Pack your ruck
Lay it out, and see what it does to you
Put your gear where it will actually sit and get scored on weight, balance and reach — with the centre of gravity worked out from the real positions, not guessed.
How this works
Why placement matters as much as weight
Two packs with identical contents and identical total weight can feel completely different to carry. A pack's centre of gravity wants to be as close to your own as possible — roughly navel height, near your spine. The further the mass sits from that point, the more leverage it exerts on you.
Mass low in the pack pulls you backwards and down. Mass out at the front pocket levers you backwards. Either way you compensate by leaning forward from the waist, and holding that lean for an hour is where the post-ruck back ache comes from.
How the three scores work
Load asks whether the pack is the weight you meant to carry. Balance asks whether the computed centre of gravity sits inside the band a loaded pack should occupy, and close enough to your back. Reach asks whether the things you might suddenly need — a shell, first aid, food — are somewhere you can get at without unpacking.
They are scored separately because they trade off against each other. Moving a heavy item to the spine helps balance; burying your rain jacket to do it hurts reach. A single number would hide that.
The suggestions are computed, not canned
Every suggested fix is applied to a copy of your loadout and re-scored before it is offered, so the gain shown next to it is the actual change rather than an estimate. A change that would not improve the pack is never suggested.
The reach test
Ask one question of everything you pack: if I need this, will I have to empty the bag to reach it? This is routinely got wrong with the rain shell, and a shell at the bottom of a packed rucksack is a shell you will not put on until you are already wet.
Common questions
How should weight be distributed in a rucksack?
Dense items high and against the back panel, around shoulder-blade height. That keeps the pack's centre of gravity close to your own, which is what stops it levering you backwards and making you lean forward to compensate.
What is a good centre of gravity for a loaded pack?
Roughly 56 to 72% of the pack's internal height above its floor, and within about 9 cm of your back. Lower than that pulls you backwards and down; further out increases the leverage the load exerts on you.
Do I need an account to use this?
No. Your draft and named packs can be saved in this browser, and share links contain the whole pack. Sign in if you want to save packs to your account and attach them to logged rucks.
Are the gear weights accurate?
They are realistic mid-range figures for each item as carried, meant as a sensible starting point rather than a claim about your specific kit. Add your own items with real weights when precision matters.
The reasoning in prose is in how to pack a ruck so it stops pulling you backwards, and what to actually bring is in what to put in your ruck. Choosing the carrying system? Compare a weighted vest with a backpack, then fit it using the loaded adjustment order.