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Date addition/subtraction calculates the resulting date after adding or removing days, automatically handling month boundaries, varying month lengths, and leap years.

公式

Result date = Start date + n days | Leap year every 4 years except centuries (divisible by 400)

n: Number of days (days)
d_start: Start date (YYYY-MM-DD)

ステップバイステップガイド

1Add days to get future date; subtract to get past date
2Leap years add February 29 every 4 years (with century exceptions)
3Business day calculators exclude weekends and public holidays
4ISO 8601 format (YYYY-MM-DD) avoids ambiguity

解いた例

入力

15 February + 14 days

結果

1 March (or 29 February in a leap year)

よくある質問

What is Add Days?

Date addition/subtraction calculates the resulting date after adding or removing days, automatically handling month boundaries, varying month lengths, and leap years. Use this calculator for accurate, instant results.

How accurate is the Add Days calculator?

The calculator uses the standard published formula for add days. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.

What units does the Add Days calculator use?

This calculator works with inches. You can enter values in the units shown — the calculator handles all conversions internally.

What formula does the Add Days calculator use?

The calculator applies the standard formula for this type of calculation. See the 'How It Works' steps above for the detailed formula breakdown.

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