Crypto Unit Converter

Convert between cryptocurrency units instantly. ETH ↔ Wei ↔ Gwei, BTC ↔ Satoshi. All processing is done client-side.

Wei(10⁰ Wei)

Kwei (Babbage)(10³ Wei)

Mwei (Lovelace)(10⁶ Wei)

Gwei (Shannon)(10⁹ Wei)

Microether (Szabo)(10¹² Wei)

Milliether (Finney)(10¹⁵ Wei)

Ether(10¹⁸ Wei)

Ethereum Unit Reference

Unit	Wei Value	Ether Value
Wei	10⁰	10^-18
Kwei (Babbage)	10³	10^-15
Mwei (Lovelace)	10⁶	10^-12
Gwei (Shannon)	10⁹	10^-9
Microether (Szabo)	10¹²	10^-6
Milliether (Finney)	10¹⁵	10^-3
Ether	10¹⁸	10⁰

What the Crypto Unit Converter does

Ethereum stores every balance as an integer count of wei, where 1 ETH = 10^18 wei. Bitcoin stores balances as an integer count of satoshis, where 1 BTC = 10^8 satoshi. These integers are what your wallet, RPC node, and contracts see — the "0.5 ETH" figure in a UI is always derived. Type the wrong number of zeroes and you either fail to send anything at all or accidentally send 1000x what you meant.

Type a value into any field (ETH, wei, gwei, BTC, satoshi, mBTC) and all the other fields update simultaneously using BigInt math. No floating-point rounding, no loss of precision even for values that overflow JavaScript's safe integer range.

This page handles ETH and BTC unit scales. For converting between a token amount and its on-chain integer (a different problem — each ERC-20 has its own decimals()), the Token Decimals Calculator is the right tool.

A scenario that hurts

You are wiring up a script that pays out an airdrop. The off-chain spreadsheet says "send 0.05 ETH to each address." You hard-code 0.05 into the value field of your transaction builder and ship. Twenty minutes later recipients are pinging you because they received 50 wei — about $0.00000000001 of ETH. The transaction did not revert because 0.05 was implicitly converted to 0 (since wei is an integer) or to 50 (if your library happened to multiply by some other factor). Always convert to wei first, then send the integer. That five-second paste into this converter would have flagged the error before the airdrop went out.

How to use the converter

Select the cryptocurrency tab — ETH (Ethereum) or BTC (Bitcoin).
Enter a value in any unit field (e.g., type 1 in the Ether field).
All other unit fields will update instantly with the converted values.
Click the copy button next to any field to grab the value for a script, a contract call, or a gas-cost estimate.
Switch tabs to convert between Ethereum and Bitcoin units. The two scales are independent — there is no cross-currency rate here.

EVM chains covered

Sample inputs that this tool processes correctly. Paste any of these into the editor above to see a valid decode; shapes that do not match these patterns are rejected before any calculation.

Chain / family	Sample	Format
Ethereum	0x742d35Cc6634C0532925a3b844Bc9e7595f8f12a	hex, 20 bytes, EIP-55 checksum
Polygon	0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48	hex, same as Ethereum
Arbitrum	0xB0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48	hex, same as Ethereum

Quick reference: Ethereum unit ladder

Unit	Wei	Common use
wei	1	Native unit on-chain. Every uint256 ETH balance is wei.
kwei (babbage)	10^3	Rarely used; legacy.
mwei (lovelace)	10^6	Used internally by some bridges; otherwise rare.
gwei (shannon)	10^9	Standard unit for gas price and EIP-1559 base fee.
microether (szabo)	10^12	Used by some old DEXs for fee accounting.
milliether (finney)	10^15	Convenient for small swaps; ~$3 at $3k ETH.
ether	10^18	User-facing balance and transaction value.

BTC is simpler: 1 BTC = 10^8 satoshi. mBTC (10^5 satoshi) and bit/μBTC (10^2 satoshi) are display conveniences from the 2013 community RFC, not on-chain units.

