A katana, a wakizashi, and a tanto can share a curve, a single edge, and a place in the sash, and still be three different weapons. The split is the straight-line length of the blade, the way each one was worn, and the work it was for.
Shop sets like to space three blades into big, medium, and small. The historical lines fall at 1 shaku and at about 2 shaku. A few millimetres past a line changes the name, the draw, and whether the blade can be the companion sword in a pair.
Length bands, in shaku
A shaku is a Japanese unit of length. For swords the figure used on measurement sheets is about 30.3 cm (the Japanese Sword Index gives 30.30 cm, and 10 sun to the shaku, with 1 sun at 3.03 cm). Two shaku is about 60.6 cm. Collectors sometimes round that to 12 inches a shaku. The centimetre figure is the one that matches the bands below.
Blade length, nagasa, is a straight line from the notch on the back of the blade, where the tang begins, to the tip. The nakago is the tang, the unsharpened extension that sits inside the handle, and it is measured on its own. Nagasa does not follow the curve. The parts page on sword anatomynames that notch and the tip if you want the vocabulary. Museums that print "without tang" are giving you nagasa. If a card gives one length and never says whether the tang is in it, treat the number as incomplete until another record says so.
The katana, wakizashi, and tanto pages on this site use the same split in round centimetres: over about 60, about 30 to 60, and under about 30. The shaku figures explain where those round numbers come from.
Four British Museum records show the bands with real objects. A 15th-century Gassan katana blade is listed at 75.5 cm. Divided by 30.3, that is about 2.5 shaku. The record does not add the words "without tang" the way the shorter blades do. Even if 75.5 cm were a little generous, it would stay well over 60.6. An 1850 wakizashi by Yokoyama Sukenaga is 45.6 cm without the tang, about 1.5 shaku, with 1.6 cm of curvature. A Kunishige tanto of the 18th or 19th century is 22.9 cm without the tang, about 0.76 shaku, with 0.3 cm of curvature. A Sukesada tanto dated 1562 is 21.3 cm without the tang, about 0.7 shaku.
Curvature on those cards is the depth of the bow, how far the back stands off the straight line, not a length you add to nagasa. The Sukenaga wakizashi bows 1.6 cm. The Kunishige tanto bows 0.3 cm. A tape laid along the edge still reads longer than the straight line, and a blade near 2 shaku can change bands if you follow the curve. Curve does not pick the name. A nearly straight 22.9 cm blade is a tanto. A curved 45.6 cm blade is a wakizashi.
A longer blade changes the draw, the reach, and whether it can be the companion sword. A tip that has to travel about 75 cm out of the scabbard needs a clear path. A 23 cm dagger comes out in a short pull with one hand. The cut lands farther out as nagasa grows, so the katana is the sidearm for open ground. Only the band between 1 and 2 shaku is the wakizashi, the short half of the Edo pair. Under 1 shaku the blade is a dagger. Over about 2 shaku it is the long sword, the other half of that pair.
Daisho, and the tanto mix-up
Daisho means large and small. In the Edo period it is the matched pair of a katana (or uchigatana) and a wakizashi, worn together at the waist by a samurai. Uchigatana names the edge-up waist mount. The long sword in that mount is what English usually calls a katana once the blade is over about 2 shaku.
That is the mix-up. A dagger is older as a sidearm, and a photo of a long blade plus a short blade looks like a daisho. Under about 30.3 cm the short piece is a tanto. Calling it the companion sword skips the length test that makes a wakizashi.
Wikipedia's summary of Tokugawa rules records an edict of 1629 that required the daisho on official duty, and a 1683 limit that kept the pair to the samurai class. For formal dress the shogunate wanted a black scabbard, black cord wrap, and a hilt in white ray skin. In 1871 the requirement to wear the pair was abolished. In 1876 public wearing of swords was banned for most of the population. The bands stayed in use after those dress rules ended.
