You would like to buy your first NFT on opeansea.io? But you do not have ETH on the polygon network in your MetaMask wallet? You have no MATIC, the native coin of polygon in the wallet to pay for the first SWAP transaction? How can you quick and cheap transfer some fund from your binance account to your MetaMask wallet on the polygon network?
I had the same situation, I have spent hours to get some MATIC in my MetaMask wallet just to sign and pay the necessary fee to swap my BNB to ETH, so I could buy my very first NFT on opensea.io. I was totally frustrated because it was not as easy as it was presented in some older youtube videos.
Since the beginning of October 2021 polygon just increased the minimum gas fee to 0.001 MATIC per transaction, the available polygon faucet sites, like https://matic.supply just drops 0.0005 MATIC to your account, which is not enough to start to convert some BNB to ETH on the polygon network, thus min. 0.01 MATIC is the transaction fee of this SWAP.
TL;DR: If you are familiar with exchanges, SWAPs and bridges, you are going to need to do following steps to have ETH on your polygon wallet address in MetaMask:
Binance for fiat – crypto conversion. 10 USDC/(USDT) or DAI and 10 USD equivalent of BNB
xpollinate as bridge to send your USDC/(USDT) or DAI from BSC (Binance Smart Chain – BEP20) to your polygon address
polygon web wallet to swap USDC/(USDT) or DAI gas free to MATIC – 1 Matic
orbit bridge as bridge to send cheap BNB funds from BSC (BEP20) to polygon blockchain
quickswap to swap using your new MATIC to swap PBNB to ETH
Links to these sites:
https://wallet.polygon.technology/login/
https://quickswap.exchange/#/swap
Binance for fiat – crypto conversion
We need minimum 10 USDC (USDT) or DAI to withdraw from Binance using the BSC chain. The fee here will be 1 USDC/USDT. Also we need minimum 0.01 BNB (ca. 4.x USD). To buy the necessary minimum 10 USDC and 0.01 BNB, we have two options:
Use the Trade / Convert option, in this case minimum 20€ or $ must be converted per each coin/token, total 40 €/USD.
Use the Trade / Classic option, because here the minimum amount will be 10€/USD per coin/token, total 20 €/USD.
We need minimum 0.01 BNB for later, to withdraw from Binance to our MetaMask wallet, first to have some BNB to pay the transaction fees to transfer from BSC to polygon (bridge fee), and also later to buy some ETH.
To minimize cost, we need minimum 20 € or $ to be on our binance wallet. Because of creditcard (CC) topup fees, I suggest to choose min. 22 €/$ as topup amount.
If you want to use the Trade / Convert option, just double this, to min. 41 €/$. (Topup address for euro: https://www.binance.com/en/fiat/deposit/EUR, for USD: https://www.binance.com/en/fiat/deposit/USD.
If we topup our binance account with CC, the fee will be 1,8%, so from the 22 €/$, we are going to have 21,064 €/$. This will be enough, to buy under Trade / Classic 10 USDC(USDT). If you are not familiar with the Classic trading UI of binance, and want to use the Convert portal of binance, go to https://www.binance.com/en/convert and convert min. 20 €/$ to USDC or USDT and another 20 €/$ to BNB.
Now we have minimum 10 USDC(USDT) to be sent to our MetaMask wallet on BSC. Go to Wallet / Fiat and SPOT, choose there “Withdraw” on the top. Paste and copy your MetaMask wallet address into the “Adress field” and choose BSC (BEP20) as the blockchain you want to use to make the transaction. Network fee will be calculated later. Make the withdrawal.
If we trade the BNB, than we are going to have ca. 0.02x BNB on our Binance wallet. This will be transferred to our MetaMask wallet address, the same way using the above withdrawal process, but we choose BNB instead of USDC or USDT.
Now we have some USDC/USDT on our MetaMask wallet on the BSC blockchain, also some BNB. We have to get some MATIC, onto our polygon wallet. Let´s make the transfer from BSC to polygon using a bridge, like xpollinate.
