How to Solve Zip: The Path That Fills Every Cell

Updated June 2026

Zip asks for one continuous line that starts at 1, passes the numbers in order, and fills every single cell exactly once. It feels open-ended, but it is really a chain of forced moves hiding behind a few free-looking ones. Learn where the line has no choice and the rest falls into place.

Two rules do all the work

The line moves one step at a time — up, down, left, or right — and it can never cross itself or re-enter a used cell. Combined with "every cell must be filled," those constraints mean most of the grid is more determined than it looks. The skill is spotting which links are already forced before you commit to the open middle.

Start at the corners and edges

A corner cell touches only two neighbours, so the path must enter through one and leave through the other — both of its links are fixed before you draw anything. Edge cells can never turn outward, which often pins their direction too. Pencil these forced segments in your mind first; they form a skeleton that the interior has to connect to, and they routinely settle whole rows along the border.

Plan the legs between numbers

Treat the numbers as fixed milestones and think one leg at a time: the stretch from 3 to 4, say, must be travelled using only unused cells and without touching 5 or higher yet. Count the cells in that region. If a pocket of cells can only be entered and left during the 3-to-4 leg, that whole pocket must be swallowed on that leg — otherwise it will be stranded once you move past 4 and can never come back.

Keep the unused region connected

The deadly mistake is sealing off an island. Every few steps, glance at the cells you have not used yet: if your line has walled a group off so the remaining path can never reach it, you are already lost — you just do not know it until the end. Because the grid must be filled completely, a single orphaned cell fails the whole attempt. The fix is to keep the empty area as one connected blob and only ever pinch it where you are sure the path returns.

Watch for parity and dead ends

If a cell ever has only one unused neighbour and it is not where the line currently ends, it is a future dead end — the path must pass through it now or it becomes unreachable. Spotting these "about to be stranded" cells early tells you which way to route long before the line gets there. On larger grids, this single check prevents most failed solves.

Work the frame, then thread the middle

Put it together as a rhythm: lock the forced corner and edge links, fix the legs whose pockets must be eaten in order, keep the unused region connected, and only then weave the open centre — which by that point usually has just one sensible route left. When you are racing the clock, this order is also the fastest, because it replaces trial-and-error with a sequence of certainties.

A practical plan

1. Fix the forced links at corners and edges first.
2. Solve leg by leg between consecutive numbers; respect the order strictly.
3. Swallow any pocket that can only be reached on the current leg.
4. Keep the unused cells connected; never wall off an island.
5. Route through soon-to-be-stranded cells before they become dead ends.

Zip rewards looking before you drag. Read the forced structure first and the line almost draws itself — one clean, satisfying stroke that fills the board.