Any 8 From 15: The Maths Behind 6,435 Lines and Fractional Stakes

Ask any experienced coupon player about the “any 8 from 15” permutation and you’ll usually get a slight wince — it is one of the biggest full perms available, and the line count sounds enormous until you see where the number actually comes from. Here is the maths laid out properly, along with what it means once digital platforms let you stake in fractions of a penny per line.

Where 6,435 actually comes from

A permutation like “any 8 from 15” means you have picked 15 matches you fancy as potential score draws, and you want every possible combination of 8 of them covered as a separate line. The number of combinations is given by the standard combinations formula, written as C(15,8), which works out as 15! divided by (8! × 7!).

Running the arithmetic: 15! is a very large number, but it cancels down neatly against 8! and 7!. The simplified calculation is (15 × 14 × 13 × 12 × 11 × 10 × 9) ÷ (7 × 6 × 5 × 4 × 3 × 2 × 1). The top line multiplies out to 32,432,400, and the bottom line (7 factorial) is 5,040. Dividing the two gives exactly 6,435. That is the full line count for this permutation — no more, no less, and it is fixed regardless of which 15 matches you actually chose.

Why the number grows so fast

It helps to see the pattern across smaller versions of the same perm, since the jump in line count as the pool of selections grows is genuinely dramatic:

Each extra match added to your selection pool roughly doubles the line count rather than adding a fixed amount — which is exactly why going from “any 8 from 14” to “any 8 from 15” adds more than 3,400 extra lines in one step.

What this means for your stake, in practice

At a traditional whole-penny-per-line stake, 6,435 lines would mean a genuinely large total outlay — illustratively, at 1p a line that is £64.35 for a single week’s perm, before any multiplier. This is exactly the problem that fractional stakes were built to solve. Modern digital pools platforms allow stakes down to a fraction of a penny per line, for example an illustrative 0.1p or 0.5p per line.

At an illustrative 0.1p per line, the same 6,435-line perm costs 6,435 × £0.001 = £6.435, rounded in practice to the platform’s nearest billing unit. At an illustrative 0.5p per line it becomes 6,435 × £0.005 = £32.175. The structure of the perm — and therefore your coverage of every possible 8-match combination from your chosen 15 — stays identical; only the total cost moves up or down with the fractional stake chosen.

Does the huge coverage actually buy better expected value?

Coverage and expected value are not the same thing, and it’s worth being honest about that distinction. A full “any 8 from 15” perm guarantees that every combination of 8 score draws drawn from your 15 chosen matches is covered by one of your 6,435 lines — so if exactly 8 of your 15 selections land as score draws, you are guaranteed at least one winning maximum-points line. What it does not do is improve the underlying chance that 8 of your particular 15 matches land as score draws in the first place; that probability is set entirely by the actual football, not by how many lines you buy.

In other words, the perm buys certainty of capturing the best outcome available within your chosen matches, not a better outcome than those matches were always going to produce. Whether that trade-off is worth the outlay is a personal judgement about variance and budget, not a maths problem with a single correct answer.

Scaling down: what if 15 selections feels too wide?

Not every player wants to carry a full “any 8 from 15” — the jump from 3,003 lines (any 8 from 14) to 6,435 lines is large enough that many regulars prefer to trim their selection pool by one or two matches rather than stake the full spread. Dropping to “any 8 from 13” cuts the line count to 1,287, less than a fifth of the 15-match version, while still covering every combination within a slightly narrower set of fancied matches. The trade-off is straightforward: fewer matches means less safety net if one of your “fancied” score draws turns out wrong, but a dramatically smaller, more manageable total stake.

Rounding and minimum stake rules matter in practice

The clean arithmetic above assumes a stake that divides perfectly across every line, but real platforms apply their own minimum unit sizes and rounding rules at checkout. A calculated total of, say, £6.435 at an illustrative 0.1p rate will typically be rounded to the platform’s nearest billable amount, and some platforms set a minimum total stake per coupon regardless of how small the per-line fraction works out. Always check the live total shown on your own slip before confirming — the formula tells you the line count and the theoretical cost, but the platform’s own checkout screen is the figure that actually gets charged.

A sensible way to approach it

• Work out the full line count for your chosen perm size before you commit to a stake, using the table above as a quick reference.
• Decide your total weekly budget first, then solve backwards for the fractional stake per line that fits it — rather than picking a stake per line and being surprised by the total.
• Remember that a bigger perm spreads a fixed budget thinner across more lines, which is a trade-off, not automatically an improvement.

Perms like this are a legitimate way to structure a coupon, but the scale of the numbers makes it easy to lose track of real spend. Set your total budget before you start, use the operator’s limit-setting tools, and remember these figures are illustrative only — always check the live stake calculator on your own account before confirming a line. 18+ only.