Length, wear, job, and the usual mix-up
| Blade | Length band | How it was worn | Main job | What a beginner confuses it with |
|---|---|---|---|---|
| Katana (uchigatana when worn edge-up at the waist) | Over about 2 shaku, about 60.6 cm, in a straight line. A 15th-century Gassan blade at the British Museum is listed at 75.5 cm, about 2.5 shaku if you divide by 30.3, so it sits in this band. | Thrust through the obi, edge up, on the left, so the draw can become a cut. Two hands on the handle once the blade is clear. On a formal visit the long sword was the one left at the door. | Primary sidearm of the three: the two-handed cut, and the draw that starts that cut when there is room. Reach is the point of the extra length. | Any curved Japanese sword, including a tachi, which can be just as long but was hung edge down. Length puts a blade in the long-sword band. The mount tells a waist katana from a hanging tachi. |
| Wakizashi | Between 1 and 2 shaku, about 30.3 cm up to about 60.6 cm, straight line. The 1850 Sukenaga wakizashi is 45.6 cm without the tang, about 1.5 shaku. That is the middle of the band, not a short katana. | In the same sash as the long sword, at the waist. It is the blade that stayed worn when the katana was handed over at a castle or palace entrance. | Shorter partner and backup. Indoors it is the sword you can still draw. In later custom it was also one of the blades used for seppuku. | A small katana, or a long tanto. A nickname such as o-tanto for a blade a little over 1 shaku does not move the band. Past 1 shaku, this classification calls it a wakizashi. |
| Tanto | Under 1 shaku, about 30.3 cm, straight line. A Kunishige tanto is 22.9 cm without the tang (about 0.76 shaku). A 1562 Sukesada blade is 21.3 cm without the tang. Both stay under the line. | In the sash as a one-hand dagger. Some thick armour-piercing examples were worn at the back or on the right, for the left hand. That is a dagger habit, separate from the daisho pair. | One-handed dagger. In earlier centuries, utility and, in the thick yoroi-doshi form, a thrust against armour. Later, often a dress blade. The length class does not change with that shift. | The short half of a daisho. A tanto can sit beside a long sword, and older pairs were often built that way. It is not automatically the wakizashi slot, because that slot starts at 1 shaku. |
| Daisho (the pair, not a third length) | No single band. It needs a long sword over about 2 shaku and a wakizashi between 1 and 2. A dagger under 1 shaku does not complete this pair by being the smaller object in the case. | Both at the waist in the Edo period. Matched mounts were common. At the door, the long sword was left and the wakizashi went inside. | A regulated pair for a samurai on duty, and a large sword plus a small sword when a fight started. Rank and wear are the point of having two, on top of the backup role. | Any two swords photographed together, or a katana sold beside a tanto. Matching lacquer shows a set of fittings. It does not rename a 23 cm dagger into a wakizashi. |
How the three were worn
All three sat in the obi, the sash, which belongs with the rest of dress on the samurai clothing page. The edge faces up on the waist katana, so the draw and the cut can be one motion. The wakizashi occupies the same sash, beside the long sword. A tanto is a one-hand grip in that sash. An aikuchi mount, with no hand guard, is common on daggers and turns up on some short swords. The missing guard is a clue. The centimetre figure still decides the name.
- The katana in uchigatana mount is edge-up through the sash, left side, handle long enough for two hands after the blade clears. On the road it is the sword you expect to draw if there is room.
- The wakizashi rides with it. At a castle or palace door it is the one that stays on the body. Sato's custom, as the Wikipedia wakizashi and daisho pages give it, is to leave the katana at the door and keep wearing the short sword inside.
- A tanto is one-handed. The thick form called a yoroi-doshi was for a thrust in armour. Wikipedia's yoroi-doshi page describes that dagger worn at the back or on the right, drawn with the left hand. That arrangement belongs to the dagger. It does not put the blade in the wakizashi slot of a daisho.
- Matching scabbards mark a daisho. They do not change either nagasa. A black formal pair under Tokugawa dress rules was still a long sword plus a wakizashi.
Indoors, length is a wearing rule with a reason you can see. The Gassan blade at 75.5 cm has to travel most of that distance before the tip leaves the scabbard. A reception room, a corridor, or a man standing close eats that path. The Sukenaga wakizashi at 45.6 cm needs less air. The Kunishige tanto at 22.9 cm is a short draw. The door custom parks the blade whose draw is the awkward one, and leaves the companion sword, the 1 to 2 shaku band, in the sash.
- On official duty outside, wear the pair. Wikipedia's daisho summary cites a 1629 edict that required it.
- At a castle or palace entrance, leave the long sword. The wakizashi stays worn.
- Indoors, the blade you can still draw is the shorter one, between 1 and 2 shaku, about 30.3 to 60.6 cm in a straight line.
- For formal attire the Tokugawa rule was a black scabbard, black wrap, and white ray skin on the hilt. The colours did not replace the length test.
- After the 1876 ban on public wearing for most people, the pair stopped being everyday dress. A 45.6 cm blade was still a wakizashi.