Common pitfalls when working with wei and satoshi

Sending an ETH float to a contract. Solidity has no native floats. Your library must convert to wei first; some libraries do this implicitly, some throw. Hard-coding 0.05 sometimes ships as 0, which a node happily accepts and broadcasts.
Off-by-one in zero counts. 10^18 has 18 zeros; gwei is 10^9 (9 zeros); szabo is 10^12. Counting wrong by even one zero produces a number 10x or 0.1x the intended value.
Mixing up gas price and gas cost. Gas price (gwei per unit) times gas used (units) gives the cost in wei. Confusing one for the other is a common reason people quote "30 gwei gas" as if it were the total transaction cost.
Treating wei as a JS Number. Above 2^53 wei (~0.009 ETH), JavaScript loses precision. Use BigInt or a string. The converter here always uses BigInt internally.
Pasting a wei value with thousands separators. Block explorers display 123,456,789,000,000,000 for readability. RPC nodes only accept the plain integer. Strip commas before any contract call.
Confusing BTC mBTC with bit/μBTC.1 mBTC = 0.001 BTC = 100,000 satoshi. 1 bit (sometimes "μBTC") = 0.000001 BTC = 100 satoshi. Off by 1000.

Crypto Unit Converter vs ethers / web3 / Etherscan calculator

This tool: instant browser conversion across all common units. No install, no library imports, no need to remember whether the function is parseUnits, parseEther, or toWei in your current SDK.
ethers.formatUnits / parseUnits: the right answer inside production code. Same math; verify your script's output against this tool when debugging.
Etherscan's unit converter: functionally similar but ETH-only. Skips BTC. Also requires you to leave whatever tab you are working in.
Manual calculator: 1.5 ETH = 1.5 * 10^18 wei. Doable in 30 seconds if you remember the exponent. The converter saves the time and the off-by-one risk.

Real-world integration

Before broadcasting a transaction, paste the valuefield from your wallet preview into this converter as wei, then verify the ETH amount is what you meant. This five-second sanity check catches the "extra zero" or "missing zero" class of mistake that has cost users seven-figure sums on the bidding side of NFT auctions.

When debugging a stuck transaction, the explorer shows gas price in gwei and total gas used as an integer. Multiply manually or use this tool to convert the gwei * gas_used result into ETH terms. Pair with the Wei Converter for quick sanity checks on the same calculation, or use the Solana Lamports Converter for the Solana equivalent.

For ERC-20 tokens, the same logic applies but with each token's own decimals() value (USDC is 6, WBTC is 8, most others 18). Use the Token Decimals Calculator for those — the wei↔ETH conversion only applies to native ETH.

When NOT to use this tool

You need to convert ERC-20 amounts (USDC, USDT, custom tokens). Each token has its own decimals(). Use the Token Decimals Calculator.
You need price conversion between ETH and USD, or BTC and EUR. This tool only does unit conversion within a single asset; you need a price feed for cross-currency.
You need cross-currency conversion (ETH to BTC). Same issue — requires a market exchange rate, not a fixed ratio.
You are doing gas cost estimation. The numbers are right, but you still need gas price + estimated gas used. Use an estimator like Blocknative or your RPC's eth_estimateGas.

Troubleshooting

Large numbers shown in scientific notation in my script: JavaScript renders 1e18 for big numbers by default. The converter always displays the full integer string; use that when copying to your transaction builder.
The result is "0": you probably pasted a fractional ETH value into the wei field. Wei is an integer; fractions truncate to zero. Paste the value into the ETH field instead.
The decimal point disappeared: the converter strips trailing zeros for readability. 1.50000000 ETH shows as 1.5 ETH; the value is identical.
Numbers do not match Etherscan: Etherscan rounds ETH display to 5-6 significant digits. Compare wei to wei (full precision) before assuming a real mismatch.

