Log in to your uCalc account and go to the page with the list of your projects. Open the menu and click on the Get code button. The window with the embed HTML code will appear:
Proceed to managing your Tilda website. Choose a page and a desired place on it. Click on the + icon to add a new block:
Choose Other > HTML code:
Click on the Content button next to the new block:
Add the calculator embed code you've copied before (1) and close the block editor (2):
Publish the website. Done! Your calculator is all set.