BIP 177: Redefine Bitcoin's Base Unit

  BIP: 177
  Title: Redefine Bitcoin's Base Unit
  Author: John Carvalho <bitcoinerrorlog@gmail.com>
  Comments-URI: https://github.com/bitcoin/bips/wiki/Comments:BIP-0177
  Status: Draft
  Type: Informational
  Created: 2025-04-23
  License: CC0-1.0

Introduction

Abstract

This BIP proposes redefining the commonly recognized "bitcoin" unit so that the base unit becomes the primary reference unit. Under this proposal, one bitcoin is defined as that indivisible base unit, eliminating the convention of synthetic decimal places. By making the base unit the standard measure, this BIP aims to simplify user comprehension, reduce confusion, and align on-chain values directly with their displayed representation.

Motivation

The current convention defines one bitcoin as 100,000,000 base units. This representation requires dealing with eight simulated decimal places, which can be confusing and foster the misconception that bitcoin is inherently decimal-based. In reality, Bitcoin’s ledger represents values as integral base units. The decimal point is merely a human-imposed abstraction.

By redefining the base unit as "one bitcoin," this BIP aligns user perception with the protocol’s true nature. It reduces cognitive overhead, ensures users understand Bitcoin as counting discrete units, and ultimately improves educational clarity and user experience.

Specification

Redefinition of the Unit:

Internally, the base units remain unchanged.
Historically, 1 bitcoin = 100,000,000 base units. Under this proposal, "1 bitcoin" equals one base unit.
What was previously referred to as "1 bitcoin" now corresponds to 100 million bitcoins under the new definition.

Terminology:

The informal terms "satoshi" or "sat" are deprecated.
All references, interfaces, and documentation SHOULD refer to the base unit simply as "bitcoin."
The currency code "BTC" is unaffected by these changes, and continues to mean 100,000,000 base units.

Display and Formatting:

Applications SHOULD allow users to toggle between the legacy BTC format (1 BTC = 100,000,000 base units) and the new integral format (1 bitcoin = 1 base unit).
Use of the ₿ symbol MAY be used to represent base-unit bitcoins but is OPTIONAL.

Example 1:

Old display: 0.00010000 bitcoin
New display: ₿10,000 or 10,000 bitcoins or 0.00010000 BTC

Example 2:

Old display: 10.23486 bitcoin
New display: ₿1,023,486,000 or 1,023,486,000 bitcoins or 10.23486 BTC

Example 3:

Old display: 0.345 BTC
New display: No changes required or ₿34,500,000 or 34,500,000 bitcoins

NOTE: Traditional number display abbreviations, like 2.5M for millions, are also optional.

Conversion:

Ledger and consensus rules remain unchanged.
BTC as a currency code remains unchanged (1 BTC = 100,000,000 base units)
Implementations adopting this standard MUST multiply previously displayed bitcoin amounts by 100,000,000 to determine the new integer representation.

Rationale

Usability: Integer-only displays simplify mental arithmetic and reduce potential confusion or user error.

Protocol Alignment: The Bitcoin protocol inherently counts discrete units. Removing the artificial decimal format aligns user perception with Bitcoin’s actual integral design.

Educational Clarity: Presenting integers ensures newcomers do not mistakenly assume that Bitcoin’s nature is decimal-based. It conveys Bitcoin’s true design from the start.

Future-Proofing: Adopting the base unit as the primary measure ensures a consistent standard that can scale smoothly as Bitcoin adoption grows.

Perception of Supply: While the total count of base units is roughly 2.1 quadrillion, this proposal does not alter supply in any way. The change is purely representational. Comparisons can be drawn to other currencies like the Japanese yen or Indonesian rupiah, where high unit counts are standard and not perceived as inflationary.

