# Implantation Calculator

URL: https://speedycalculator.com/calculators/health/implantation/
Last updated: 2026-10-30

> The implantation calculator estimates when a fertilised egg is likely to implant in the uterus – usually 6 to 12 days after ovulation – from your last period and cycle length or your ovulation date, and when a pregnancy test could turn positive.

## Inputs

- I know my…
- First day of your last period
- Average cycle length (days)
- Ovulation date

## Results

- Ovulation
- Earliest implantation
- Most likely implantation
- Latest implantation
- Earliest positive pregnancy test

## Formula

```
Ovulation ≈ LMP + cycle length − 14
Implantation = ovulation + 6 to 12 days (most often 8–10)
hCG detectable ≈ 2–3 days after implantation
```

## Explanation

After fertilisation the embryo travels down the fallopian tube for several days before burrowing into the uterine lining. Some people notice light spotting (implantation bleeding) at this time. A large study found most implantation happened 8–10 days after ovulation.

### How to use the Implantation Calculator

- **I know my…**
- **First day of your last period**
- **Average cycle length**
- **Ovulation date**

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Enter your last period and cycle length, or your ovulation date if you tracked it.

### Inputs explained

FieldWhat to enterI know my…Choose one: Last period and cycle length, Ovulation dateFirst day of your last periodA dateAverage cycle lengthIn daysOvulation dateA date

### What each result means

- **Earliest implantation** = [Ovulation] + 6
- **Most likely implantation** = [Ovulation] + 9
- **Latest implantation** = [Ovulation] + 12
- **Earliest positive pregnancy test** = [Ovulation] + 10

*Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.*

## Worked example

Inputs — I know my…: Last period and cycle length; First day of your last period: 2026-10-05; Average cycle length: 28 days.

Results — Ovulation = Mon, October 19, 2026; Earliest implantation = Sun, October 25, 2026; **Most likely implantation = Wed, October 28, 2026**; Latest implantation = Sat, October 31, 2026; Earliest positive pregnancy test = Thu, October 29, 2026.

## Key terms

- **Implantation**: Attachment of the embryo to the uterine lining.

## FAQ

**What does implantation bleeding look like?**
Light pink or brown spotting lasting a day or two, lighter than a period.

**Can I feel implantation?**
Some people notice mild cramps, but most feel nothing.

**When will a test be positive?**
Usually 2–3 days after implantation, often around the day of the missed period.


## Sources

- [Wilcox AJ et al. Time of implantation of the conceptus and loss of pregnancy. N Engl J Med, 1999](https://pubmed.ncbi.nlm.nih.gov/10362823/)