Block Perms and Cross-Coupon Grids: An In-Depth Rules Q&A
Perms confuse a lot of newer players, and block perms confuse them twice over. The maths is not actually complicated once you break it down into its separate parts, but the terminology around blocks, anchors, and combined grids tends to get thrown around loosely. This Q&A works through the mechanics properly, with worked figures throughout.
Q: What is a block perm, in plain terms?
A block perm splits your selections into two or more separate groups, or “blocks”, and perms within each block independently before combining every possible line across blocks. It differs from a standard perm, which treats every selection as part of one single pool of matches permed together as a whole.
Q: Why would anyone split selections into blocks rather than just perming everything together?
Cost control is the main reason. Perming a large number of matches together as one group grows very quickly, because the number of lines is governed by the combinations formula C(n,k) — the number of ways to choose k matches from n selections. Splitting into blocks keeps the line count, and therefore the stake, far more manageable while still covering a reasonably wide range of combinations.
Q: Can you show the actual numbers?
Yes — this is where the value of a block perm becomes clear. Suppose you have eleven fixtures you want represented across your slip, and you want any eight of them to be correct draws for a return. Permed as a single group, that is “8 from 11”, calculated as C(11,8):
| Perm type | Formula | Lines |
|---|---|---|
| Straight 8 from 11 | C(11,8) | 165 |
Now split those same eleven fixtures into a block of six and a block of five. Within the block of six, perm any four as correct — C(6,4). Within the block of five, perm any three as correct — C(5,3):
| Block | Formula | Lines |
|---|---|---|
| Block A (4 from 6) | C(6,4) | 15 |
| Block B (3 from 5) | C(5,3) | 10 |
| Combined block perm | 15 × 10 | 150 |
At a stake of an illustrative 10p per line, the straight 165-line perm costs £16.50, while the 150-line block perm costs £15.00. The saving here is modest because the block split was chosen fairly close to the single perm’s size — the gap widens considerably with larger selections, which is the main appeal of blocks for bigger coupons.
Q: Does a block perm cover exactly the same ground as a straight perm of the same size?
No, and this is the most important distinction to understand. A straight 8 from 11 perm covers every possible combination of eight correct draws drawn from all eleven matches, with no restriction on how those eight are distributed. A block perm covering 4 from 6 plus 3 from 5 only pays out on combinations that land exactly four correct within block A and exactly three correct within block B — a combination of five correct in block A and two in block B, even if that totals seven correct draws overall, would not be covered by this particular block structure in the way a straight perm would recognise it.
Why this matters for prize tier coverage
- Straight perms give you broader, more evenly spread coverage across every possible distribution of correct draws.
- Block perms concentrate coverage around a specific expected distribution, which is more cost-efficient if your research genuinely points to that distribution being the likely one.
- Getting the block split wrong — for example, expecting strength concentrated in the wrong block — can leave you with zero return even when you have correctly predicted a strong overall total of draws, simply because they landed in the “wrong” block for your chosen structure.
Q: What is a shared anchor, and how does it interact with blocks?
An anchor is a selection you are highly confident about, included as a certainty across every line of your perm rather than being part of the combinatorial choice. When combined with a block structure, an anchor sits outside both blocks, included in every single line regardless of outcome in the blocks themselves. If you add one anchor match to the 150-line block perm above, you still generate 150 lines — the anchor does not multiply the count, it is simply attached to every line already generated by the blocks.
Q: How many anchors can sensibly be added before it becomes risky?
Technically there is no formal limit, but each anchor is a single point of total failure for every line on your slip. One incorrect anchor result voids the entire perm regardless of how the blocks perform, so anchors should be reserved for selections you would be comfortable including as a genuine certainty, not simply your favourite pick of the week.
A worked summary
Putting it all together: an 11-match slip structured as a 4-from-6 plus 3-from-5 block perm with one separate anchor runs to 150 lines, each line containing the anchor plus one qualifying combination from each block, for a total of twelve matches represented on the coupon. At 10p a line, illustratively, that is a £15 stake covering a specific, cost-controlled slice of the possible outcomes — considerably narrower than a full straight perm across all twelve matches, but far better value than attempting to cover every possibility in full.
Work through the combinations slowly before committing a stake, and if the maths feels uncertain, build a smaller trial perm first to get comfortable with how blocks and anchors interact. As always, treat perm costs as entertainment spending set against a limit decided in advance, and remember participation is restricted to those 18 and over.
Q: How do you decide the right split between blocks in the first place?
This is less a maths question than a research question. The combinations formula tells you exactly how many lines any given split produces, but it cannot tell you whether six strong draw candidates and five weaker ones is a more sensible structure than, say, two even blocks of five and six matches with no particular hierarchy. A reasonable approach is to group your strongest, most-researched selections into the block where you expect the highest proportion of correct draws, since that block effectively becomes the backbone of your coverage, with the second block providing a wider net around less certain fixtures.
It is worth sketching out two or three alternative block structures for the same set of matches before committing, since the line count and cost can shift meaningfully depending on exactly how the groups are sized, even when the total number of matches and the total number of correct draws required stays the same.
Q: Is a block perm ever a worse choice than simply reducing your overall selection count?
Sometimes, yes. If your actual confidence is spread fairly evenly across all eleven matches with no genuine reason to expect a particular distribution of correct draws, a straight perm across a smaller number of your most confident selections can be both cheaper and more honestly aligned with your research than an elaborate block structure built mainly for cost reasons. Blocks earn their complexity when your research genuinely supports treating two groups of matches differently — not simply as a way to make a large coupon artificially cheaper without a clear rationale behind the split.