Key features

BigInt arithmetic preserves precision for the largest wei values, well beyond the JavaScript safe-integer range.
Bidirectional sync: edit any field and the rest update without rounding artifacts.
Covers all seven Ethereum units (wei, kwei, mwei, gwei, szabo, finney, ether) and all four common Bitcoin units (satoshi, bit, mBTC, BTC).
Copy buttons on every field for quick paste into scripts or contract calls.
Tabbed UI keeps ETH and BTC workflows independent so unit-name overlaps cannot confuse the math.
Runs 100% client-side. Values never leave the page.

Frequently asked questions

What is wei and why does Ethereum use it?

Wei is the smallest indivisible unit of ETH: 1 ETH = 10^18 wei. The EVM cannot represent fractional ETH directly — every uint256 balance is a wei count. The 18 decimal places give enough granularity to express both micro-transactions and whale-sized transfers in the same integer. Named after Wei Dai, who proposed b-money in 1998 (a Bitcoin predecessor).

Why are gas prices quoted in gwei?

A typical gas price is 20 gwei (0.00000002 ETH). Writing it in wei would be 20000000000 — hard to read and easy to mis-type. Writing it in ETH hides the magnitude (you would not notice if it jumped from 0.000000020 to 0.000000200). Gwei is the unit at the right scale for the typical range of L1 gas prices.

What is a satoshi and why 100 million per BTC?

A satoshi is the smallest unit of BTC: 1 BTC = 100,000,000 satoshi. Bitcoin Core's codebase stores balances as int64 satoshis, which gives 21 million * 10^8 = 2.1 * 10^15 — comfortably within int64 range. The 8-decimal choice was Nakamoto's; it provides enough granularity for any conceivable transaction size without exotic types.

Is BigInt math really necessary for this?

Yes. 1 ETH = 10^18 wei, but JavaScript's safe integer ceiling is Number.MAX_SAFE_INTEGER = 2^53 - 1 ≈ 9 * 10^15. Any wei value above ~0.009 ETH overflows. BigInt (the native 1n literal) handles arbitrary precision. The converter uses BigInt throughout.

Can I convert between ETH and BTC here?

No. Cross-asset conversion requires a real-time market price, which this tool does not fetch. It only converts between units of the same asset. For ETH↔BTC pricing, check CoinGecko, Binance, or a DEX quote — those are inputs to a price oracle, not a unit converter.

Does this work for L2s like Arbitrum or Base?

Yes. All EVM-compatible chains use the same wei↔ETH scale. ETH on Arbitrum, Optimism, Base, Polygon, BNB Chain, and any other Ethereum-derived chain is 10^18 wei per ETH. Only the gas-pricing structure differs (some L2s expose blob gas separately), not the unit scale.

What about other native tokens (MATIC, BNB)?

MATIC, BNB, AVAX, and most other EVM chain natives also use 18 decimals — same as ETH. So a "wei" of MATIC is 10^-18 MATIC, mathematically identical to ETH wei. The labels say ETH/wei here, but the math is the same for any 18-decimal native.

Related guides

Ethereum for Developers: Addresses, Checksums, and Key Concepts

Everything you need to start shipping on Ethereum: EIP-55 address checksums, wei-to-ether math, gas mechanics, wallet derivation, and the Hardhat vs Foundry split.

Token Decimals and Human Units: Where DeFi Math Quietly Goes Wrong

USDC has 6 decimals, ETH has 18, SOL has 9. The off-by-one decimal bug that bricks a transaction or misprints a balance is one of the most frequent DeFi failures — here is how to think about it.

Related Tools

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Ethereum for Developers: Addresses, Checksums, and Key Concepts12 min read Token Decimals and Human Units: Where DeFi Math Quietly Goes Wrong10 min read

Unit

Wei Value

Ether Value

Wei

10⁰

10^-18

Kwei (Babbage)

10³

10^-15

Mwei (Lovelace)

10⁶

10^-12

Gwei (Shannon)

10⁹

10^-9

Microether (Szabo)

10¹²

10^-6

Milliether (Finney)

10¹⁵

10^-3

Ether

10¹⁸

10⁰