# Ethereum wallet simulator: an ETH screen that reads right

Source: https://flexdger.com/blog/ethereum-wallet-simulator
Updated: 2026-10-16
Published: 2026-10-16
Topic: Crypto wallet mockups (https://flexdger.com/blog/crypto-wallets)

> Composing an Ethereum wallet screen that reads right: ETH units and gwei, a value that tracks the live price, the 0x checksum, gas, and what it never proves.

An ETH screen gets judged on details no Bitcoin or Solana screen carries: eighteen decimals hiding behind what is displayed, fees quoted in gwei, a 0x address whose capitals are a checksum, and dollar stablecoins sitting beside it on six decimals.

**Short answer:** An Ethereum wallet simulator builds an ETH-centred wallet screen out of quantities you supply: each dollar value is that quantity times the current ETH price, and the day’s change follows the market percentage. It reads right only when units, decimals and fees behave the way Ethereum does, and since it joins no chain, the screen is a mockup that proves nobody holds anything.

## First, what a mockup lacks

Put a genuine Ethereum wallet beside a simulated one and four things separate them, none of which a screenshot can fake for long:

- the address opens on a block explorer, with a balance and a history behind it;
- every send leaves a transaction hash that an explorer finds, showing the gas used and the block it landed in;
- the wallet names the network it is showing, since one 0x address exists on every EVM chain;
- each ERC-20 row is read from the token’s own contract, using that contract’s own decimals.

The simulator offers none of those in a form an explorer could confirm. It joins no chain, never requests a private key or a seed phrase, and cannot sign or send anything. What it does is arrange numbers you supply so that the screen reads the way Ethereum screens do. The rest of this page is about getting that reading right.

## Reading a 0x address, capitals included

An address is the characters 0x followed by 40 hexadecimal digits, 42 in total. Since the same string is valid on every EVM chain, it never reveals which network you are on. The capital letters inside it are a checksum, set out in EIP-55 in 2016. To produce it, run the lowercase address through Keccak-256, then capitalize each letter whose matching digit in the hash is 8 or above.

Take the first mixed-case test case in EIP-55, 0x5aAeb6053F3E94C9b9A09f33669435E7Ef1BeAed. The hash of the lowercase version begins d385. The first letter, the a in position two, lines up with a 3 and stays small. The a in position three lines up with an 8 and turns into A. Of the eighteen letters in the address, nine end up capitalized. Now alter the ninth character from 3 to 4: the capitals stop agreeing with the new hash and a wallet that checks will refuse the address. EIP-55 gives the chance of a typo slipping through by luck as 0.0247%. The same address written in all lowercase is still accepted, but nothing checks it. We ran all four mixed-case test cases through our own Keccak-256 code before quoting any of them.

Never send funds to an example address. The ones printed in specifications are live: six of the eight in EIP-55 held ETH when we looked on October 12, 2026, including the one used above. A chain-by-chain list of examples that are safe to print is in crypto wallet address examples.

Flexdger Wallet draws no 0x address of its own. The receive sheet carries a short decorative label and a pattern that is not a QR code, so nothing on that screen can take a payment, and that is intended.

## Eighteen decimals, and the names for them

Ether is divisible down to 18 decimal places. The smallest piece, a wei, equals 10-18 ETH. A gwei is a billion wei, which makes 10-9 or 0.000000001 ETH. The Ethereum documentation reserves wei for technical work and gwei for fees a person reads. A home screen shows neither: it cuts ETH down to a few decimals.

How many is up to the wallet. Ours prints five decimals under 1,000 units and two above that. Around $2,530 per ETH, the fifth decimal (0.00001 ETH) is worth roughly 2.5 cents, so the quantity and the dollar value stay within a few cents of each other. Eight decimals on a list row would give precision nobody reads, while two could hide as much as $12.66 of rounding.

