14 Compact Rulers That Fit a Pen Case: What Each One Does Best

Introduction

If you carry a pen case, a 15cm ruler is one of those small tools that quietly earns its place. This roundup covers fourteen compact rulers that fit a standard pen case, all seen as real, owned items rather than catalog listings. Each one has a distinct personality: wood, aluminum, stainless, carbon, leather, even a folding design. Weight, thickness, width, and finish vary a lot, and those differences decide where each ruler belongs in your rotation.

For reference throughout, the Midori Aluminum & Wood Ruler weighs about 12.6g and is used as the baseline for size and weight comparisons.

The Classic: Midori Aluminum & Wood Ruler

The Midori Aluminum & Wood Ruler costs 550 yen tax included, with a 40 yen price increase back in March 2024. It comes in around six colors; three are covered here. The black version uses domestic Japanese bamboo, and natural grain means every piece looks slightly different, which adds a sense of uniqueness and makes picking one in a shop genuinely fun. The pale tan version uses European beech and pairs well with white stationery, while the grey version uses African sapele, a color rarely seen on other rulers.

At roughly 12.6g it is thin and light, which is exactly why it anchors this comparison.

The Charmer: Vintage Wooden Ruler

This vintage-style wooden ruler is an OEM product sold by many makers, with prices ranging from about 320 to 700 yen. It develops character and patina with use, which is part of the appeal. One caveat: touching it releases the distinctive smell of wood, so that is worth knowing before buying.

It is slightly longer and slightly narrower than the Midori, and noticeably heavier at 22.6g. Paired with wood-cased pencils, it makes a lot of sense.

The Design Piece: Tsutol to-Rib by Ihexe Toru Ruler

At 2,530 yen tax included, this ruler comes from a popular stationery shop in Taiwan. The material is a new recycled, non-toxic, odorless wall-set material that feels smooth and resin-like. The brown version has a distinct pattern and a very grown-up, handsome look, with rounded corners that feel good in the hand.

It measures up to 13cm, so it is slim and short. Despite feeling thick at 2mm, that matches the thickest part of the Midori. Weight is just 5g, which is extremely light.

The Practical Pick: Raymay Fujii Easy-to-Read Black & White Ruler

At 220 yen, the Raymay Easy-to-Read ruler comes in black and white colorways, plus 10cm and 30cm lengths. The strong contrast makes markings and text easy to read, and arrows printed on the body show exactly where a line starts, which is genuinely convenient.

It matches the Midori in length but is wide at 2.6cm, so it fits better in a pen case’s zip pocket than in a holder loop. Weight is 9.8g.

The Statement Piece: YS Studio Brushing Ruler

The YS Studio Brushing Ruler costs 3,740 yen tax included and is a 15cm stainless steel ruler with coating on both faces and a brushed stainless side edge. It looks outstanding and is a personal favorite, but heavy use could chip the coating, so it needs careful handling.

Size is nearly identical to the Midori, and it weighs 26.6g. Paired with all-black or black-toned pens, it looks fantastic.

For Left-Handed Writers: Kyoei Plastic LR Aluminum Ruler

The Kyoei LR Aluminum Ruler, 1,100 yen in silver grey, is designed so both right- and left-handed users can read the scale comfortably. The front face runs the markings left to right, but flip it over and they run right to left. Left-handed tools are still rare, so products like this are welcome.

It is 5mm wider than the Midori, otherwise similar in feel.

The Thin One: Radit Edging Ruler

The Radit Edging Ruler, 1,980 yen, is a stainless ruler in the Edging Dust series, with four designs including this Horizontal version featuring English-language markings. The surface has a matte finish with a deep black treatment.

Two honest cautions: on the unit inspected, the markings were compressed in places and hard to read, and burrs remained on both ends that could nick a finger, so check the item carefully when buying. It is about 3mm wider than the Midori but under 1mm thick, very slim, and weighs 13.5g.

