Moving Box Calculator

Background.

Most people run short of boxes twice during a move: once in the kitchen, where dishes, glasses and pans use up small boxes far faster than expected, and again at the very end, when the last drawers and shelves still need emptying. Buying the right mix up front starts with volume. Estimate how many cubic feet of belongings will go into boxes, allow for the space that packing never fills, divide that capacity among small, medium and large boxes, and round each count up, because boxes are bought whole.

The allowance is the packing efficiency. Boxes hold voids around irregular shapes, paper or towels around anything fragile, and the space deliberately left empty in a box of books so that someone can still lift it. At 85% efficiency every 100 cubic feet of belongings needs about 117.65 cubic feet of box capacity, so 180 cubic feet of belongings calls for about 211.76.

The mix matters as much as the total. Books, dishes, tools and files belong in small boxes because weight becomes the problem before space runs out; bedding, pillows, lampshades and other light, bulky things suit large ones. That is why the volume is split by percentage rather than divided by one average box size: 30% to small, 50% to medium and 20% to large in the worked example. Wardrobe boxes, dish packs, picture and TV boxes are a separate decision driven by particular items rather than by volume.

Box capacity is internal length × width × height. Measured in inches, it converts at 1,728 cubic inches to the cubic foot, the relationship given in NIST's unit tables, so a box 18 × 18 × 16 inches inside holds exactly 3 cubic feet and one 18 × 18 × 24 inches holds 4.5. ASTM D5118 describes such fiberboard boxes as packages that unitize and protect their contents through handling, shipping and storage.

Two things sit outside the count. Safe lifting depends on weight, posture and reach, and NIOSH's revised lifting equation starts from 51 lb (23 kg) as the most it recommends even under ideal conditions; a half-full box of books can pass that. And an interstate move in the United States brings FMCSA rules on estimates, liability and paperwork that no box tally can settle.

What is moving box calculator?

Moving box estimation converts the volume of belongings into box counts by size. Belongings volume is the estimated cubic space occupied by items that will be boxed. Box volume is the internal capacity of a box, usually measured in cubic feet or calculated from internal inches. Packing efficiency is the percentage of nominal box space that can realistically be used after allowing for voids, padding, irregular objects, and weight limits. Allocation share is the fraction of the total packing volume assigned to small, medium, and large boxes.

The method suits ordinary household or small office packing estimates. It does not know the exact contents of every room unless you provide inventory details. It also does not decide safe lifting weight, mover tariffs, shipment valuation, damage liability, or truck size. The output is a purchasing estimate for empty boxes and basic budget planning. Specialty containers are counted separately because wardrobes, mirrors, framed art, dishes, computers, and TVs often need boxes whose purpose is protection rather than maximum cubic capacity.

For best results, keep dense, fragile, and specialty items separate from the blended volume estimate, because protection and safe handling often determine the box type before volume does.

How to use this calculator.

1. 01Estimate total belongings volume in cubic feet from an inventory, a previous move or measurement. Shelves are a quick check: a bookcase 3 ft wide, 1 ft deep and 6 ft tall holds at most 18 cubic feet of contents, and a previous move's box count multiplied by the box sizes gives a figure from real experience.
2. 02Enter a packing efficiency. 80% to 90% suits ordinary mixed household goods; go lower for a kitchen full of glassware or a garage of awkward tools, since the field accepts anything from 30% to 100%.
3. 03Enter internal volumes for small, medium and large boxes, from the product label or by measuring inside: length × width × height in inches, divided by 1,728.
4. 04Set the share of volume for each size so that the three percentages total exactly 100; a size set to 0% gets no boxes. Shift share towards small boxes if the household has many books, records or files.
5. 05Count wardrobe, dish-pack, picture and TV boxes item by item, separately from the volume estimate, and enter their count and cost.
6. 06Review total boxes, size counts and estimated cost, then adjust the assumptions for heavy or fragile rooms and run them again.

The formula.

The formula begins with rectangular volume. If a box's internal dimensions are given in inches, multiply length by width by height to get cubic inches. Divide by 1,728 to convert cubic inches to cubic feet because one cubic foot contains 12 inches by 12 inches by 12 inches. If a product label already gives cubic feet, use that directly. Internal dimensions are preferred over outside dimensions because cardboard thickness and flaps do not hold belongings.

Belongings volume is then adjusted for packing efficiency. A theoretical solid fill would use 100% of box space, but household goods are irregular. A lamp base, casserole dish, shoe, framed item, or stack of folded clothes leaves voids. Fragile items need padding. Heavy items should not fill large boxes completely. If E is packing efficiency as a decimal, required nominal box capacity is V ÷ E, where V is the belongings volume. With 85% efficiency, 180 cubic feet becomes 211.764706 cubic feet. Lower efficiency means more boxes.

The adjusted volume is allocated by box size. If small boxes receive 30% of volume, medium boxes 50%, and large boxes 20%, multiply the adjusted volume by 0.30, 0.50, and 0.20. Each size is then divided by its box volume. Because a fractional box cannot be purchased or packed, each count is rounded upward independently. Rounding independently is important. If small boxes calculate to 42.35, you need 43 small boxes. The leftover capacity in small boxes cannot always replace a missing medium box because the items assigned to each size differ by weight and shape. Each size's rounding adds less than one box, so the three together add fewer than three boxes to the fractional total.

Cost is a simple quantity times unit price calculation for each size, plus the specialty-box cost. Specialty boxes are fixed counts because their use is driven by item type rather than blended volume. The formula estimates container count, not safe load weight, mover quotes, insurance valuation, or packing labour. Manual handling risk depends on weight, posture, reach, lift frequency, and other factors outside the volume model.

A worked example.

Frequently asked questions.

References& sources.

1. [1]ASTM International (2025). "ASTM D5118/D5118M-22: Standard Practice for Fabrication of Fiberboard Shipping Boxes." ASTM.
2. [2]Federal Motor Carrier Safety Administration (2024). "Consumer Rights and Responsibilities." U.S. Department of Transportation.
3. [3]Federal Motor Carrier Safety Administration (2023). "Rights and Responsibilities Booklet." U.S. Department of Transportation.
4. [4]National Institute for Occupational Safety and Health (2021). "Applications Manual for the Revised NIOSH Lifting Equation." CDC/NIOSH Publication No. 94-110.
5. [5]National Institute of Standards and Technology (2026). "NIST Handbook 133, Appendix E: General Tables of Units of Measurement." U.S. Department of Commerce.