## Pick a quantity the way a buyer would end up with it

Our reference price is $2,532.78 per ETH, read on October 12, 2026 at about 12:35 UTC. Treat it as scale for the examples, not as a quote. Holdings built from dollar purchases rarely land on whole coins: $1,000 of ETH is 0.39482 ETH, and a bigger position could read 3.84128 ETH. A tidy 10 or 2.5 would read as typed, but real balances are what remains after buying in dollars at prices with decimals and paying fees.

Keep to the decimals the list displays. The dollar figure is calculated from what you typed, so a hidden sixth decimal makes the row disagree with a calculator. The whole-balance version of this check, across five tokens, is in [the crypto balance simulator](https://flexdger.com/blog/crypto-balance-simulator).

## A row you can rebuild with a calculator

Dollar value on the ETH row is quantity times live price: 3.84128 × $2,532.78 = $9,729.12. In our simulator, ETH is one of five built-in tokens whose price and 24-hour change refresh every 4 seconds, and the quantity is the one number you type. Every dollar of ETH movement shifts this row by $3.84, so on a recording the cents keep ticking every few seconds, as they do in an app.

The day-change figure takes a little more care. ETH was up 1.0892% when we read it, and the row shows +1.09%. That percentage applies to yesterday’s value: 9,729.12 divided by 1.010892 gives $9,624.29, so the move is **+$104.83**. Applying 1.0892% to today’s value would yield $105.97, which is $1.14 too much.

Now add 2,416.52 USDC. At $1.0008 that row is $2,418.45, down 0.01% (-$0.24). The header total reads $12,147.57 and its change is the sum of both rows, +$104.59. Its percentage is 104.59 over 12,042.98, which is **+0.87%**. A header that copied the ETH row’s +1.09% would be wrong. The same derivation, with fewer decimals, is on the [Bitcoin wallet simulator](https://flexdger.com/blog/bitcoin-wallet-simulator) page.

## Who else sits on an ETH screen

A wallet holding ETH usually holds ERC-20 tokens too, the standard proposed as EIP-20 in November 2015. Decimals are set per token, and wallets read them from the contract. We read these from Ethereum mainnet on October 12, 2026:

- **ETH**, 18 decimals: the native currency, the one that pays gas. Built in with a live price.
- **USDC**, 6 decimals: a dollar stablecoin issued by Circle. Built in with a live price.
- **USDT**, 6 decimals: a dollar stablecoin issued by Tether. A custom row with a price you type.
- **WETH**, 18 decimals: ETH wrapped as an ERC-20 token, redeemable one for one. A custom row with a price you type.

WETH is where mockups slip. By construction it equals exactly one ETH, yet a custom row holds the price you typed and never moves, so on video it separates from the live ETH row above it within seconds. Skip it, or make it a small row beneath the live ones. SOL, BTC and HYPE come built in as well; on an ETH-first screen, delete them from the token list or shrink them. The mirror-image choices on a SOL-first screen are in the [Solana wallet simulator](https://flexdger.com/blog/solana-wallet-simulator).

## The fee line that only a real send screen shows

Ahead of every send, a real wallet shows a network fee. The documentation’s formula is gas used times (base fee plus priority fee). The protocol sets the base fee and burns it; the priority fee, the tip, goes to the validator. A plain ETH transfer consumes 21,000 gas.

What that costs is a matter of the day. On October 12, 2026 we read 1,024 consecutive blocks from a public Ethereum node. The base fee ranged from 0.055 to 0.185 gwei, with a median of 0.090, and the median tip was 0.05 gwei. At 0.14 gwei a transfer comes to 21,000 × 0.14 = 2,940 gwei, or 0.00000294 ETH, which is **under one cent** at $2,532.78. Token transfers burn more: twenty-five USDC transfers measured across four blocks that day used between 40,360 and 62,272 gas, median 57,472, or about two cents.

