Days between dates
Knowing the exact number of days between two dates comes up more often than you'd expect. Project managers use it to measure how long a phase really took against the plan; freelancers and agencies use it for contract periods, notice periods and billing cycles; new parents track a baby's age in days through the first months. Enter any two dates above and you'll instantly see the full span broken down into total days, whole weeks plus leftover days, approximate months, and hours. The calculator handles varying month lengths, leap years and century rules automatically, so ranges crossing February 2024 come out exactly right. Swap the two dates and the sign flips — useful when direction matters, not just distance.
Working days vs calendar days
Businesses rarely think in calendar days. Invoicing terms, SLAs, shipping promises and payroll schedules all run on working days — Monday to Friday — which is why something promised in "5 business days" ordered on a Wednesday usually arrives the following Wednesday rather than Monday. The Working days card above counts weekdays only and skips weekends completely. What it deliberately does not do is subtract public holidays, because those depend on your country and often your state or province too. If one or two holidays fall inside your range, just subtract them from the working-days count yourself. As a rule of thumb, a year holds about 260 working days rather than 365 — roughly 71% of the calendar once weekends are removed.
Adding days to a date
The second mode answers a different question: pick a starting date, enter how many days to move — positive to go forward, negative to go back — and it returns the resulting date with the day of the week spelled out. Typical uses include estimating a delivery window ("ordered today, plus 12 days"), checking how much time remains on a 30-day return window, or finding when a free trial expires if you signed up on a known date. The weekday matters more than people realize: a trial expiring on a Saturday effectively gives you until Monday morning to cancel. The result updates live as you type or change the operation.