Frequently asked questions

Yes. Every calculator, converter, checklist and guide on this site is free, with no account, no trial and no limit on how many times you run one. Some links to tools and materials earn us a small commission, and there is a disclosure wherever that applies. It never changes a result: the arithmetic is the same whether you buy anything or not.

No, and you do not need to create one to use anything here: every calculator, converter, checklist and guide works without signing in. An account is for the editorial side and for the few features that need to know who you are — saved tools, and comments on a site that has them switched on. Registering gets you those; it is not a gate on the tools, which are open to everyone. Nothing you type into a calculator is stored: the calculation runs in the request and the result lives in the URL, so you can bookmark it or send it to yourself. Page views are counted in aggregate, with no personal data attached.

They are arithmetic on the numbers you enter, so the answer is only ever as good as your measurements. Where a figure is a rule of thumb rather than a measurement — a waste allowance, a coverage estimate, a typical load — the tool says so and shows the range it came from. Measure twice, check the material in front of you, and treat the result as the amount to buy rather than the amount to cut.

Each field shows its unit, and the tools that need one have a selector for inches and feet or centimetres and metres. Pick one system and stay in it for the whole calculation — mixing systems inside a single sum is the most common reason a result looks wrong. Most tools convert internally and report the answer in both, so you can work in whichever one you actually measure in.

Because the thing you are buying is sold in whole units. You cannot buy 3.4 boards, 2.7 sheets of plywood or 4.2 skeins, so the result is rounded up to something you can order. It is rounded after the waste allowance is added, not before, which is the difference between a calculation that looks tidier and one that gets you through the project.

It is the extra you buy so that offcuts, defects, miscuts and pattern matching do not send you back to the shop. Around 10 percent is a fair figure for a straight, plain layout; go to 15 or 20 percent when there are diagonals, awkward perimeters, a one-way print or a repeat that has to match. Buying one spare from the same batch costs less than a second trip.

Yes, if the colour matters. Yarn and fabric are dyed in batches, and a skein from a later batch will not match one you bought six months ago — the difference is often invisible in the shop and obvious on the finished piece. One spare skein or half a metre kept back with the washing instructions turns a repair into a five-minute job instead of a remake.

Yes. Every calculator has an embed page at /calculators/{slug}/embed with a copy-and-paste iframe snippet, a choice of heights and a live preview. The widget carries no cookies and no tracking into your page, and it asks you to keep the attribution link back to the original calculator, which is what keeps the tool free.

Use the contact page and tell us which calculator, what you entered and what you expected. Copying the URL is the most useful thing you can do, because the inputs are carried in the query string — a link reproduces the exact calculation. Corrections to arithmetic, wording or a units conversion are all welcome, and so is a tool you needed and could not find.

Almost always gauge. Stitches and rows per 10 cm (4 in) decide the finished size, and a small difference compounds: half a stitch per 10 cm across a sweater back is several centimetres. Work a swatch, wash and block it the way you will the finished piece, and change hook or needle until the swatch matches the pattern. Then use that gauge in the calculator.

Start from the quantity the pattern states, rounded up to whole skeins, and add one. Two things move that figure: substituting the yarn changes the length you need for the same weight and gauge (a chainette and a plied yarn of the same gauge do not take the same yardage), and any change to length, sleeve or neckline changes it again. If the pattern gives metres and the shop sells 100 g skeins, convert using the skein length printed on the ball band rather than assuming a weight-to-length ratio.

Because the width of the fabric decides how many pieces fit side by side, and that decides how much length you need. Apparel fabric is usually 44/45 in or 58/60 in wide, quilting cotton is normally 44/45 in, and wide quilt backing runs to about 108 in. The same dress takes noticeably less length off a wide bolt, so a yardage figure without a width attached to it is not a usable number.

Enter finished measurements and let the tool add the allowance. 5/8 in (about 1.6 cm) is the commercial pattern standard; 1/4 in is normal for quilt piecing and for seams you will overlock. If you enter cut sizes instead and the tool adds an allowance on top, every piece comes out too big — which is the kind of error you only notice after cutting.

