The shoelace length calculator above works out how long a lace has to be for a specific shoe and a specific lacing pattern, from four measurements you can take in a minute: how many eyelet pairs there are, how far apart the two columns sit, how far apart the eyelets are down each side, and how much spare you want at each end for the bow.
Arb Digital builds free calculators that are honest about where the uncertainty lives. On this page it lives almost entirely in that last input. The geometry of the lacing is exact trigonometry; the bow allowance is a preference, and it is typically a third of the whole answer. Any tool that hides it behind a fixed constant is quietly making a decision for you.
What This Shoelace Length Calculator Does
Two patterns are modelled. Criss-cross is the standard method, described on Ian Fieggen's shoe lacing methods reference as the most common and one of the strongest, and it is built from diagonals that each span the full column gap and one vertical spacing. Straight bar lacing produces the horizontal rungs seen on formal shoes: each rung crosses the gap, and the lace travels up the inside of each column between rungs.
The calculator returns the total, splits it into the part consumed by the lacing and the part left for the ends, and shows what the other method would need so you can see the difference before committing. It also converts the answer into the other unit, because laces are sold in inches in some markets and centimetres in others.
How to Use It
- Count the eyelets down one side of the shoe. That count is the number of pairs.
- Do the shoe up the way you normally wear it, then measure straight across between the two eyelet columns.
- Measure the centre-to-centre distance between two adjacent eyelets on one side.
- Decide how much lace you want hanging at each end for the bow, and enter that per side, not the total.
- Read the total, and check the split. If the lacing portion looks right but the total does not, adjust the bow allowance.
The Formula and How It Is Calculated
Take n eyelet pairs, a column gap w, a vertical spacing d and an end allowance E per side.
Criss-cross lacing starts with one horizontal segment across the bottom pair, then climbs with two diagonals for every step up. There are n − 1 steps and two diagonals per step, and each diagonal is the hypotenuse of a right triangle with sides w and d. So:
Criss-cross length = w + 2(n − 1)√(w² + d²) + 2E
Straight bar lacing has one horizontal rung at every pair, so n rungs of w, plus vertical travel of d for each of the n − 1 steps on each of the two sides:
Straight bar length = nw + 2(n − 1)d + 2E
Work the defaults. Seven pairs, a 2 inch gap, 1 inch spacing and 7 inches per end. Each diagonal is √(2² + 1²) = √5 = 2.2361 inches. There are 2 × 6 = 12 of them, giving 26.83 inches, plus the 2 inch bottom segment and 14 inches of ends: 42.83 inches, or 108.8 cm. The same shoe laced straight bar needs 7 × 2 + 12 × 1 + 14 = 40.00 inches, about 2.8 inches less.
That figure is a reasonable cross-check against the eyelet-count table in the general reference on shoelaces, which gives roughly 100 cm for a six-hole shoe and scales up from there. Where your answer diverges from a table like that, the reason is almost always the end allowance rather than the geometry.
Why the Bow Allowance Dominates
On the defaults, 14 of the 42.83 inches — a third of the lace — is the two ends. Halving the allowance to 3.5 inches a side drops the requirement to 35.83 inches, which is a completely different lace. No amount of care measuring the eyelets matters next to that.
The practical consequence is that a single shoe has no single correct lace length, only a range set by how you like to tie it. If you tie a large double bow, or use a knot that consumes more lace, you want the upper end. If you tuck the ends or tie tightly, the lower end. Buying at the long end is the safer error: a lace that is slightly long can be tied out, while one that is short cannot be stretched.
There is one exception worth knowing. Very long laces on shoes with few eyelets end up dragging, which is a trip hazard on anything with a heel and a real annoyance on trainers. If the calculated length is far above what the shoe came with, check the end allowance before assuming the original lace was wrong.
Why Criss-Cross Needs More Lace Than Straight Bar
It comes down to the diagonals. Each criss-cross diagonal is √(w² + d²), which is always longer than the w a horizontal rung uses, and criss-cross uses two of them per step against straight bar's one rung plus two short verticals.
How much longer depends on the shape of the shoe. On a shoe where the eyelets are tightly spaced relative to the gap — small d, large w — the diagonal is barely longer than the horizontal and the two methods converge. On a boot with widely spaced eyelets and a narrow gap, the diagonals are much longer and criss-cross can need noticeably more. Our Pythagorean theorem calculator is the general form of that diagonal, and running a few values through it makes the relationship obvious quickly.
