we are working in inches or centimeters, we divide the circumference / finished length of the bracelet by the diameter of the pearl (in this case, 11mm = 1.1cm = .433") to get a number. That number is how many pearls in a row it takes to make that finished length. It is never a round number, and you can't use a fraction of a pearl, and you have to allow for clasp, knots and gimp.

So multiply the number of pearls by their diameter and you will know how much of the finished length will be taken up by the pearls. Subtract that number by the finished length and now you know how much space you have left for the clasp, knots and gimp.
Reiterating, knots tend to be 0.3-0.5mm each, and the little gimp loops will be 3-4mm on either side of the clasp. As for the length of the clasp, if you have one, measure it closed, and don't forget to include its jump rings or loops. If buying a clasp, the website should tell you its total length.


I did some in-between calculations too.

If the comfortable circumference as measured by your tape measure is 6.75", then the finished length will be 8.11" or 20.6 cm.
17 pearls = 18.7 cm, leaving only 1.9 cm for clasp etc.
16 pearls = 17.6 cm leaving 3cm for clasp etc.

If the comfortable circumference is 6.25", then the finished bracelet will be 7.6" or 19.3 cm.
16 pearls = 17.6 cm leaving only 1.7 cm for clasp, knots and gimp— too small IMO
15 pearls = 16.5cm, allowing 2.8cm for a large clasp

If the comfortable circumference is 5.75" then finished bracelet length is 7.1” or 18cm.
14 pearls = 15.4 cm, allowing 2.6 cm or just over an inch for clasp etc.
15 pearls = 16.5 cm allowing only 1.5 cm for clasp etc.


One big caveat:
Pearls are not made in factories. They may not be exactly 11mm. Allow for variation. If the ones you actually buy are mostly smaller than 11mm, buy an extra pearl, or get a larger clasp. If they are mostly larger, you may need one less pearl, or a smaller clasp. If some are smaller and some are larger, it will probably be a wash.

Edit:

Oops, just noticed a math error, will repost with math corrections if it's too late to edit this.

 

[pearlsngems]

In case it's too hard to picture, I offer this terrible piece of art :

 

[Ann]

In case it's too hard to picture, I offer this terrible piece of art :

I am blown away! You have no idea how much I've been agonizing over this issue, haha! I knew I would never figure it out. So my measurements are 5 3/4 snug and 6 1/4 loose at the point I'd like to wear it. Of course I have to make a final decision on the pearl mm. That could be 10 or 11mm - depending on cost. I have not settled on a clasp - I'm still looking. Probably something simple or maybe a pierced round ball. Is 14kt ok for that or should I use 18 kt. ? Yellow gold of course. Any sources you guys can share? I've looked a bit on Etsy and saw a few that would work. But I want options, don't we all.

 

[pearlsngems]

Hang on I just noticed a math error which I will fix ASAP.

 

[pearlsngems]

The error I made was adding the radius of 2 pearls to the radius of the "comfortable length circle". I ought to have added the radius of just one pearl to get the thread circle radius. It threw off the calculations just a little. Oddly enough it took my own drawing to make me realize my error.

For 6.25" and 11mm pearls the finished length is 7.6" / 19.3 cm.
15 pearls will take up 16.5 cm of that, leaving 2.8 cm (a little more than an inch) for clasp, knots and gimp.

For 6.25" and 10 mm pearls, finished length is 7.5" / 19cm.
17 pearls will take up 17mm of that, leaving 2 cm for clasp etc. Or you can leave more room for a larger clasp by using only 16 pearls, leaving 3 cm for the clasp etc.

 

[Ann]

The error I made was adding the radius of 2 pearls to the radius of the "comfortable length circle". I ought to have added the radius of just one pearl to get the thread circle radius. It threw off the calculations just a little. Oddly enough it took my own drawing to make me realize my error.

For 6.25" and 11mm pearls the finished length is 7.6" / 19.3 cm.
15 pearls will take up 16.5 cm of that, leaving 2.8 cm (a little more than an inch) for clasp, knots and gimp.

For 6.25" and 10 mm pearls, finished length is 7.5" / 19cm.
17 pearls will take up 17mm of that, leaving 2 cm for clasp etc. Or you can leave more room for a larger clasp by using only 16 pearls, leaving 3 cm for the clasp etc.

Thank you! Your calculations no doubt will save me much angst! Your post should be a "sticky". PS members are incredibly gracious and helpful - !!!

 

[Ann]

Ok, I have another question. Should my clasp be similar in size to the pearls? So far, I like a YG round ball clasp. Should that clasp be 10-11mm? Now to source it, haha.

 

[pearlsngems]

For the sake of others who may read the thread, I'm just going to post the minor corrections for the math in posts 5 and 8 above, using the radius of only one of the 11mm pearls to calculate the thread circle radius. (It is too late to edit the posts themselves.)
These calculations are solely for 11 mm pearls.

7" comfortable tape measure length -- finished bracelet length is 8.4" / 21.2 cm.
17 pearls take up 18.7 cm, leaving 2.53 cm (about 1 inch) for clasp, gimp, knots.

6.75" comfortable tape measure length -- finished bracelet length 8.11" / 20.6 cm.
17 pearls = 18.7 cm, leaving only 1.9 cm for clasp etc.
16 pearls = 17.6 cm leaving 3cm for clasp, knots and gimp.

