Growth & Weight Guide

Boston Terrier Growth Chart — Weight by Age & Size Guide

Updated April 202610 min readVet-reviewed sources

How much should your Boston Terrier weigh at each age? When do they stop growing? This guide covers month-by-month weight ranges for both male and female Boston Terriers, growth milestones, when growth plates close (and why that matters for exercise), feeding guidelines by stage, and the warning signs that something might be off — all backed by veterinary research including population-level data from over 6 million dogs.

Adult Weight♂ 12-25 lbs (5-11 kg)
♀ 10-21 lbs (5-10 kg)

Adult Height♂ 12-18 in
♀ 10-15 in

Full GrownHeight: 8-10 months
Weight: 10-12 months

Size Categorysmall
12-15 years

Boston Terrier Weight Chart by Age

Weight ranges shown are for healthy Boston Terriers at ideal body condition. Your puppy should fall within these ranges — being slightly below the range is better than above for long-term joint health.

♂ Male Boston Terrier Weight

Age	Weight (lbs)	Weight (kg)	Notes
Birth	3.2-8.0 oz	0.1-0.2	Born blind and deaf
1 month	1-2	0.5-0.9
2 months	2-4	1.0-2.0	Typical adoption age
3 months	4-8	1.8-3.7
4 months	6-12	2.6-5.4	~50% of adult weight
5 months	7-15	3.3-6.8
6 months	9-18	3.9-8.2
7 months	10-20	4.4-9.3
8 months	11-22	4.8-10.0
9 months	11-23	5.1-10.5	Near final weight
10 months	12-24	5.3-11.0	Near final weight
12 months	12-25	5.4-11.3	Fully mature

♀ Female Boston Terrier Weight

Age	Weight (lbs)	Weight (kg)	Notes
Birth	3.2-6.4 oz	0.1-0.2	Born blind and deaf
1 month	1-2	0.4-0.8
2 months	2-4	0.9-1.7	Typical adoption age
3 months	3-7	1.5-3.2
4 months	5-10	2.2-4.6	~50% of adult weight
5 months	6-13	2.8-5.8
6 months	7-15	3.3-6.9
7 months	8-17	3.8-7.9
8 months	9-19	4.1-8.5
9 months	10-20	4.3-8.9	Near final weight
10 months	10-21	4.5-9.3	Near final weight
12 months	10-21	4.6-9.6	Fully mature

Boston Terrier Growth Milestones

10-14 days

Eyes open

Initially blurry vision, full sight by 8 weeks

14-21 days

Ears open

Ear canals sealed at birth

3-6 weeks

Baby teeth erupt

28 deciduous teeth total

6-8 weeks

Fully weaned

Should be eating puppy food exclusively

3-4 months

Permanent teeth start

Adult teeth replacing baby teeth

6-7 months

All 42 adult teeth

Retained baby teeth need vet extraction

9-12 months

Sexual maturity

Females: first estrus. Males: producing sperm

10-12 months

Growth plates close

Safe for higher-impact exercise after this point

10-12 months

Full physical maturity

Final weight reached, fully developed

Growth Concerns for Boston Terriers

Maintain healthy weight during growth

Keeping your Boston Terrier at a healthy weight during growth sets the foundation for lifelong joint health. The Purina LifeSpan Study proved lean dogs live 1.8 years longer.

Weigh monthly and compare to the growth chart. You should always be able to feel ribs with light pressure.

Exercise limits during growth

Growth plates are the weakest point in developing bones. High-impact exercise before they close can cause permanent damage. Growth plates close at approximately 10-12 months for Boston Terriers.

Moderate walks. Watch for back issues in long-bodied breeds.

Feeding Guide by Growth Stage

Stage	Meals/Day	Food Type	Amount
8-12 weeks	3x	Puppy formula	Follow label — divide daily amount into 3 meals
3-6 months	2x	Puppy formula	Peak growth — do NOT exceed label recommendation
6-12 months	2x	Puppy formula	Growth slowing — reduce if gaining too fast
10-12 months	2x	Transition to adult formula	Gradually mix over 7-10 days

See our full Boston Terrier Diet & Nutrition Guide for detailed caloric needs, macros, and breed-specific dietary risks.

Exercise Guide by Growth Stage

0-3 months

Supervised free play only

Short play sessions on soft surfaces. No structured walks until vaccinations complete.

3-6 months

5 min per month of age

A 4-month-old gets 20 minutes of structured walking. Free play in yard is fine.

6-12 months

Moderate walks, swimming

30-45 min walks. Swimming is excellent low-impact exercise. Gradually increase intensity.

10-12 months+

Full activity

Growth plates closed. Safe for running, hiking, agility, and all activities. Build endurance gradually.

When to Worry — Growth Red Flags

Not gaining weight for 2+ weeks

Could indicate parasites, illness, or inadequate nutrition. Vet check recommended — bring a stool sample.

Gaining too fast (above chart range)

Reduce food by 10%. Excess weight stresses developing joints. Reweigh in 2 weeks.

Limping or reluctance to play

Could indicate injury or joint issues. Vet exam recommended.

Distended belly despite thin body

Classic sign of intestinal parasites (roundworms, hookworms). Vet visit for deworming.

Baby teeth not falling out by 7 months

Retained deciduous teeth cause dental crowding. Vet extraction may be needed.

Frequently Asked Questions

Boston Terriers reach adult height by approximately 8-10 months when growth plates close, but continue filling out until 10-12 months. Males typically reach 12-25 lbs, females 10-21 lbs.

A rough predictor for small breeds: your puppy's weight at 14 weeks is approximately 50% of adult weight. Males typically reach 12-25 lbs; females reach 10-21 lbs.

Compare to the growth chart above, matching age and gender. More important than the number: you should feel ribs with light pressure (BCS 4-5/9). If you can't feel ribs, reduce food by 10%.

A puppy formula from a reputable brand. Feed 3 meals/day until 6 months, then 2 meals/day. Switch to adult food at 10-12 months.

Wait until growth plates close — approximately 10-12 months. Before this, follow the 5-minute-per-month-of-age rule for structured walks.

Early spay/neuter delays growth plate closure (Root Kustritz, 2007), resulting in slightly taller dogs with longer limbs. However, neutered dogs have higher obesity risk — monitor food intake.

Lean is actually ideal during growth. BCS 4/9 (ribs easily felt, visible waist) is the target. The Purina LifeSpan Study proved lean dogs live 1.8 years longer with less arthritis.

Sources

AKC Breed Standard — Boston Terrier — official height and weight ranges (2024)

Salt C et al. — Growth standard charts for monitoring bodyweight in dogs — PLOS ONE (6 million dogs) (2017)

Hawthorne AJ et al. — Body-weight changes during growth in puppies — Journal of Nutrition (2004)

Kealy RD et al. — Effects of diet restriction on life span in dogs — JAVMA (Purina LifeSpan Study) (2002)

Growing Boston Terriers face real health risks

Health conditions that develop during growth can be expensive to treat. Pet insurance covers hereditary and congenital conditions when diagnosed after enrollment.

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