Where the size is measured from
Belt sizing confuses people because the number does not describe the object. A belt marked 36 has a distance of 36 inches from the fold at the buckle bar to the centre hole. The leather itself is longer by the fold-back at one end and the holes and tip at the other, and with the defaults on this page that comes to 7.75 inches of overhead: two inches out to the last hole, two and a half more to the tip, and three and a quarter folded back round the buckle.
So there are three different lengths in play and they get mixed up constantly. The size is fold to centre hole. The finished belt is fold to tip, which is what you measure on a belt lying on a bench with the buckle removed. The cut length is the strap you take off the hide, which includes the fold-back you have not folded yet. This page reports all three because the mistake is always a substitution of one for another.
Pant size is not waist size
The usual instruction is to buy a belt two inches above your pant size, and it is a rule of thumb standing in for two separate effects. A belt is worn outside the trousers, over the waistband and whatever is tucked into it, so the circumference it has to travel is genuinely larger. And trouser labelling is not a measurement in any strict sense, so a pair marked 34 may measure anywhere in a range around it.
Which is why the allowance is a field rather than a constant. If you can put a tape around the person, over the clothes they will wear, through the loops, do that and use measured mode. The number you get is the size, with no allowance at all.
Hole spacing and how many
One inch spacing with five holes gives four inches of adjustment, two either side of the size. That covers a good deal of ordinary change in a person and it is why the combination is so common. Wider spacing gives more range from the same number of holes at the cost of coarser adjustment, which matters more than it sounds — three quarters of an inch is the difference between comfortable and not.
Odd counts are worth insisting on for anything you sell. With five holes the middle one is the size, the tag is truthful, and the belt reads as deliberate. With four holes there is no middle, the size falls between two holes, and you have to decide which one to call it. The calculator will lay out an even count if you ask for one and will say what it has done.
| Holes | Spacing | Range | Reads as |
|---|---|---|---|
| 5 | 1 in | 4 in | The ordinary dress belt |
| 7 | 1 in | 6 in | A work belt, or a gift where the size is a guess |
| 5 | 0.75 in | 3 in | Finer adjustment, narrower belts |
| 3 | 1 in | 2 in | A belt made to a measurement, minimal holes |
The keeper, worked from the section
A keeper is a loop that wraps the strap, so its inner perimeter has to clear the strap in section: twice the width plus twice the thickness. The figure on this page adds the keeper leather itself on the turns and whatever overlap you set for the join, because a loop cut to the bare perimeter will not close around the strap it is supposed to slide on.
Cut it long and trim. A keeper that is a quarter inch short is scrap, and a keeper that is a quarter inch long slides, which is what it is for.
Before you cut
The cut length has to exist as one unbroken run in the leather. That is not the same question as whether you have the square footage, and it is where belt projects fail — the hide yield calculator has a straight-run check for exactly this reason. Once the strap is cut and the buckle end is decided, the saddle stitch calculator gives the hole count and thread for the fold-back and the keeper.
Strap cutters and head knives are pulled or pushed with real force through leather that gives way suddenly. The hand steadying the strap is usually in front of the blade.
Questions people ask
How much longer than the waist should I cut the strap?
With the defaults on this page, 7.75 inches: two inches from the size hole out to the last hole, two and a half more from there to the point of the tip, and three and a quarter for the fold-back at the buckle. That is not a constant, though, and the reason it is broken into separate fields is that all three parts move. A larger buckle needs more fold-back. A longer tip is a style decision. More holes push the last hole further out. Change any of those and the overhead changes with it.
Does the fold-back depend on the buckle?
Yes, and it is the number most worth measuring rather than accepting. The leather has to pass the buckle bar, turn back on itself, and lie flat far enough to take a rivet or a line of stitching, with the raw end tucked under the keeper rather than showing past it. A heavy roller buckle on nine ounce leather needs noticeably more than a thin harness buckle on six ounce, because the turn on thick leather has a real radius. Wrap a strip round the actual buckle and measure it.
Where does the keeper sit?
Traditionally right behind the fold-back, so that it holds the tail of the belt and covers the end of the fold. Some belts have a second keeper further along, either fixed or free-sliding, to hold a long tail flat. This page computes the strip length for however many keepers you specify; where they go on the strap is a fitting decision made with the belt assembled, not something to mark out beforehand.
What shape should the tip be?
The calculator takes a straight distance from the last hole to the furthest point of the tip, which is what governs the cut length whatever shape you punch. An English point, a rounded end and a square end all use that same distance measured to the extreme end. Where they differ is how much they leave beside the point, which affects appearance and not length. Set the number to the longest point of the shape you intend and the strap will be long enough for any of them.
Can I use this for a bag strap or a watch strap?
The hole layout and the keeper arithmetic transfer directly, since they are just geometry. What does not transfer is the fold-back, because a bag strap normally has hardware at both ends rather than a buckle at one, and a watch strap is two pieces with the buckle on one of them. For those, work out each piece separately, use the fold-back field for whichever end wraps hardware, and set it to zero for an end that is stitched to a fitting or a ring.