Which blade, in which place
| Situation | Which blade is in the hand | Why that one |
|---|---|---|
| Outdoors, on the road or in a street, with room to draw | The katana, if a blade comes out. The wakizashi stays in the sash until the long sword is lost, stuck, or too slow for the distance. | The long blade is the reach and the two-handed cut. Drawing it needs a clear path for a tip that can be 70 cm or more out of the scabbard. Outdoors, that path exists. |
| Inside a castle or palace, past the entrance | The wakizashi, still worn. The katana has been left at the door with an attendant or set down as the custom required. | Sato, retold on the Wikipedia wakizashi and daisho pages, records that door habit. A shorter blade also clears in a corridor or a reception room where a katana draw would strike a beam, a person, or the ceiling. |
| On the battlefield, once the fight is at sword range | The katana for the two-handed cut and draw. A yoroi-doshi only if the fight has collapsed into a grapple in armour. The wakizashi is the backup if the long sword is gone. | Among these three, the katana is the primary sidearm. The thick tanto is a one-hand thrust, a different job from the long cut. Spears, bows, and guns sit outside this comparison. The katana page covers what an army actually carried. |
| Worn as a matched pair, not yet in a fight | Neither, until something happens. Both the katana and the wakizashi are in the sash. The hand that matters first is the one that parks the long sword at a door. | Daisho means the pair. One draw does not turn the other blade into a spare katana. The indoor rule keeps the wakizashi on the body because it is the companion sword, in the 1 to 2 shaku band. |
What each one was for
The katana is the primary sidearm: a two-handed cut, and a draw that can start that cut when the edge is up in the sash. The extra length is reach. A long draw is awkward indoors. That is the reason for the door habit. Spears, bows, and guns, and the question of what an army carried, sit on the katana page.
The wakizashi is the short sword of the pair. It is the backup when the long sword is unavailable, and it is the sword still worn once the katana has been left at the entrance. In later custom the wakizashi was one of the blades used for seppuku.
The tanto is a one-handed dagger. Early on it was a utility blade and a sidearm, including the armour-piercing yoroi-doshi. Yoroi-doshi means armour piercer: a tanto with a thick spine, built to stab in a grapple. The edge can still cut. The point of the thickness is the thrust. The British Museum's note on the 1562 Sukesada blade, 21.3 cm without the tang, describes a thick triangular section and uses that name. Later centuries often carried the tanto as a dress blade. The Kunishige piece at 22.9 cm is a length on the catalogue card. Both objects are under 1 shaku. Thickness and date change the job. They do not move the band.
How to tell them apart in a photo
Use the label's length first. Handle, curve, and matching lacquer are hints you check after the number.
- Step 1: Find the length on the label — Look for centimetres, and for the words "without tang" or a shaku figure. That is nagasa, a straight line from the back notch to the tip. Skip any second number that is only the tang, and do not add the curvature figure to the length. Curvature is the depth of the bow.
- Step 2: Turn centimetres into shaku — Divide by about 30.3. The Sukenaga wakizashi at 45.6 cm is about 1.5 shaku. The Kunishige tanto at 22.9 cm is about 0.76. The Gassan katana at 75.5 cm is about 2.5. If the card already prints shaku, sun, and bu, 10 sun make a shaku and each sun is about 3.03 cm.
- Step 3: Put the number on a band — Over about 2 shaku, about 60.6 cm, is the katana band. Between 1 and 2 shaku is the wakizashi. Under 1 shaku, about 30.3 cm, is the tanto. A blade within a few millimetres of 2 shaku is the disputed notch. Say so, instead of forcing a nickname.
- Step 4: Read the handle and the mount after the number — A long wrap for two hands fits a katana. A one-hand grip fits a tanto. The wakizashi falls between, and a grip will not settle a blade near the line. Edge-up through a sash is the waist katana. Edge-down hangers point to a tachi, which can be just as long. No hand guard is common on a tanto and does not measure the blade.
- Step 5: Call it a pair only if both blades qualify — Matching lacquer means matched mounts. A daisho still needs a long sword over about 2 shaku and a wakizashi between 1 and 2. If the short blade is 22.9 cm, you have a katana and a tanto, which is an older kind of pairing, not the Edo short-sword slot.
Quiz: katana, wakizashi, and tanto
1. The 1850 Sukenaga blade at the British Museum is 45.6 cm without the tang. Which band is that?
- A. Tanto, under 1 shaku
- B. Wakizashi, between 1 and 2 shaku
- C. Katana, over about 2 shaku
- D. Daisho, because a signed blade is a pair
Show answer
Answer: B. Wakizashi, between 1 and 2 shaku
45.6 divided by 30.3 is about 1.5 shaku. That is the short-sword band. A daisho is two swords worn together, not a length and not a signature.
