Step-by-Step: Calculating a Perm 8 From 12 and Its True Line Cost

Perms are the backbone of flexible Treble Chance play, letting you back a wider pool of fixtures than eight without needing to nail all eight outright. The trouble is that the jump from a small perm to a slightly larger one can produce a cost increase that catches out anyone who hasn’t actually worked through the maths themselves. This guide walks through calculating an “8 from 12” perm from first principles, step by step, so the final line count and cost stop feeling like a mysterious number pulled from a table.

Step 1: Understand what the perm is actually asking

An “8 from 12” perm means you have selected 12 fixtures you are reasonably confident about, but rather than committing to one fixed set of exactly eight, you want every possible combination of eight selections drawn from those twelve to count as a separate line. This hedges against getting one, two or three of your twelve picks wrong, since plenty of the generated lines will still contain eight genuinely correct selections even if a few of your twelve overall picks turn out wrong.

Step 2: The combination formula

The number of ways to choose 8 items from a pool of 12, where order does not matter, is given by the combination formula, written C(12,8) or sometimes “12 choose 8”:

C(n,k) = n! / (k! × (n-k)!)

Here, n is your total pool (12 fixtures) and k is how many you need correct (8). The exclamation mark denotes a factorial — the product of every whole number from that number down to 1. So 12! means 12 × 11 × 10 × 9 × 8 × 7 × 6 × 5 × 4 × 3 × 2 × 1.

Step 3: Plugging in the numbers

C(12,8) = 12! / (8! × 4!)

Rather than calculating the full factorials of 12 and 8, which produce enormous numbers, it’s far easier to cancel terms first. Since 12! = 12 × 11 × 10 × 9 × 8!, the 8! in the numerator and denominator cancel out entirely, leaving:

C(12,8) = (12 × 11 × 10 × 9) / 4!

And 4! = 4 × 3 × 2 × 1 = 24. So:

C(12,8) = (12 × 11 × 10 × 9) / 24 = 11,880 / 24 = 495

Your “8 from 12” perm therefore generates exactly 495 individual lines.

Step 4: Working out the actual cost

Once you know the line count, calculating total cost is simple multiplication: lines × unit stake per line. The table below shows this at a few illustrative unit stakes, purely to demonstrate scale — not any official current pricing structure.

This table is precisely why perm size discipline matters so much more than it might first appear — the jump from 2p to 20p per line turns a modest weekly entry into a far more significant one, purely through the multiplication of a fixed, unchanging line count.

Step 5: Comparing neighbouring perm sizes

To see how sensitive perm cost is to small changes in pool size, it’s worth calculating the neighbours of “8 from 12” too. C(10,8) = 45 lines, C(11,8) = 165 lines, C(12,8) = 495 lines, and C(13,8) = 1,287 lines. Moving from a pool of 10 fixtures to a pool of 13 — adding just three extra selections — takes you from 45 lines to 1,287 lines, a near-29-fold increase.

Step 6: Avoiding budget wipeout with fractional staking

Because 495 lines can quickly turn even a small per-line unit stake into a meaningful total, many players use fractional pence stakes specifically to keep a wider perm affordable without abandoning the extra coverage it provides. A fractional stake of, say, half a penny per line turns the same 495-line perm into a £2.475 total commitment rather than £24.75 at a full 5p stake — a tenth of the cost for the exact same coverage and hit structure, simply at a proportionally smaller potential return per correct line.

• Decide your total weekly perm budget first, then work backwards to find the unit stake that fits your chosen pool size, rather than picking a unit stake arbitrarily and discovering the total cost afterwards.
• Use the C(n,8) formula — or a reliable calculator — before finalising your fixture pool, not after, so an unexpected cost jump doesn’t force an awkward last-minute reduction.
• Remember that adding even one or two extra fixtures to your pool can disproportionately increase total lines, exactly as the neighbouring-perm comparison above demonstrates.

Why doing this calculation yourself is worth the effort

Plenty of platforms will calculate perm costs for you automatically, which is convenient day to day. But understanding the underlying combinatorics means you immediately recognise why a seemingly small adjustment to your fixture pool produces a disproportionate cost change, rather than treating the final number as an opaque output from a system you don’t fully trust or understand. That understanding is what lets you make genuinely informed staking decisions rather than reactive ones.

Perms can make the Treble Chance more flexible, but wider pools cost real money fast, as the maths above shows clearly. Decide your budget before building your pool, keep it proportionate to what you can comfortably afford, and remember the pools are entertainment, not an income strategy. You must be 18 or over to play.