The documentation’s own example assumes a 10 gwei base fee and a 2 gwei tip, which makes 252,000 gwei for the same transfer: about 86 times what we measured. Each is correct for its moment, and that is the lesson: a send screen has to quote a fee that matches the date printed on it. Our simulator sends nothing, so it shows no fee.

## What an ETH screenshot can never settle

Searches such as “fake eth wallet address” come from two kinds of people. Some want an address for a mockup. A mockup has no need for one that looks genuine, and an example copied from a web page may belong to someone with funds. The others were sent a screenshot with an address on it, and for them the rule is short: anyone can type a quantity beside any address, and an image holds nothing an explorer can verify.

A claim about holdings is settled by the address itself on an explorer, then by a message of your choosing, signed from that address. The [tells of a composed wallet screenshot](https://flexdger.com/blog/spot-a-fake-crypto-wallet-screenshot) help you doubt a picture, though they never replace that check. Our terms forbid presenting a simulator screen as proof of funds, and everything Flexdger Wallet draws is a mockup. For what it is meant for, a lesson, a deck, an explainer video, an ETH screen only needs to read right. [The live wallet is on the homepage](https://flexdger.com/).

Looking for a MetaMask larp specifically? [MetaMask larp wallet](https://flexdger.com/blog/metamask-larp-wallet) says what people mean by it and how to stage it safely.

## Sources

- Specifications: [ERC-55, mixed-case checksum address encoding](https://eips.ethereum.org/EIPS/eip-55) (2016).
- Documentation at ethereum.org: [Gas and fees](https://ethereum.org/developers/docs/gas/) (2026), [Intro to Ether](https://ethereum.org/developers/docs/intro-to-ether/) (2025), [ERC-20 Token Standard](https://ethereum.org/developers/docs/standards/tokens/erc-20/) (2026), [What is wrapped ether (WETH)](https://ethereum.org/wrapped-eth/) (2026).
- [Circle, USDC contract addresses](https://developers.circle.com/stablecoins/usdc-contract-addresses) (2026).
- Our own readings, October 12, 2026, from a public Ethereum node (ethereum-rpc.publicnode.com): fee history for blocks 26,175,411 to 26,176,434; gas used by transfers in blocks 26,176,435 to 26,176,438; decimals of the USDC, USDT and WETH contracts.
- [Binance public market data, ETHUSDT 24-hour ticker](https://api.binance.com/api/v3/ticker/24hr?symbols=%5B%22ETHUSDT%22%5D), read October 12, 2026.

## Questions

### How many decimals does ETH have?

Eighteen of them. The wei, smallest of all, is 0.000000000000000001 ETH, and the gwei, a billion wei, is 0.000000001 ETH. No wallet prints all eighteen on a home screen: a list row generally stops between four and six, and ours shows five below 1,000 ETH.

### What is gwei?

One of ether’s denominations: 1 gwei equals 0.000000001 ETH, which is a billion wei. Gas prices are quoted in it precisely because they are minute in ETH. With ETH at $2,532.78, a single gwei came to roughly $0.0000025.

### Why does an Ethereum address have capital letters?

Those capitals are a checksum, defined by EIP-55. Keccak-256 hashes the lowercase address, and a letter is capitalised wherever the matching digit of that hash reaches 8 or more. A wallet that verifies it will reject most typos; an address written entirely in lowercase stays valid but carries no check at all.

### How much gas does it cost to send ETH?

A plain ETH transfer burns 21,000 units of gas, and the fee is that gas times the base fee plus the priority fee, counted in gwei. On October 12, 2026 the base fees we read on Ethereum ran between 0.055 and 0.185 gwei, which put a transfer under a cent. Demand moves fees, so the figure belongs to its day and no other.

### Can an Ethereum wallet screenshot prove a balance?

No. Anybody can type a quantity beside any address, and a picture carries nothing an explorer could verify. What shows a balance is the address itself on an explorer, tied to whoever holds it by a message signed from that address. Our terms forbid putting a simulator screen forward as proof of funds.