The Loft Exclusive: Radit A6063 Ruler

Also 1,980 yen, this Edging Dust series model is a Loft-limited color. The aluminum face has a powder coating with a silky, dry texture. Underneath, it appears to use the exact same base ruler as the Kyoei LR model above, and it is striking how much a different coating and finish changes the impression.

It is 2mm wider than the Midori and weighs 11.2g.

The Luxury Option: Radit Hybrid Ruler

The Radit Hybrid Ruler comes in two flavors: a leather model at 1,980 yen and a wood model at 2,640 yen. The leather is rare Italian leather from Buttero, using the shoulder portion of steer hide. There are four leather colorways, including Black Camel and Silver Turquoise, and it pairs naturally with leather pens and leather pen cases.

The wood version also has four colorways, including Pale Moon Ebony. Since it is a natural material, every piece of wood differs, and it suits wood-cased pens beautifully. Cleverly, both share the same base ruler, with the leather or wood applied into a recess on the back. Weight is about 12g.

The Smart All-Rounder: Mochimono Pitatto Ruler

At 660 yen, the Mochimono Pitatto Ruler comes in navy and orange and won a Japan Stationery Award in 2015. One side is acrylic and the other aluminum: the acrylic side is transparent, making it easy to see the line you are drawing, while the aluminum side works with a cutter, so the two sides serve different purposes. The center is rubber, gripping paper securely so it does not shift while you work.

It does not fit in a holder, so store it in the zip pocket of your pen case.

The Featherweight: Trytech Carbon Ruler

The Trytech Carbon Ruler, 1,590 yen, uses ultra-light carbon with roughly ten times the strength of steel. It is a genuinely easy ruler to use and a daily favorite.

It is 1.5cm longer than the Midori but 6mm narrower, 1mm thick, and weighs only 3.9g, the lightest in this whole lineup. A perfect ruler for an all-black setup.

The Budget Workhorse: Daiso Stainless Ruler

At 110 yen tax included, the Daiso Stainless Ruler is a very simple 15cm tool that is sturdy and easy to use, with 0.5mm markings up to 5cm. It is about 1.4cm longer than the Midori and under 1mm thick. For plain silver utility, it is hard to beat at this price.

The Widebody: Staedtler Aluminum Ruler

The Staedtler Aluminum Ruler costs 605 yen tax included. Ordered online, it arrived wider than expected, which is the one surprise worth flagging. The surface feels smooth, and the back has a non-slip strip so lines stay stable while drawing.

Length is nearly the same as the Midori, but the width is nearly double at 3.5cm, and it weighs 24g. Plan on zip-pocket storage rather than a holder slot.

The Space Saver: Kutsuwa Folding Aluminum Ruler

Last up is the Kutsuwa Folding Aluminum Ruler at 825 yen tax included. Release the lock, extend it, and it becomes a 30cm ruler, which is a clever trick for a pen case tool. The finish is matte and smooth, and it includes a guide that lets you tear paper cleanly along a line at an angle.

Like the Staedtler, it is wide, 1cm wider than the Midori, so a roomy zip pocket is the best home for it. It is also the heaviest here at 40g.

Buying Advice

A few patterns emerge from this lineup. If weight matters most, the Trytech Carbon at 3.9g and the Tsutol to-Rib at 5g are in a class of their own. If texture and character matter, the Midori and the Radit Hybrid are the natural choices. For pure practicality on a small budget, the Raymay and Daiso rulers deliver far more than their prices suggest. And if you need versatility, the Pitatto’s transparent and cutter-ready dual sides, or the Kutsuwa’s folding 30cm reach, cover use cases the others cannot.

One storage note applies across the board: wide rulers like the Staedtler, Kutsuwa, Raymay, and Pitatto fit best in a pen case’s zip pocket rather than a pen holder loop, so check your case layout before choosing.

Conclusion

Fourteen rulers, fourteen different answers to the same question. Swapping them to match your mood or the contents of your pen case is part of the fun of stationery, and hopefully this comparison helps you narrow down which one belongs in yours.