In this track: Digital value and units
Convert Wei to ETH by hand
Divide a whole Wei amount by 10¹⁸ to display ether.
Pouring small measuring cups into a large jug changes the count you report, not how much liquid you have.
1 ETH = 1000000000 Gwei = 1000000000000000000 Wei.
Start with the exact integer
Take 42000000000000000 Wei. Keep all its digits. You do not need to convert it into an ordinary floating-point number to display it. The number represents a count of indivisible Wei.
Place eighteen decimal digits
Divide by 1,000,000,000,000,000,000. One practical method is to pad the integer to at least nineteen digits, then place a decimal point eighteen digits from the right. The example becomes 0.042000000000000000 ETH.
Trim display zeros carefully
Removing trailing zeros after a decimal point gives 0.042 ETH. That formatting change is exact. Removing a non-zero digit, such as the final digit of 0.000000000000000001 ETH, changes the represented amount and must not happen silently.
Try the smallest case
Convert one Wei. The answer is 0.000000000000000001 ETH, not zero. If an interface displays 0.00 ETH, it may be a rounded preview rather than the full balance. Use the exact converter to inspect the original units.
What is 42000000000000000 Wei in ETH?
Place the decimal eighteen digits from the right, then trim only trailing fractional zeros.
Original explanations by EtherTools. Examples are educational and source-linked; this site is independent of the Ethereum Foundation. Our approach.