I'm assuming we're talking about the lug rig here, right?  I could go measure mine and report back, but the best thing might be to stretch the head and foot of your sail out along the yards, assuming you have your sail in hand, to make sure that you have enough length to get a taut stretch between the tack cringle and it's corresponding outhaul cringle along the lower yard (sometimes called the "boom"), and between the throat cringle and the peak outhaul cringle along the upper yard.  You want to make sure you don't cut 'em too short for the sail, or you'll never be able to get good tension on the head and foot to have the sail set properly.  Better too long than too short.

.....Michael

   Thanks for your kind reply, ummm, don't know how to sail yet, ummmm, what's a cringle, and I assume you mean the two sides of the sail (outhaul and tack) and the upper part of the sail (throat and peak)? and yes it's a lug rig

   Sailing does have it's own lingo and it takes some time to get comfortable w it but cringles are the brass reinforced eyes at the corners.  Search on this site for lug rigs and there's a couple of articles to help.  Also read through your manual's later pages for rigging details.  My skerry manual and plans had dimensions for boring the holes in the boom and yard (boom is the lower horizontal spar, yard is the angled upper one) used for lashing on the sail.  So long as you have enough length to accomodate those dimensions, anything more is excess.  You might be able to trim a little off the ends to reduce a bit of weight but I'd wait to do that until you've laid it all out.  Also, you can use a plane or saw to taper the ends of the spars (oh, "spar" is the generic term for any stick of wood used to rig sails) to also save a bit of weight.  Weight up high on a rig is less desirable and the lug rig has more weight in the yard than it really needs.  Again, your manual or plans should show this.

Sorry about the jargon.  Sailors have all of this technical language to avoid confusion...which of course only works if you have the decoder ring.  I forgot myself there.

Here's a link to a photo which may help with the balanced lug terminology:

https://i.pinimg.com/originals/7d/86/f1/7d86f14a1f53080336a1b6b34c160418.jpg

Thanks, Mummichog, for jumping in to help clarify my excessive nauticalisms.

.....Michael

   Thanks for your replies, especially the diagram. Out to the backyard we go to measure

...and, when you're tapering the ends of the spars, to leave the edge where the sail goes untapered, i.e., taper three sides only.  If memory serves, we cut longer tapers  on the after ends than the forward ends--the highest stress on the spars of a balanced lug comes at the halyard and downhaul attachments, so longer tapers on the after ends makes some sense.

.....Michael