A free online form to calculate billable time based on hh:mm:ss hours, minutes and seconds worked and providing billable time in decimals and then as the total billable.
This form is created in JotForm a stellar online forms creator that enables you to create a multitude of form types to share and embed on your website.
Other Apps that can help you with Time Tracking & Calculations
Clickup App - best for Time Tracking (and To-Do Lists, Project Management, Docs & Wikis, Spreadsheets, Email & Chat, Events, Reminders, Goal Tracking, Screenshots & Recording, Resource Management). Use Code 'SLICMEDIA' for 30% off the Unlimited Plan and 15% off the Business Plan and valid for 1 year.
Typeform - best for human form calculations, forms (with conditional logic), surveys and even E-Commerce.
Calconic - great for building advanced calculators for your website