xpollinate as bridge from BSC to polygon
To do the USDC/USDT transfer between the two blockchains, we need to add the polygon network to the MetaMask wallet, and also add the tokens MATIC, USDC or USDT and PBNB (for later BNB bridging). To do that, use following description: https://medium.com/stakingbits/setting-up-metamask-for-polygon-matic-network-838058f6d844
Token data to be added in MetaMask for USDT:
https://polygonscan.com/token/0xc2132d05d31c914a87c6611c10748aeb04b58e8f
USDT Contract address: 0xc2132d05d31c914a87c6611c10748aeb04b58e8f
Token data to be added in MetaMask for USDC:
https://polygonscan.com/token/0x2791bca1f2de4661ed88a30c99a7a9449aa84174
USDC contract address: 0x2791bca1f2de4661ed88a30c99a7a9449aa84174
Token data to be added in MetaMask for PBNB (Orbit Bridge Polygon Binance Coin):
https://polygonscan.com/token/0x7e9928afe96fefb820b85b4ce6597b8f660fe4f4
Contract address: 0x7e9928afe96fefb820b85b4ce6597b8f660fe4f4
Go to https://www.xpollinate.io and connect your MetaMask wallet to the website.
Following steps are necessary:
Choose on the top of the wite the Blockchain BSC
Choose the From blockchain BSC
Choose the token USDC or USDT you have on your wallet
Choos the To blockchain Polygon
Choose the Token you would like to get, in this case USDC or USDT
Choose the amount of Token you want to send from one to the other blockchain, I suggest to use minimum 1,1 USDC or USDT.
Click on SWAP.
You have to sign the contract in MetaMask, the transaction fee will be ca. 0.0013 BNB (at the writing of this article ca. 0,6 USD).
Now we have some USDC/USDT in our MetaMask wallet on the polygon network, but because we do not have enough MATIC to pay the gas fee, we must SWAP it. But how to do it, if we can not just withdraw MATIC from an exchange easily and cheap. We use the official polygon web wallet for that.
Get 1 MATIC on polygon web wallet to pay the gas fees
It will be more than enough 1 MATIC for a few transactions to be done on the polygon network, as of today (15.10.2021) ca. 0.001 MATIC, so more than 1000 transactions can be done, if we SWAP 1 MATIC.
Go to the official polygon wallet: https://wallet.polygon.technology/
Sign in with your MetaMask, just choose Polygon as blockchain in the app.
Choose MATIC and SWAP for Gas
Click on 1 MATIC
SWAP from, Select Token you transferred earlier (USDT or USDC, maybe DAI).
Click on Approve. Than on SWAP and in MetaMask you have to sign the contract.
After a few minutes, you have enough MATIC to pay gas fees for a few hundred transactions.
Orbit bridge as starting point for cheap BNB to ETH conversion
The cheapest way to get some ETH on the polygon network to your address is folowing:
Convert Fiat on binanc to BNB
Transfer BNB to the MetaMask wallet address
Use orbitbridge to move BNB from BSC to polygon as PBNB
SWAP PBNB to ETH
There are some good youtube videos about how to use orbitbridge, or you can use the How-to guide from OrbitBridge (https://bridge.orbitchain.io/assets/orbitbridge_guide_en.pdf) so I describe the process just briefly:
Click on “Select Coin”
Choose “BNB” than click on BSC in the “Select a Validator Group” and OK.
Under “From Chain” click on “Select Chain” and choose BSC from the dropdown list. If you are on the Polygon network in the MetaMask app, just switch to the BSC network.
Write in the input field the BNB you want to transfer. Leave enough BNB in the wallet, to pay the necessary fee, which will be ca. 0.0055 BNB
Under “To Chain” click on “Select Chain” and choose Polygon from the dropdown list.
Once you filled the BNB amount earlier, the PBNB amount will be filled out automatically.
Paste your wallet address from the MetaMask app into the field in the bottom and click on “Convert Now”.
You have to confirm the transaction on the website, and also in Metamask.
A few minutes later there will be the PBNB on your wallet in the polygon network
Now only one more step, to get to the ETH on the polygon network.
quickswap to SWAP PBNB to ETH
This is the really last step to get to the ETH, with we can pay the NFT on opensea.io.
Chose in MetaMask the Polygon network
In the from field you can choose PBNB. Set the amount of PBNB you would like to SWAP into ETH
Choose in the To field the ETH as target token
Click on the blue field “Swap”
Confirm SWAP again, sign in Metamask.
The Transaction fee will be ca. 0.01x MATIC.
Now you have ETH in your wallet, which can be spent for NFTs.
Some suggestions:
Give always some time for the network, sometimes it just needs a few minutes, to fulfil your transaction.
Try to avoid to transfer small amounts of BNB to ETH, because all bridges have their fees.
It is possible just to transfer USDT to the polygon network and SWAP USDT to ETH, but the fees will be way higher, than using the BNB to PBNB way, but you have to use one site less