Addressing Alternative Approaches

Refuting the "Bits" Proposal (BIP 176)

An alternative suggestion (BIP 176) proposes using "bits" to represent one-millionth of a bitcoin (100 satoshis). While this reduces the number of decimal places in certain contexts, it fails to fully address the core issues our BIP aims to solve:

Persistent Decimal Mindset: Using "bits" still retains a layered decimal approach, requiring users to think in terms of multiple denominations (BTC and bits). This shifts complexity rather than eliminating it.
Inconsistent User Experience: Users must learn to toggle between BTC for large amounts and bits for small amounts. Instead of providing a unified view of value, it fragments the user experience.
Incomplete Alignment with the Protocol’s Nature: The "bits" proposal does not realign the displayed value with the integral nature of Bitcoin’s ledger. It continues to rely on fractional units, masking the fundamental integer-based accounting that Bitcoin employs.
Not Permanently Future-Proof: Though "bits" may simplify certain price ranges, future circumstances could demand additional denominations or scaling adjustments. Our integral approach resolves this problem entirely by making the base unit the standard measure, avoiding future fragmentation.

In essence, while BIP 176 attempts to simplify small amount representations, it only replaces one decimal representation with another. By redefining "bitcoin" as the base unit, this BIP eliminates reliance on decimal fractions and separate denominations entirely, offering a clearer, more intuitive, and ultimately more durable solution.

Handling the Terms “satoshi” and “sat”

Background

“Satoshi” (or its shorthand “sat”) emerged organically some years ago, to honour Bitcoin’s creator and to give a friendly name to the 100-millionth "fraction" of a bitcoin.
Over time “stacking sats” became a meme, and the term now appears in podcasts, apparel, and some wallet UIs.

While culturally valuable, the term introduces an implicit second denomination layer that contradicts the goal of this BIP: a single base unit, called simply "bitcoin". Of course this BIP cannot stop anyone from using any colloquial term they prefer, but this document exists to specify how to display Bitcoin's only units as "bitcoin" correctly.

Backward Compatibility

No consensus rules are altered, and on-chain data remains unchanged. Differences arise solely in display formats:

For Developers: Update GUIs, APIs, and documentation to present values as integers. Remove references to fractional Bitcoin. BTC units remain unchanged.
For Users: The actual value of holdings does not change. Transitional measures, such as dual displays or explanatory tooltips, can ease the adjustment period.

Security Considerations

A short-term risk of confusion exists as users adapt to the new representation. Users accustomed to decimals may misinterpret initial displays. To mitigate this:

Offer dual displays and tooltips during the transition.
Provide clear educational materials and coordinated messaging.
Use alerts or confirmations in applications if input values appear unexpectedly large or small.
Highlight the unchanging 21M BTC supply cap and equivalence to avoid misinterpretation as inflationary.

Reference Implementation

Some wallets, such as Bitkit, have successfully adopted integer-only displays, demonstrating the feasibility of this approach, without incident. Transitional features — like showing both old and new formats side-by-side — can help smooth the transition.

Test Vectors

Old: 1.00000000 Bitcoin → New: ₿100,000,000 (or 100,000,000 bitcoins)
Old: 0.00010000 Bitcoin → New: ₿10,000 (or 10,000 bitcoins)
Old: 0.00500000 Bitcoin → New: ₿500,000 (or 500,000 bitcoins)
Old: 0.005 BTC → New: 0.005 BTC (or ₿500,000 or 500,000 bitcoins)

All formerly fractional representations now directly correspond to whole-number multiples of the base unit.

Implementation Timeline

Phase 1 (3-6 months): Introduce the concept, provide dual displays and educational materials. Begin pilot testing in willing wallet apps.

Phase 2 (6-12 months): Prominent services adopt integer-only displays by default. Community coordination and media campaigns ensure consistency.

Phase 3 (12+ months): Integer representation becomes standard. Documentation and user guides no longer reference decimal-based formats.

Conclusion

Redefining "bitcoin" as the smallest indivisible unit, and removing decimal-based representations, simplifies comprehension and aligns displayed values with the protocol’s integral accounting. While a transition period may be necessary, the long-term benefits include clearer communication, reduced confusion, and a more accurate understanding of Bitcoin’s fundamental design.

Copyright

This BIP is licensed under CC0-1.0.