5 weeks pregnant

What happens at 5 weeks pregnant?
At 5 weeks a baby is around 0.2 cm long, about the size of a grain of raw sugar. That is roughly 1 month, in the first trimester, with about 35 weeks to go until 40.
Published length
0.2 cm long
In months
Roughly 1 month
Trimester
first · 35 weeks to go
What is developing at 5 weeks
The neural tube, which becomes the brain and spinal cord, is closing along the length of the embryo. A tiny heart tube has begun to beat, far too faint for anyone to hear. This is the week most people get a positive test, because the pregnancy hormone hCG has finally built up enough to show.
The size comparison above is a grain of raw sugar, which measures 0.2 cm across. Every comparison on this site is a real object with a real measurement, checked against the published length. The same week is drawn in seven other sets below, from Australian animals to fast food, if this one means nothing to you.
5 weeks, in eight rulers
Every other pregnancy tool measures a baby in fruit. This one offers eight sets to choose from, and each object below carries its real measurement, checked against the 0.2 cm the NHS publishes for week 5. Pick whichever ruler you actually have a feel for. Why not fruit.

Sweet treats
a grain of raw sugar
0.2 cm across

Australian animals
a sand fly
0.2 cm end to end

The 90s
the tip of a Lite-Brite peg
0.2 cm across the point

Sport
a dimple on a golf ball
0.2 cm across one dimple

Things you already own
a grain of sand
0.2 cm across a coarse grain

Gaming
the pip on a d6
0.2 cm across

Fast food
a bubble in the soft drink
0.2 cm across

Toys
a grain of kinetic sand
0.2 cm across
Your dates, from 5 weeks
Set to someone who is exactly 5 weeks today, so the due date below is the one that implies. Change the date to your own and everything follows from it — nothing is saved unless you do.
How far along am I?
Do not know your due date yet? The due date calculator estimates one from your last period. A dating ultrasound is more accurate than any calendar method — if your pregnancy care team has given you a date, use theirs.
Questions about 5 weeks
- How many months is 5 weeks pregnant?
- 5 weeks is roughly 1 month. Months are an awkward unit in pregnancy because they do not divide evenly into weeks — a calendar month averages about 4.3 weeks, which is why 40 weeks works out a little over nine months rather than ten. Appointments and scans are always booked in weeks, so weeks are the figure worth carrying.
- How big is a baby at 5 weeks?
- The NHS publishes around 0.2 cm long for week 5. Rather than one fruit, that length is offered here against eight rulers, each object carrying its own measurement: a grain of raw sugar (0.2 cm across), a sand fly (0.2 cm end to end), the tip of a Lite-Brite peg (0.2 cm across the point), a dimple on a golf ball (0.2 cm across one dimple), and four more. Published lengths are averages across many babies, not a measurement of any particular one, and a scan estimate that differs is a normal thing rather than a finding.
- What trimester is 5 weeks?
- Week 5 is in the first trimester, on the commonly published split of weeks 1–12, 13–26 and 27 onward. The boundaries are conventions for talking about pregnancy rather than biological switches — nothing changes overnight at week 13 or week 27.
Where these numbers come from
- NHS — Week-by-week guide to pregnancy — The published length of a baby at each week of pregnancy — measured head to bottom until week 20 and head to heel from week 20 — and what is developing at that stage.
- Pregnancy, Birth and Baby — Pregnancy week by week — The Australian Government health service’s week-by-week account of how a pregnancy is counted and what develops at each stage.
Stop doing this maths in your head
Once the counting turns into feeds, sleeps and nappies, BubSync keeps that record shared across everyone caring for your baby.
