Date Calculator
Find the days between two dates, or add and subtract days, weeks, months and years.
Your input is processed in your browser.
Dates
Choose a start and end date to see the difference.
Private by design
Your data is processed directly in your browser. It is not sent to Stay Local Tools servers for processing. Because the work happens on your device, nothing you type here leaves your browser unless you choose to copy or share it yourself.
Note: the website itself still loads normal web files, and may use analytics or ads later. The promise here is about the files and text you put into these tools.
How to Use
- Date Difference: choose a start date and an end date to see the days between them.
- Add / Subtract: choose a base date, then Add or Subtract a number of days, weeks, months or years.
- Use Today to jump to the current date, or Swap to flip the start and end dates.
Date difference
Date difference counts how many days sit between two calendar dates. This tool shows the exact total, plus the same amount expressed as weeks and days, and as a calendar difference of years, months and days — the way you would normally describe someone's age or how long ago something happened.
Days vs calendar months
A day is always the same length, so a total day count is always exact. A month is not — it can be 28, 29, 30 or 31 days long, so "1 month" means a different number of days depending on which month it is. The calendar difference shown here (years, months, days) reflects that, rather than pretending every month is a fixed length.
Why month lengths differ, and leap years
February normally has 28 days, but every 4 years (except most century years) it has 29 — a leap year, which keeps the calendar lined up with the Earth's orbit. This tool checks for leap years automatically wherever February is involved.
Adding and subtracting calendar dates
Adding days or weeks is simple counting. Adding months or years is calendar-aware: if the result would land on a day that does not exist in the target month — like January 31 plus one month — the date is moved back to the last real day of that month (February 28 or 29) instead of quietly spilling over into March.
Questions and Answers
By default, no — it counts the number of full days between the two dates. Turn on "Include end date" if you want the count to include both the start and end day, such as when counting the total days of a trip.
The calendar difference (years, months, days) is calculated the same way a person's age is usually stated — by comparing calendar months and days, not by assuming every month is 30 days. The Total Days figure is always an exact day count.
Yes. February has 29 days in a leap year, and all calculations here account for that automatically.
No. All date calculations run directly in your browser using standard JavaScript date logic. Nothing is sent to Stay Local Tools servers.
It becomes February 28 (or February 29 in a leap year) — the last valid day of February, since January 31 has no exact equivalent in a shorter month. This tool never rolls extra days over into the next month.
Other Languages
Español
Calculadora de fechas
Calcula los días entre dos fechas, o suma y resta días, semanas, meses y años a una fecha. El dato se procesa directamente en tu navegador y no se sube a los servidores de Stay Local Tools para el procesamiento.
Preguntas frecuentes
Por defecto no; cuenta los días completos entre las dos fechas. Activa "Incluir fecha final" si quieres contar también el día de inicio y el final.
La diferencia de calendario (años, meses, días) se calcula comparando meses y días del calendario, no asumiendo que cada mes tiene 30 días.
Sí. Febrero tiene 29 días en un año bisiesto, y todos los cálculos lo consideran automáticamente.
Português (Brasil)
Calculadora de datas
Calcule os dias entre duas datas, ou some e subtraia dias, semanas, meses e anos de uma data. O dado é processado diretamente no navegador e não é enviado aos servidores do Stay Local Tools para processamento.
Perguntas frequentes
Por padrão não; ela conta os dias completos entre as duas datas. Ative "Incluir data final" se quiser contar também o dia de início e o final.
A diferença de calendário (anos, meses, dias) é calculada comparando meses e dias do calendário, sem supor que todo mês tem 30 dias.
Sim. Fevereiro tem 29 dias em um ano bissexto, e todos os cálculos aqui consideram isso automaticamente.
한국어
날짜 계산기
두 날짜 사이의 일수를 계산하거나 날짜에 일, 주, 개월, 연 단위 기간을 더하고 뺄 수 있습니다. 데이터는 브라우저에서 직접 처리되며 Stay Local Tools 서버에 업로드되지 않습니다.
자주 묻는 질문
기본적으로는 포함되지 않으며 두 날짜 사이의 전체 일수만 계산합니다. 시작일과 종료일을 모두 포함하고 싶다면 "종료일 포함"을 켜세요.
달력 차이(연, 월, 일)는 한 달을 30일로 가정하지 않고 실제 달력의 월과 일을 비교해 계산합니다.
네. 윤년에는 2월이 29일이며 모든 계산에서 이를 자동으로 반영합니다.