About the Time Between Dates
Date and time calculators handle the arithmetic of calendars and durations, which is trickier than it looks — months have different lengths, years have leap days, and time zones add complexity to any cross-date calculation.
How date math works
- Adding days is straightforward. Adding months or years requires careful handling of month-end dates — "1 month after January 31" is February 28 (or 29 in a leap year), not February 31.
- Business day calculations exclude weekends and optionally holidays. These require a specific holiday calendar to be accurate.
- Age is usually measured in full years elapsed, though the exact moment of the birthday determines whether it's been reached.
Common uses
- Project deadlines and milestone planning
- Legal and contractual date calculations (90-day cure periods, notice windows)
- Financial calculations using day-count conventions (Actual/365, Actual/360, 30/360)
- Personal planning: countdown timers, anniversary tracking, elapsed time
Precision note
If your calculation has legal or contractual significance, verify the result — some jurisdictions count the first day, some count only the last, and banking uses different day-count conventions than calendar math.
Frequently Asked Questions
How accurate are the results?
The Time Between Dates applies a standard formula to your inputs — accuracy depends on how precisely you measure those inputs. For planning and estimation, results are reliable. For high-stakes or professional decisions, cross-check the output with a domain expert or primary source.
Can I use this on mobile?
Yes — the calculator is designed to work on any device. For complex multi-input calculations on small screens, landscape orientation gives more room to see all fields and results simultaneously.
Common Tip Percentages
| Service | Typical Tip Range | Notes |
|---|---|---|
| Restaurant (sit-down) | 15–20% | 20%+ for exceptional service |
| Food delivery | 10–20% | Consider extra for long distances |
| Taxi / rideshare | 10–20% | More for assistance with luggage |
| Hotel housekeeping | $2–5/night | Leave daily, not just at checkout |
| Barber / hair salon | 15–20% | On pre-discount total |
| Pizza delivery | 10–15% or $3–5 minimum | Higher in bad weather |
General Household Budget Ratios (50/30/20 Rule)
| Category | % of Net Income | Examples |
|---|---|---|
| Needs | 50% | Rent, groceries, utilities, insurance |
| Wants | 30% | Dining out, entertainment, hobbies |
| Savings / Debt | 20% | Emergency fund, retirement, extra payments |
Common Measurement Conversions for Everyday Use
| Quantity | US / Imperial | Metric Equivalent |
|---|---|---|
| 1 cup | 8 fl oz | 237 mL |
| 1 pint | 16 fl oz | 473 mL |
| 1 quart | 32 fl oz | 946 mL |
| 1 gallon | 128 fl oz | 3.785 L |
| 1 lb | 16 oz | 453.6 g |
| 1 ft | 12 in | 30.48 cm |