The estimated calculator from TurboTax was recently updated. Use our calculator any maybe run a comparison using another online version via a Google search for 2018 estimated tax payment calculator.
Click the link below to get started.
https://turbotax.intuit.com/tax-tools/calculators/taxcaster/
You may also calculate your estimated taxes from within the TurboTax software as well as prepare 1040-ES payment vouchers by following these TurboTax FAQ steps:
Rest assured that TurboTax 2017 uses the 2018 tax rates recently passed by Congress and signed into law when calculating your 2018 estimated taxes."
[Edited 3.19.18 | 1:20 PM]