A unit of volume, not of length: 144 cubic inches, which is a piece 1 in thick, 12 in wide and 12 in long. The trade formula is thickness (in) × width (in) × length (ft) ÷ 12, using the nominal sizes the timber is sold by. That is why a price per board foot cannot be compared with a price per linear foot — one measures the wood, the other measures the length of board you carry out of the yard.

Because 2x4 is the nominal size: the name it is sold under, before it is dried and surfaced. A kiln-dried, surfaced 2x4 measures roughly 1½ in by 3½ in. Ordering and pricing use the nominal name, while anything that has to fit — coverage, volume, board feet, a cut list — has to use the dressed size. The board feet calculator asks for both and tells you which one it used for which figure.

The load is a percentage of the wax weight, not of the finished candle, which is why adding the oil makes the fragrance a slightly smaller share of the finished product than the number suggests. Ranges commonly quoted are about 6–10 percent for soy and soy blends, 3–10 for paraffin, 5–10 for coconut, 4–8 for palm and 3–6 for beeswax; 6 percent is a sensible first test. Your supplier's data sheet and a small test batch beat any table, including this one.

Because the right wick depends on the wax, the container diameter, the fragrance load and the dye all at once, and those interact. Burn a test candle all the way down and watch three things: the melt pool should reach the edge within a few hours, the flame should stay steady rather than tall and smoking, and the container should stay comfortable to hold. Tunnelling is a wick that is too small; a container that gets too hot is a safety problem, not a cosmetic one, and it needs a different wick or a smaller diameter.

The safety habits are not optional: sodium hydroxide (lye) is caustic. Add the lye to the water, never water to lye, work somewhere ventilated, wear eye protection and gloves, and keep children and pets out of the room while you work. Use a tested recipe and check it through a lye calculator rather than scaling one by eye, weigh everything including the water, and let the bars cure before you judge them — a soap that seems soft on day two is often fine on day thirty.

Because epoxy cures by a chemical reaction between the two parts rather than by drying. If the ratio is wrong, the leftovers stay tacky, a thick pour can stay soft in the middle, and waiting longer does not fix it. Mix by weight if your kit lists weights, measure into a clean container, mix thoroughly including the sides and the bottom, and only mix as much as you can place within the working time.

Add up four things: the materials you actually used (not the whole skein if you used half), your time at a rate you would accept for the work, your overheads, and the fees the place you sell through takes. Then add the profit you want, and only then ask whether the market will bear the total. If it will not, change the design, the materials or the batch size — dropping your labour to zero is the one adjustment that guarantees the work cannot continue.

Included, and by division rather than addition, because the fee is taken out of what the buyer pays. If the fee is 10 percent and you want to keep 40, the price is 40 ÷ 0.9, which is 44.44 — not 44. The shortcut of adding the percentage looks almost right and quietly loses money, and the gap widens with every fee above about 10 percent. The pricing calculators do the division for you; this is the arithmetic they are doing.

Margin is profit divided by the selling price; markup is profit divided by what the item cost you. The same percentage therefore produces two different prices: a 50 percent markup on an item costing 20 gives a price of 30, and that price is a 33 percent margin. It matters because retailers and wholesale buyers negotiate in margin, while makers often quote markup, and a conversation where the two sides mean different things ends badly.

That depends on where you are, where your buyers are and how much you sell, and it is not a question this site can answer for you. Registration thresholds, what counts as taxable, and whether a marketplace collects on your behalf all vary by country and change from year to year. Check your local tax authority or an accountant before you set prices — getting it wrong is more expensive than the hour it takes to ask.

Use your own times rather than a table: note how long the last three similar projects actually took, then add a contingency for the parts people forget — finishing, drying, curing, blocking, and the second trip to the shop. A project that is 90 percent done still needs the last 10 percent of the time, and that is where hand-made deadlines are lost. The project time tools start from your own figures rather than guessing average ones.