Binding of Isaac: Rebirth Wiki

Number One is a passive item.

Effects[ | ]

  • +1.5 tears.
  • (except in Repentance) -17.62 range.
  • (in Repentance) -1.5 range and -20% range multiplier. Will not decrease range below 4.00.
  • (except in Repentance) +0.76 tear falling speed.
  • Tears turn yellow and are fired from Isaac's lower body rather than his head.

Notes[ | ]

  • Number One doesn't increase the tear rate cap, meaning picking it up with tears capped (normally 5.0) will just decrease range with no benefit.
  • (in Repentance) Multiple copies of Number One, (such as those made by (except in Rebirth)Collectible Diplopia iconDiplopia), will not cause the negative range multiplier to stack.

Synergies[ | ]

  • (in Repentance)Collectible Abyss iconAbyss: When Isaac uses Abyss to absorb Number One it turns into a yellow locust that is faster, deals damage quicker, but has a limited range.
  • Collectible Brimstone iconBrimstone / (in Repentance) Character Tainted Azazel iconTainted Azazel: The laser turns yellow and charges at a much faster rate with no decrease to the range.
  • Collectible Epic Fetus iconEpic Fetus: Increases fire-rate with no decrease in range. Explosive clouds are now yellow.
  • (in Afterbirth and Afterbirth †)Collectible Incubus iconIncubus: The Incubus fires at a much faster rate with no decrease to the range.
    • (in Repentance): Incubus' range decreases like normal.
  • Collectible The Ludovico Technique iconThe Ludovico Technique: Turns tear yellow and allows it to be moved much faster.
  • Collectible Number One iconNumber One: Gives an additional fire rate bonus without further reducing range.
  • (in Afterbirth † and Repentance)Collectible Pop! iconPop!: Eyeball tears are yellow, can be fired much quicker, and does not affect their airtime.
  • Collectible Technology iconTechnology: The laser turns yellow and Technology's firing rate is greatly increased with no decrease to the range.
  • (except in Rebirth)Collectible Tech X iconTech X: Laser turns yellow, charge time is greatly decreased, and no decrease to the range.
  • Collectible Tiny Planet iconTiny Planet: Tears travel a slightly smaller distance but can be fired much quicker.

Interactions[ | ]

  • Character Azazel iconAzazel: Lowers range, reduces charge time.
  • (in Afterbirth † and Repentance)Collectible Compound Fracture iconCompound Fracture / Collectible The Parasite iconThe Parasite: Tears often disappear before being able to split. Split tears also only travel a very short distance.
  • Collectible Cricket's Body iconCricket's Body: Tears disappear very quickly after being fired, and split tears barely travel at all.
    • (in Repentance) Not recommended. Number One's x0.8 range multiplier stacks with Cricket's Head's own x0.8 range multiplier, thus drastically reducing range.
  • Collectible Dr. Fetus iconDr. Fetus: Not recommended. Makes bombs travel distance very short. The extremely reduced range can turn simple rooms into a challenge and self-damage a constant concern.
  • (in Afterbirth † and Repentance)Collectible Haemolacria iconHaemolacria: Does not affect the main tear; however, burst tears travel significantly less far.
    • (in Repentance) Not recommended. Number One's x0.8 range multiplier stacks with Haemolacria's own x0.8 range multiplier, thus drastically reducing range.
  • Collectible Ipecac iconIpecac: Increases fire rate moderately, and decreases range only slightly.
    • (in Repentance) Not recommended. Number One's x0.8 range multiplier does stack with Ipecac's own x0.8 range multiplier, making self-damage more likely.
  • (except in Rebirth)Collectible Kidney Stone iconKidney Stone: The stone is not affected by short range, otherwise the combo behaves as expected. (except in Repentance) Number One's range penalty overrides Kidney Stone's.
  • Collectible A Lump of Coal iconA Lump of Coal: Tears still increase in size and damage as they travel; however, the short-ranged distance limits tear size and damage.
  • (except in Rebirth)Collectible Marked iconMarked: Tears become orange. The firing rate is increased, Marked's effect is unaffected but the range is reduced.
  • Collectible Mom's Knife iconMom's Knife: The knife turns yellow and the maximum range is significantly reduced.
  • (except in Repentance) Collectible Monstro's Lung iconMonstro's Lung / (in Afterbirth † and Repentance)Collectible Lead Pencil iconLead Pencil: Not recommended. Tear barrage disappears very close to Isaac.
    • (in Repentance) Range is more forgiving.
  • (except in Repentance)Collectible Proptosis iconProptosis: Not recommended. Tears disappear after traveling a very short distance.
    • (in Repentance) This is now fixed and works as expected.
  • Collectible Rubber Cement iconRubber Cement: Tears often disappear before being able to bounce off walls.
  • Collectible Tooth Picks iconTooth Picks: Tears become orange.

In-game footage[ | ]

Trivia[ | ]

  • "Number One" is a euphemism for urination and mirrors "Number Two" being an euphemism for defecation.
    • This is why the tears fired after collecting this item are no longer fired from the head, but the lower waist.
  • In the original Binding of Isaac, Number One had the effect of turning all future Range Down pills into Range Up pills. This was presumably designed to reduce the risk of players being stuck in situations where their range would become too low to clear certain rooms. However, in Rebirth, Number One no longer has this effect, and will not turn Range Down pills into Range Up pills.
  • This item is used in High Brow (challenge #2).
  • (in Rebirth and Afterbirth) The firing animation of Number One is a little different from what it looks like in the original Binding of Isaac.