A bookcase can look full long before you have run out of useful space. The books you reread may be behind a row of books you meant to give away. A tall shelf might hold paperbacks while a nearby shelf squeezes several larger books onto their sides. The one empty space may be at a height you rarely reach. Before buying more shelves, spend an evening seeing how the existing ones serve the collection. Start with the books you reached for this month and the ones you had trouble finding.
Put a few recent books on the table
Find five to ten books you have read, used for a reference, borrowed, or lent recently. They give you a sample of how the shelf works in practice. A cookbook you check while your hands are busy belongs within easier reach than an old guide you consult once a year. A collection of short stories you lend to friends can share a spot with the other books you recommend. Some books sit together because you use them together, regardless of their subject or size. Let that use guide the first group.
Remember the titles you looked for and failed to find. Perhaps a favorite book is on the shelf with a different set of books by the same author. Perhaps its spine is too narrow to spot between larger volumes. One or two retrieval problems can reveal more than a general feeling that the shelf looks busy. Make those titles easy to locate before doing any more sorting. If you share the bookcase, ask the other person what they had trouble finding. Their answer may point to a corner you rarely use.
Find which shelves actually fit the books
Measure the clear height under the shelf above and the depth from the front edge to the back panel. Compare those numbers with the largest books you want to keep upright. Include a little room to lift a book past the shelf above it. The height printed on a bookcase listing often describes the whole unit, while the useful height changes with shelf placement. If the shelves are adjustable, look at the manufacturer's instructions and support limits before changing their position. Empty the shelf you are moving and any neighboring shelf the instructions say to clear.
A little more room at one height can free up several other places. Suppose one tall shelf has a row of short books, while a row of broad art books lies in a heap on another shelf. Try putting the short books together where they can stand with a small gap above them. Place the tall books on a shelf deep enough to support them. Open one of those books at a nearby table to check that you can take it down and put it back comfortably. Store heavy volumes toward the lower part of a stable unit and follow the manufacturer's anchoring and loading instructions.
Choose an order somebody else could learn
Alphabetical order is useful when you look for books by author. A broad subject grouping works when you remember the topic before the name. A shelf by project can help when you frequently take down several titles together. Consider a household with books about drawing, color, typography, and architecture. Some people will use four separate subject groups. A person who keeps turning to the same five books for a weekly sketch session may want those five together. Give the most frequently used groups a straightforward name you can remember without a label.
When the same book could live in two places, choose the place you look first. A biography of an architect may make sense among biographies or design books. Repeatedly moving it according to whichever category seems more precise will make it harder to find. Choose one primary home and keep it there. For a collection large enough to justify a simple index, add a shelf name to a list you already use. You can also place a small card at a likely second location when several people use the shelf. You need only a few such reminders for the books that repeatedly disappear.
Give books in transit their own spot
A library book, an unread gift, and a book waiting for a friend to collect can spend weeks in the wrong row. Their presence makes the shelf less predictable. Give books in transit one short section or a tray sturdy enough for their weight. Keep a library book in view if it has a return date. Put books you are lending together with a slip bearing the borrower's name if that helps you remember. Once something leaves, leave the space open for the next book that needs it.
Limit the area to the number of books you realistically pick up in a few weeks. A large pile of unread books turns into another permanent collection. When it gets crowded, choose which titles you still want within reach and return the others to their subject groups. One row of current reading can fit near a chair, or at eye level if the bookcase is elsewhere. Avoid storing a drink or a vase where moving a book can tip it. The active shelf works best when every book can come off it with one hand free.
Use the back of a deep shelf carefully
Two rows can look efficient on a shelf deeper than the books. The rear row also becomes difficult to see and harder to clean. If you need to use the depth, reserve the back for a clearly identified set you rarely access. A set of old annuals can live behind a visibly distinct front group if you know exactly where they are. Check that pulling one front book out does not bring an unstable row forward. A second row tends to work poorly for books you want to browse by spine.
Sometimes the extra depth is better left empty. Pull the front row far enough forward to read the spines without letting the books overhang. Keep a modest gap behind the books if it helps with cleaning or with passing a hand behind a short volume. On a shelf you frequently use, test taking out a book from the middle and returning it without shifting the rest of the group. If an oversize book needs to lie flat, leave the stack short and keep its cover fully supported. Retrieve it from the stack without bending the covers of the other books.
Make the open spaces part of the arrangement
Leave some room between the groups you expect to grow. The next book by a favorite author is easier to shelve if there is already a gap nearby. A bookend can keep a partial row upright. Choose one that stays put when you slide a book out and that fits without narrowing the gap where your fingers need to go. A light decorative object can work beside a row if it stands securely and is easy to move when you need more room. Keep fragile objects away from the working edge of the shelf.
Decide what you want to see when you enter the room. An open shelf with a few recognizable spines can look settled without having every group filled to its limit. If you like displaying a cover face out, place it where it does not hide a row you use. Leave taller objects where they will not get bumped by a book coming off the shelf. When open space looks awkward at first, live with it for a few days. It may already be doing useful work by making it easier to browse, set something down briefly, or return a book after reading.
Dust is easier to remove when a cloth can reach the exposed edge of the shelf. After clearing a row, wipe the shelf according to its finish and let it dry before you return the books. Look at the window while you decide which books to put back there. If direct sunlight falls across the same spines for much of the day, use a different spot for the copies whose covers you most want to preserve. A nearby shaded shelf may be convenient enough.
Keep the books you can still use or want to keep
A book can be worth a place because you love it, use it, or have a connection to it. Give yourself time to decide when the reason is less clear. A small, dated box for undecided books lets you see whether you look for anything in it. Put it somewhere dry and easy to reach. When you next review it, find out what your local library, shop, or donation center accepts before taking a large load. Some accept only books in certain conditions or kinds of material. Recycle worn volumes if your local service takes the material.
At the end, return five books to the shelf and ask whether you can picture where each one belongs. Walk past the shelf during a normal evening and retrieve the book you were most likely to forget. If you can see it, lift it out, and put it back without thinking hard about the arrangement, the system is doing its job. Revisit the spaces for returning books when they fill. The rest of the shelf can change slowly as your reading changes.
