Before you print
How big should it be?
Rule of thumb: printed width ≥ scanning distance ÷ 10. Pick the surface above and the studio sizes the code for you, then checks the printed module size against what a press can actually hold.
Questions people actually ask
It opens the sender's wallet — MetaMask, Rainbow, Trust, and others — with your address filled in, plus the network and amount if you set them. It uses the EIP-681 ethereum: standard.
The same 0x address exists on Ethereum mainnet, Base, Arbitrum, and other chains, but funds sent on the wrong one can be hard to recover. Picking the network stamps the intended chain into the code.
Wei is Ethereum's smallest unit and avoids decimal rounding: 1 ETH is exactly 1000000000000000000 wei (18 zeros). Leave it empty and the sender types an amount in their wallet instead.
Never — the code is just a payment URI with your address in it, generated in your browser. Payments go wallet-to-wallet on-chain, and the generator is free forever with no signup.
Want the detail? How ethereum QR codes work — the payload format, what scanners do with it, and where it breaks.