2. Nagasa leaves out which part of the sword?
- A. The nakago, the tang under the handle
- B. The tip of the blade
- C. The entire cutting edge
- D. The curve only, while the tang is included
Show answer
Answer: A. The nakago, the tang under the handle
Measure a straight line from the back notch to the tip. The tang is recorded separately. A tape along the curve is a longer number than nagasa.
3. In the door custom Sato describes, what stays worn inside a castle or palace?
- A. Both swords, so rank stays visible
- B. The katana, with the wakizashi left outside
- C. The wakizashi
- D. Only a yoroi-doshi
Show answer
Answer: C. The wakizashi
The long sword was left at the door. The wakizashi stayed in the sash. The companion sword had to be short enough to wear and draw indoors.
4. A Kunishige blade at the British Museum is 22.9 cm without the tang, with 0.3 cm of curvature. What is it?
- A. A wakizashi, because it has some curve
- B. A katana with a short handle
- C. The short half of a daisho by default
- D. A tanto, under 1 shaku
Show answer
Answer: D. A tanto, under 1 shaku
22.9 cm is about 0.76 shaku. Curve does not promote it into the wakizashi band. A tanto beside a long sword is still a dagger.
5. What does a change in length change, among these three?
- A. The steel recipe, which is fixed by the name
- B. Draw clearance, reach, and whether it counts as the companion sword
- C. Only the colour of the scabbard
- D. A rule that both blades must be by one smith
Show answer
Answer: B. Draw clearance, reach, and whether it counts as the companion sword
Past about 2 shaku the blade is the long sword. Between 1 and 2 shaku it can be the wakizashi. Under 1 shaku it is a dagger. Matched smiths were not required for a daisho.
Frequently asked questions
- What is a shaku?
- A Japanese unit of length. On sword cards the shaku is about 30.3 cm, and it splits into 10 sun of about 3.03 cm. Two shaku is about 60.6 cm. Those figures come from the kane-jaku used for blades, not from a tape run along the curve.
- How is Japanese blade length measured?
- In a straight line from the notch on the back, where the tang starts, to the tip. That length is nagasa. It leaves out the nakago, the tang hidden in the handle. A tape following the curve reads longer, and a blade near 60 cm can land in the wrong band if you measure it that way.
- What is a daisho?
- The matched pair worn at the waist in the Edo period: a long sword, a katana or uchigatana, with a wakizashi. The name means large and small. Matched mounts were the usual idea. Blades by the same smith were uncommon and were not required.
- What was a yoroi-doshi?
- A thick tanto made to pierce armour. The British Museum record for a Sukesada blade dated 1562, 21.3 cm without the tang, calls the thick triangular section a yoroi-doshi and glosses it as an armour piercer. The length is still under 1 shaku, so the name of the class stays tanto.
- What changes when the blade is longer?
- The draw needs more clear space, the cut reaches farther, and the blade can leave the companion-sword band. Over about 2 shaku it is the long sword. Between 1 and 2 shaku it can be the wakizashi. Under 1 shaku it is a dagger.
- Was the wakizashi used for seppuku?
- In later custom the wakizashi was one of the blades used in that rite. Which blade appears in a given account varies, and the rite is a separate subject from length and wear.
People also ask
- How do the katana, wakizashi, and tanto differ?
- By straight-line blade length, by how they were worn, and by the job. Over about 2 shaku (about 60.6 cm) is the katana band. Between 1 and 2 shaku is the wakizashi. Under 1 shaku (about 30.3 cm) is the tanto.
- Is a tanto the short half of a daisho?
- Not by default. A tanto is a dagger under about 1 shaku, and it is older as a sidearm beside a long sword. The short half of the Edo pair is the wakizashi, between 1 and 2 shaku. A short blade in a photo still needs that length test.
- Which sword stayed on the belt indoors?
- The wakizashi. Kanzan Sato, as the Wikipedia accounts of the wakizashi and the daisho retell him, describes leaving the katana at the door of a castle or palace and continuing to wear the wakizashi inside.
- Can matching fittings replace a measurement?
- No. A daisho often has matched mounts, and that shows a pair, not a length. Two scabbards in the same lacquer still need two straight-line measurements before you call one a katana and the other a wakizashi.
Leave the long sword at the door
The wearing rule that lines up with the measurement is the one Kanzan Sato recorded, as the Wikipedia pages on the wakizashi and the daisho still tell it. At the door of a castle or palace the katana was left behind, and the wakizashi stayed in the sash. The blade that stayed had to sit between 1 and 2 shaku, about 30.3 to 60.6 cm in a straight line, tang excluded. A tanto under 1 shaku, about 30.3 cm, could be on a belt too. It did not take that short-sword place by being smaller.