This is also why swapping methods on an existing lace often fails. Re-lacing a criss-cross shoe as straight bar leaves you with too much lace and an oversized bow; going the other way frequently leaves you short at the top, which is the version people notice.
Measuring the Gap Correctly
The column gap is the input people get wrong, because it is not a fixed property of the shoe. It is however wide the shoe sits when you wear it. Measuring a shoe lying open on a table can easily double the figure, and since the gap appears in every diagonal, doubling it inflates the whole lacing portion.
Do the shoe up first, then measure across between the innermost edges of a middle pair of eyelets. Use a middle pair rather than the top or bottom, because the gap usually tapers, and the middle is the closest thing to an average. If the gap varies a lot from top to bottom, take two measurements and average them; the error that introduces is far smaller than the error from measuring an open shoe.
For the vertical spacing, measure centre to centre between two adjacent eyelets rather than edge to edge, and check that the spacing is even. Some boots space the lower eyelets more tightly than the upper ones, in which case take the average across the whole column.
Converting Between Inch and Centimetre Sizes
Laces are stocked in inches in some markets and centimetres in others, and the conversion catches people out because the numbers are not round. Forty-five inches is 114.3 cm, not 115, and 120 cm is 47.24 inches. The calculator reports both so you can shop in whichever unit the retailer uses.
If you need to convert other measurements alongside it, our cm to inches converter and length converter handle single values and full unit chains respectively, and the unit converter covers everything else. If you are also buying the shoes rather than just the laces, the shoe size converter moves between US, UK, EU and centimetre sizing.
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Browse the Free Tools Hub Talk to Arb DigitalCommon Mistakes to Avoid
- Measuring the gap on an open shoe. Do the shoe up first. An open shoe can show double the real gap and inflates every diagonal.
- Counting every eyelet as a pair. Fourteen holes is seven pairs. Counting fourteen roughly doubles the lacing portion.
- Entering the bow allowance as a total. The field is per side, so a 7 inch entry adds 14 inches to the result.
- Assuming one length fits both methods. Criss-cross needs more than straight bar on the same shoe, and the gap widens as eyelet spacing grows.
- Buying short to avoid drag. A slightly long lace can be tied out; a short one cannot be fixed at all.
Related Free Tools From Arb Digital
The Pythagorean theorem calculator handles the diagonal at the heart of criss-cross lacing. For units, use the cm to inches converter, the length converter or the general unit converter. If you are sizing the shoes as well as the laces, the shoe size converter covers US, UK, EU and centimetre systems. Everything else is on the free online tools hub.
Frequently Asked Questions
On a typical shoe with a 2 inch gap between the eyelet columns, 1 inch between eyelets and 7 inches spare at each end, criss-cross lacing needs about 42.8 inches, or 109 cm. Straight bar lacing on the same shoe needs about 40 inches.
For criss-cross lacing it is the column gap, plus twice the number of steps multiplied by the square root of the gap squared plus the eyelet spacing squared, plus twice the end allowance. Each diagonal is the hypotenuse of a triangle with the gap and the spacing as its sides.
Because every diagonal is longer than the horizontal distance it covers, and criss-cross uses two diagonals per step. Straight bar uses one horizontal rung plus two short vertical runs, which together are shorter unless the eyelets are very widely spaced.
It is entirely a preference and the calculator takes it as an input. Around seven inches a side gives a comfortable standard bow, four gives a tight one, and it typically accounts for about a third of the total length, so it matters more than any other input.
Pairs. Count the holes down one side only. A shoe with fourteen holes altogether has seven pairs, and entering fourteen would roughly double the calculated lacing.
Do the shoe up the way you normally wear it, then measure straight across between a middle pair of eyelets. Measuring a shoe lying open can easily double the figure, and since the gap appears in every diagonal it distorts the whole result.
Slightly long. Extra length can be absorbed in a larger bow or a different knot, while a lace that is too short cannot be fixed. The exception is very long laces on low-eyelet shoes, which drag and become a trip hazard.
Multiply inches by 2.54. The calculator shows both units at once, so 45 inches appears as 114.3 cm rather than a rounded 115, which matters when a retailer stocks fixed sizes.
This page is a geometry tool. It computes lace length from the measurements you enter, and the end allowance is a preference rather than a specification, so treat the result as a target rather than an exact requirement. Manufacturers' stocked lengths vary, and buying slightly long is the safer error.
