How to Cut Soap


The following page is for educational purposes only. Soap by the Loaf now ships your soaps already cut into bars. However, we have left the information below as an archive for anyone wanting to learn about how to cut soap into bars. The below does not apply to your orders from us which are now, as of late 2023, already sliced into bars for you. Thank you.

Your soap arrives to you in whole loaves or entire blocks. It is best to unwrap the loaves and cut them into bars as soon as they arrive. It is much easier for the bars to cure when air can reach the entire surface of the bar. That’s rather hard to do when the bars are still compacted together into one solid loaf.

So, the big questions is – how do I cut soap loaves into bars?

There are many soap cutters out there on the market. The problem is, most of them have to be custom made to fit your particular soap loaf. Most are made with a metal frame and wires stretched at intervals to make the cuts. Some have even made their own cutters using the same method, using guitar wire. For me, stretched wires make me nervous. Ever seen the 1999 movie The Haunted with Liam Neeson, Lili Taylor and Catherine Zeta-Jones? One of the minor characters touches the string on a clavichord (medieval stringed instrument) and the wire snaps and slashes her face. Ouch. I can’t think of soap cutters with wires without seeing that scene in my head. Anyway, these professional soap cutters can cost anywhere from $50 all the way up to $450.

Someone once said your hands are the best tools you have. I found this to be true when it comes to cutting soap into bars, using nothing more than a wooden mitre box and a cutting blade.

For cutting the soap, I use a pastry scraper which is easily found in any kitchen supply store. The wooden handled ones seem to be the best ones to use because they have a longer life and are less likely the bend. The cheaper ones often warp over time with continuous slicing. Pastry scrapers are usually used in the kitchen for picking up foods you have chopped or for lifting fresh dough onto baking pans. They range in price from $6 to $20. Be sure to buy the metal kind as the plastic ones won’t work for cutting soap. You can use a knife but you have to find just the right size. If the knife is too small it won’t slice all the way through the soap, leaving you to have to make a second cut at the bottom. If your knife is too large or too thick, it pushes the soap down as you slice which wastes soap and makes for a messy knife.


The wooden mitre box acts as your guide. Trust me, even the steadiest of hands can cut some really crooked soaps. The straight edge of the box ensures straight cuts every time. The reason why I use a mitre box made of wood is because I can saw into it. Hard plastic ones are too hard to alter. With the wooden mitre box, you can insert a saw into the straight cut and finish sawing the notch all the way down to the base of the mitre box. If you don’t take this step, the blade won’t cut all the way through your soap.

First you have to decide how wide you want your bars of soap to be. Most people choose to cut their soaps into a one inch thickness. At, we cut our soap bars 1.25 inches thick, which gives us 10 bars from a loaf of soap. When you decide your thickness, measure over from the straight cut and make a mark on top of the mitre box to the right of the guide. If you have several thicknesses of bars (such as regular size, guest size, jumbo size) use three different colors of pens to make your mark. It really helps in remembering which cut is which. There’s nothing more frustrating than slicing up and entire loaf of soap – the wrong size!

So, slide the soap loaf into the mitre box from the left and bring the edge of the soap over to the mark you’ve made on the top of the mitre box. Now, take your pastry scraper and start from the back side and begin sliding the blade into the soap loaf in a rocking down motion until the blade falls into the straight groove closest to you. You have now cut your first bar of soap off of your soap loaf. Keep going until you reach the end of the loaf. Sometimes there will be small pieces left at the end of the loaf which are great to keep for yourself.

So, how about how to cut a block of soap into three loaves? More amazing technology is used including a yard stick, a small knife and the pastry scraper. Our soap blocks are nine inches across. Loaves are three inches across. I take the end of the yard stick and rest it against the edge of the soap block. Now, if your block is slightly smaller (sometimes happens) nudge the yard stick a bit to adjust the measurement all the way across the block. What I do now is make a small slit into the block at 3 inches and another one at 6 inches. Then, I do the same thing at the other end of the block. This gives me a guide to then lay the yard stick across the block in the other direction, resting against the slits I’ve made. I then take the knife and run it along the edge of the yard stick, making a small score all the way down the length of the block. Do it again on your 6 inches marks.

Now, with clear lines on my block, I take the pastry scraper and push it all the way down into the soap on my score line. The scraper won’t be long enough to do this in one cut so I lift it out and continue down the block until a loaf of soap is cut away. It’s that simple. A few inexpensive tools and a pair of sturdy hands with cut many bars of soap. I’ve been cutting them this way for over a decade.

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