Conception Calculator
Highlight peak fertile days across cycles and show the estimated due date if conception happens that month.
Conception window
Counted from day 1 to the next day 1
Peak conception days
Wider fertile span Wed, Jun 24, 2026 – Tue, Jun 30, 2026
If conception happens this cycle, due around Mon, Mar 22, 2027
Sperm can remain viable for several days, so the window opens before ovulation. Within that span, the last few days usually carry the strongest odds.
Next six cycles
| # | Period | Ovulation | Peak days | Due if conceived |
|---|---|---|---|---|
| 1 | Mon, Jun 15, 2026 – Fri, Jun 19, 2026 | Mon, Jun 29, 2026 | Sat, Jun 27, 2026 – Mon, Jun 29, 2026 | Mon, Mar 22, 2027 |
| 2 | Mon, Jul 13, 2026 – Fri, Jul 17, 2026 | Mon, Jul 27, 2026 | Sat, Jul 25, 2026 – Mon, Jul 27, 2026 | Mon, Apr 19, 2027 |
| 3 | Mon, Aug 10, 2026 – Fri, Aug 14, 2026 | Mon, Aug 24, 2026 | Sat, Aug 22, 2026 – Mon, Aug 24, 2026 | Mon, May 17, 2027 |
| 4 | Mon, Sep 7, 2026 – Fri, Sep 11, 2026 | Mon, Sep 21, 2026 | Sat, Sep 19, 2026 – Mon, Sep 21, 2026 | Mon, Jun 14, 2027 |
| 5 | Mon, Oct 5, 2026 – Fri, Oct 9, 2026 | Mon, Oct 19, 2026 | Sat, Oct 17, 2026 – Mon, Oct 19, 2026 | Mon, Jul 12, 2027 |
| 6 | Mon, Nov 2, 2026 – Fri, Nov 6, 2026 | Mon, Nov 16, 2026 | Sat, Nov 14, 2026 – Mon, Nov 16, 2026 | Mon, Aug 9, 2027 |
Estimate only — not medical adviceView details
These dates are calendar estimates from average cycle and pregnancy lengths. They are not a diagnosis, not contraception, and not a substitute for clinical care. Talk with a qualified clinician about your situation.
How it works
The conception calculator highlights higher-probability fertile days across upcoming cycles and can show an estimated due date if conception occurred in a given cycle window.
It builds on period start and cycle-length assumptions similar to ovulation tools, then emphasizes the days most often associated with conception chances in average cycles.
Peak days are still probabilistic. Timing helps, but it does not guarantee pregnancy, and fertile windows can miss the mark when ovulation shifts.
If you conceive, due-date math from conception differs slightly from LMP dating. Your clinician will confirm dating with history and ultrasound as needed.
For detailed ovulation ranges, use the Ovulation Calculator. For pregnancy timelines after you have a reference date, use Due Date or Pregnancy tools.
Frequently asked questions
- Does sex on the peak day guarantee pregnancy?
- No. Even with well-timed intercourse, conception is uncertain in any given cycle. Timing improves chances; it does not control every biological factor.
- How is this different from the ovulation calculator?
- Both use cycle averages. Conception framing emphasizes fertile-day highlighting and due-date implications; ovulation framing emphasizes ovulation timing and fertile windows.
- We have been trying for months—what next?
- Guidelines for when to seek fertility evaluation depend on age and history. A calculator cannot triage that—talk with a clinician.
- Can tracking apps disagree with this tool?
- Yes. Different apps use different defaults and learning algorithms. Consistency within one method matters more than matching every app.
Related calculators
- Due Date CalculatorEstimate a pregnancy due date from last period, ultrasound dating, conception date, or IVF embryo transfer.
- Pregnancy CalculatorTrack gestational age, trimester, and milestone dates from LMP, due date, ultrasound, conception, or IVF.
- Ovulation CalculatorProject ovulation days and fertile windows for upcoming cycles from your last period and cycle length.
- Period CalculatorForecast upcoming period and ovulation dates using your last period start, cycle length, and bleeding days.