You can use
bitaddress to derive the public key.
You only need to click on "Wallet Details" button and enter your private key.
Bitaddress is an excellent tool. BUT never use it from the web-page. You are supposed to download a copy of bitaddress to your own machine, and use it locally. Preferably offline and after verifying the download.
You really wouldn't want to put bitcoins to an address, which has a private key that has been in the internet
As said, Electrum is a good choice too. Just double check that you download it from the right web-page. As there are web-pages that look a lot like official Electrum pages, but give you a hacked version of it. And you will end up losing your coins if you use them.