I see many warnings against the use of now (block.timestamp) in solidity code but no one mentions any alternative of getting the time. What is the alternative of using now?

1 Answer 1


The main issue with using block.timestamp is that it is manipulable by miners and random fluctuations to within an hour or so. For minute-scale time, you should use block.number * 15, which also can fluctuate but is less arbitrarily manipulable.

On the scale of days or more, block.timestamp will be far more accurate, since it is tied to real unix time.

  • can you explain why block.number * 15? are u assuming a block every 15 seconds?
    – Zaid Amir
    Commented Mar 19, 2018 at 14:56
  • Yes, on average. It's actually more like 14 now, but regardless it's actually random so you're not going to get great accuracy Commented Mar 19, 2018 at 18:09

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