The Binding of Isaac Wiki

Number One is a passive item.

A drop of urine, with light reflecting in it.


Makes Isaac appear happy and smiling while yellow colored projectiles (pee) come from his lower body rather than his face.

Massively increases Isaac's tears by 1.5, but heavily reduces his Range by 13.


  • Any Range stat increasing items (Mom's Underwear for example), will help you regain range lost from picking up Number One.
  • If you have Number One and you have not yet entered The Womb, all Range Down Pills will be converted into Range Up Pills. Note that they do become Range Down again once you enter The Womb.


  • Cancer - Breaks the default Rate Of Fire cap, giving Isaac a very high fire rate.
  • Technology - Technology has infinite range, and thus Number one solely increases the fire rate.
    • Technology + Polyphemus - Polyphemus causes a low firing rate, but number one cancel it and Technology is not affected by range.
  • Brimstone - The charge time of the beam is decreased, with no real downside, since the beam has infinite range.
  • Mom's Knife - Stacks.
  • Dr. Fetus - Stacks.
  • IPECAC - Stacks. The decreased range can be considered a plus, as it makes IPECAC shots easier to aim, while still having enough range to not hit Isaac.
  • The Mulligan - The high fire rate allows the player to spawn many more Attack Flies.
  • Tough Love - The high fire rate allows the player to spawn many more teeth.
  • Mom's Contacts - Some of the tears paralyze enemies, and since there are so many tears, a great number of them will be paralyzing.


  • "Number one" is an informal term for urination, often used when speaking with children.
Passive Items
The Sad OnionThe Inner EyeSpoon BenderMax's HeadMy ReflectionNumber OneBlood of the MartyrBrother BobbySkatoleCube of Meat

Halo Of Flies1UPMagic MushroomThe VirusRoid RageLess Than ThreeRaw LiverSkeleton KeyA DollarA Quarter

Boom!TranscendenceThe CompassLunchDinnerDessertBreakfastRotten MeatWooden SpoonPHD

The BeltMom's UnderwearMom's HeelsMom's LipstickWire Coat HangerRosaryXRay VisionLucky FootCupid's ArrowSteven

PentagramDr. FetusMagnetoTreasure MapMom's EyeDistant AdmirationWiggle WormThe LadderCharm Of The VampireThe Mark

The BatterySteam SaleSister MaggyTechnologyChocolate MilkGrowth HormonesMini MushroomThe PactDead CatLord Of The Pit

Loki's HornsLittle ChubbySpider's BiteSmall RockSpelunker HatSuper BandageSack Of PenniesRobo-BabyLittle C.H.A.D.The Relic

Little GishLittle SteveThe HaloThe Common ColdThe ParasiteMr. MegaThe WaferMoney Equals PowerMom's ContactsGuardian Angel

Demon BabyMom's KnifeOuija Board9 VoltDead BirdBrimstoneBlood BagOdd Mushroom (Thin)Odd Mushroom (Large)Whore Of Babylon

Bobby-BombForever AloneBucket Of LardBomb BagA Lump of Coal

Wrath of the Lamb DLC.png

Guppy's TailStigmataMom's PurseBob's CursePageant BoyScapularSpeed BallBum FriendInfestationIPECAC

Tough LoveThe MulliganTechnology 2Mutant SpiderChemical PeelThe PeeperHabitBloody LustSpirit Of The NightAnkh

Celtic CrossGhost BabyCat-O-Nine-TailsHarlequin BabyEpic FetusPolyphemusDaddy LonglegsSacrificial DaggerMitreRainbow Baby

Stem CellsHoly WaterFateThe Black BeanSacred HeartTooth PicksHoly GrailDead DoveGuppy's Hair BallAbel

SMB Super Fan!Pyro3 Dollar BillMEAT!Magic 8 BallMom's Coin PurseSqueezyJesus JuiceBox
Activated Items
The BibleThe Book of BelialThe NecronomiconThe PoopMr. BoomTammy's HeadMom's BraKamikazeMom's PadBob's Rotten Head

Teleport!My Little UnicornYum HeartDoctor's RemoteShoop Da Whoop!Book Of RevelationsLemon MishapBook of ShadowsAnarchist CookbookThe Hourglass

The NailWe Need To Go Deeper!Deck of CardsMonstro's ToothThe GamekidThe Book Of SinMom's Bottle of PillsThe DiceThe Pinking ShearsThe Bean

Monster ManuelDead Sea ScrollsRazor BladeForget Me NowA Pony

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Guppy's PawIV BagBest FriendRemote DetonatorGuppy's HeadPrayer CardNotched AxeCrystal BallCrack The SkyThe Candle

D20Spider ButtDad's KeyPortable SlotWhite PonyBlood RightsTelepathy for Dummies