How can I use Shipping Rates Calculator+ for delivery estimates in holidays?

The main goal of the app is to show the shipping rates on the cart page.

Shipping Rates Calculator+ displays your shipping rates exactly as they are configured in your Shopify admin.

However, as Shopify provides delivery estimates when a real-time carrier is used, we also give the option to show those estimates.

What we do is display the estimates as Shopify gives them to us and Shopify claims to give them to us as the carriers provide them. Regarding holidays, as far as we know, FedEx takes them into account, but some other carriers don't.

In order to mitigate the issue, there are a few things that you can do with our app.

1. Add some cutoff days to be on the safe side; you can do that on the  Real-time carriers section on the app preferences page:

2. Change the ' Get it by' text to something like 'Approx. delivery by'. This can be found in the Visual preferences section:

You can also change the date format of your Estimated Delivery by clicking the Delivery date button at the bottom of the Delivery Estimate Prefix option:

3. Explain that the delivery estimates are indeed estimations in the Shipping note:

The app cannot be used to configure shipping rates, only to display them. 

Please note that with the steps mentioned above you can edit the configuration of the app to provide more accurate information to your clients when the holiday's time arrives and some delays can be expected.