Months Calculator - Add, Subtract, or Compare Months

Interactive Months Calculator

Choose an operation, adjust the base date, and enter months or a second date. The calculator accounts for variable month lengths by converting offsets into actual calendar months and rounding the difference result to two decimals as requested for financial-grade reporting.

Operation:
+

Result

Target Date

March 26, 2026

Thursday

Relative Distance

90.0 days ahead

(90.0 days)

ISO Timestamp

2026-03-25T16:00:00.000Z

Paste this value into spreadsheets or contracts.

The target date lands 90.0 days ahead (3 months after the anchor). Mention 2026-03-25T16:00:00.000Z in documentation so everyone references the same timestamp.

Plan billing cycles, academic terms, and renovation phases with a months calculator that handles complex calendar math. Enter any base date, add or subtract months (including fractions), or compare two dates to see the exact number of months between them with two-decimal precision.

Each result includes the formatted date, ISO string, and an explanation written in plain English so you can paste answers into proposals, statements of work, or cross-functional status updates without rewriting the details.

Quick Reference: 1-24 Months Ahead and Behind

Scan the quick reference table to see what date falls N months from today. The second column lists the same offset in the past, giving you a fast way to double-check compliance windows, warranties, or subscription terms.

MonthsMonths From NowMonths AgoISO (Future)ISO (Past)
1Jan 26, 2026Nov 26, 20252026-01-262025-11-26
2Feb 26, 2026Oct 26, 20252026-02-262025-10-26
3Mar 26, 2026Sep 26, 20252026-03-262025-09-26
4Apr 26, 2026Aug 26, 20252026-04-262025-08-26
5May 26, 2026Jul 26, 20252026-05-262025-07-26
6Jun 26, 2026Jun 26, 20252026-06-262025-06-26
7Jul 26, 2026May 26, 20252026-07-262025-05-26
8Aug 26, 2026Apr 26, 20252026-08-262025-04-26
9Sep 26, 2026Mar 26, 20252026-09-262025-03-26
10Oct 26, 2026Feb 26, 20252026-10-262025-02-26
11Nov 26, 2026Jan 26, 20252026-11-262025-01-26
12Dec 26, 2026Dec 26, 20242026-12-262024-12-26
13Jan 26, 2027Nov 26, 20242027-01-262024-11-26
14Feb 26, 2027Oct 26, 20242027-02-262024-10-26
15Mar 26, 2027Sep 26, 20242027-03-262024-09-26
16Apr 26, 2027Aug 26, 20242027-04-262024-08-26
17May 26, 2027Jul 26, 20242027-05-262024-07-26
18Jun 26, 2027Jun 26, 20242027-06-262024-06-26
19Jul 26, 2027May 26, 20242027-07-262024-05-26
20Aug 26, 2027Apr 26, 20242027-08-262024-04-26
21Sep 26, 2027Mar 26, 20242027-09-262024-03-26
22Oct 26, 2027Feb 26, 20242027-10-262024-02-26
23Nov 26, 2027Jan 26, 20242027-11-262024-01-26
24Dec 26, 2027Dec 26, 20232027-12-262023-12-26

Months offset visualization

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Use the chart to spot quarter and semiannual markers at a glance.

Planning more than two years out? Extend the pattern by continuing to add months through the calculator’s add mode. The quick reference table gives you the first two years of context instantly, which is perfect for subscription services, B2B retainers, and academic program launches.

How Teams Rely on the Months Calculator

Month-level planning shows up everywhere from banking to household budgeting. These scenarios highlight how the months calculator keeps everyone aligned.

  • Retainers and service packages

    Agencies map the exact end date for 6- or 12-month retainers, then subtract months to set invoicing and wrap-up checkpoints.

  • Academic and licensing timelines

    Schools and certification bodies add months to determine semester breaks, continuing education deadlines, and test registration windows.

  • Home renovation or maintenance

    Homeowners break large projects into month-sized tasks and subtract months to plan material ordering and crew availability.

Best Practices for Monthly Forecasting

Keep your calculations defensible with the following monthly planning tips.

Document the averaging rule

Mention that fractional month math uses 30.4375 days per month. This transparency prevents confusion when finance teams compare your numbers against exact month calendars.

Lock a reference timezone

Every displayed date uses your browser’s timezone. Add a quick note when sharing cross-region timelines so colleagues know whether they should convert to UTC or keep the local zone.

Pair months with weeks

For projects that require weekly reporting, run your date through this months calculator and the week calculator to capture both datapoints in one meeting.

Frequently Asked Questions

Each answer tackles a common question teams raise when working with month-level offsets.

How does the months calculator handle different month lengths?

When you add or subtract months, the tool shifts the calendar month and keeps the same day when possible. For fractional months, it converts the fraction into days using the length of the target month. This approach mirrors how finance teams pro-rate contracts.

Why does the months-between result show two decimals?

Many stakeholders request a two-decimal months figure because it aligns with amortization schedules, SaaS billing, and installment loans. The calculator automatically applies that rounding so you can copy the answer directly into your documents.

Will leap years change the math?

Leap years and varying month lengths are accounted for because all calculations use JavaScript dates under the hood. February 29 is preserved when possible, and fractional conversions rely on each specific month’s length.

Last updated: November 24, 2025