What are the recommended user gas prices?
Many people use the default gas price from their wallet when they make a transaction, and this is generally OK. However, sometimes it makes sense to pay more if you want the transaction mined quickly or you may want to save some money and offer a cheap gas price, especially if you don't care how quickly it is mined. In these cases, its hard to know what gas price to use unless you are monitoring the network (or checking this site frequently).
Therefore, we publish these recommendations (ETHgasAPI) to simplify the gas price choice based on desired transaction speed and cost:
1) Cheapest - This is the lowest gas price accepted by a top miner within the previous two days. This is a price that should result in the transaction being mined but may require ~ 5-15min before confirmation. This price is not guaranteed to result in acceptance so users who offer this gas price may sometimes need to resend the transaction at a later point.
2) Safe low - This is a gas price that is intended to be both cheap and successful. It may take a bit longer to get a confirmation with this price (e.g. 5minutes), but it is safer than using the cheapest price if you dont want to have to worry about the transaction being confirmed. This price is determined by having at least at least 50 transactions mined at this price within the prior two days AND at least 5% of the hash power accepting transactions with this price.
3) Average - This is the price accepted by top miners who account for at leat 50% of the blocks mined- safe and prompt. Usually reflects the wallet defaults.
4) Fastest - This is the lowest gas price that is accepted by all top miners (estimated over the last two days). Therefore, transactions with this gas price should be accepted by all the top pools. Paying more than this price is unlikely to increase transaction confirmation time under normal circumstances.