6.5" comfortable tape measure length - finished bracelet length is 7.86" / 20 cm.
16 pearls = 17.6 cm leaving 2.4 cm for clasp etc.
15 pearls = 16.5 cm leaving 3.5 cm for a larger clasp plus gimp and knots.

6.25" comfortable tape measure length - finished bracelet length is 7.6" / 19.3 cm.
15 pearls = 16.5 cm, leaving 2.8 cm (a little more than an inch) for clasp, knots and gimp.

6" comfortable tape measure length -- finished bracelet length is 7.36" / 18.7 cm
15 pearls = 16.5 cm leaving 2.2 cm for clasp, knots, gimp
14 pearls = 15.4 cm leaving 3.3 cm for a large clasp plus gimp and knots


I'll stop there, but if anyone needs more of an explanation, just ask.

I've noticed many people like to use the "orbit clasps" a.k.a. oval push clasps (as Rio Grande calls them) for bracelets. These are longer than many other clasps and a bracelet made with them would require fewer pearls.

 

[dk168]

Ok, I have another question. Should my clasp be similar in size to the pearls? So far, I like a YG round ball clasp. Should that clasp be 10-11mm? Now to source it, haha.

IMHO, the clasp should be as close to the size of the pearls, and I would probably opt for a 10mm rather than 12mm from this site: Bella Findings Ball Clasps.

DK

 

[Ann]

IMHO, the clasp should be as close to the size of the pearls, and I would probably opt for a 10mm rather than 12mm from this site: Bella Findings Ball Clasps.

DK

Thank you! headed there now.

 

[pearlsngems]

Ok, I have another question. Should my clasp be similar in size to the pearls? So far, I like a YG round ball clasp. Should that clasp be 10-11mm? Now to source it, haha.

Can you work a ball clasp with one hand? I don't do that very well; I prefer box clasps with a safety latch.

The problem with ball type clasps is that they are hollow, and bracelets get banged around more than, say, necklaces. You may end up with dents in the ball.

 

[Ann]

Can you work a ball clasp with one hand? I don't do that very well; I prefer box clasps with a safety latch.

The problem with ball type clasps is that they are hollow, and bracelets get banged around more than, say, necklaces. You may end up with dents in the ball.

I think I can but I will definitely look at easier options. Thank you for all your input, it is very much appreciated.

 

[dk168]

Can you work a ball clasp with one hand? I don't do that very well; I prefer box clasps with a safety latch.

The problem with ball type clasps is that they are hollow, and bracelets get banged around more than, say, necklaces. You may end up with dents in the ball.

I thought about that after re-reading your last post about a push clasp.

I never had a full pearl bracelet with a ball clasp, therefore I would not be able to comment.

My 2 pearl bracelets are made of pearl dangles from a chain that I wire-wrapped myself, with large lobster clasps. The chain, pin head wires, split rings and clasps were all from Bella Findings, and they have many pearl clasps on sale.

DK

 

[Ann]

I thought about that after re-reading your last post about a push clasp.

I never had a full pearl bracelet with a ball clasp, therefore I would not be able to comment.

My 2 pearl bracelets are made of pearl dangles from a chain that I wire-wrapped myself, with large lobster clasps. The chain, pin head wires, split rings and clasps were all from Bella Findings, and they have many pearl clasps on sale.

DK

I don't have a problem with Lobster clasps. But I would like something a little more decorative, ya know like pave diamond. I wish!!

 

[dk168]

I don't have a problem with Lobster clasps. But I would like something a little more decorative, ya know like pave diamond. I wish!!

I just check on PP's website, and some of their bracelets have ball clasps on them.

Bella Findings has some more decorative round clasps that you may like.

And yes, I too would love to have a paved diamond ball clasp one day!

DK

 

[Daisys and Diamonds]

In case it's too hard to picture, I offer this terrible piece of art :

Now that's the kind of calculation i can follow !

 

[yssie]

6" comfortable tape measure length -- finished bracelet length is 7.36" / 18.7 cm
15 pearls = 16.5 cm leaving 2.2 cm for clasp, knots, gimp
14 pearls = 15.4 cm leaving 3.3 cm for a large clasp plus gimp and knots

I have a 5.7” wrist, and my mum has a 6.5” wrist, and these calcs are dead on for both of us!! We both use ball clasps

 

[pearlsngems]

Aargh, even my diagram is wrong. I marked the diameter as the radius.

I'm going to make a nicer diagram and label everything right and then make a very concise set of instructions to be used for any round pearl bracelet in which all the pearls are the same size.

 

[pearlsngems]

Here goes. And if anyone does not know how to get radius from c = 2πr, then remember r = c ÷ 2π.
And 2π is 6.28
2 x 3.14 is 6.28
sorry for all the edits! I kept getting an emoji instead of the number 8.

 

[pearlsngems]

I will add: make sure you are working entirely in inches or entirely in cm or mm, or else your results will not work out right.


You can google conversion tools to convert inches to centimeters or millimeters, and vice versa, but 1 inch = 2.54 cm.

 

[MakingTheGrade]

Some math teacher somewhere is smiling and going “remember when you were wondering when you’d ever need to use this?..”

 

[pearlsngems]

If making a bracelet from pearls that are longer than they are wide, like ovals or drops, you have to use the short radius (perpendicular to the thread) as Pearl Radius A to calculate Thread Radius C.

But then you have to use the long diameter in step 5 to calculate how many pearls.

 

[Daisys and Diamonds]

My head hurts