Baby Size Everyday Objects worksheet

1. Closest object by weight: A half gallon of water

1. A due date is 280 days after the first day of the last period, so count back 280 days to find that starting day

   $\text{Mar 4, 2026}\text{−}280\text{\hspace{0.17em}days}$$=\text{May 28, 2025}$

2. Count the days from the first day of the last period to the counting-from date

   $\text{Jan 6, 2026}\text{−}\text{May 28, 2025}$$=223\text{\hspace{0.17em}days}$

3. Split the days into whole weeks and leftover days, since pregnancy is counted in weeks

   $223\text{÷ 7}$$=\text{31 weeks, 6 days}$

4. Put week 31 into the Hadlock formula for typical weight. The answer is the natural log (ln) of the weight in grams

   $0.578\text{+}0.332\text{×}31-0.00354\text{×}31\text{²}$$=7.4681$

5. Undo the log by raising e (about 2.718) to that power, then round to the nearest gram

   $e^{7.4681}$$=\mathrm{1,751}\text{\hspace{0.17em}g}$

6. Find the object nearest in weight, a half gallon of water. Divide the baby's typical weight by its weight to compare them

   $\frac{\mathrm{1,751}\text{\hspace{0.17em}g}}{\mathrm{1,891.48}\text{\hspace{0.17em}g}}$$=0.93$

7. The ratio is between 0.67 and 1.5, so the two weigh about the same. That makes it a fair match

   $0.93\text{is within 1.5 times either way →}\text{A half gallon of water}$

2. Closest object by weight: A quart of water

1. Put week 24 into the Hadlock formula for typical weight. The answer is the natural log (ln) of the weight in grams

   $0.578\text{+}0.332\text{×}24-0.00354\text{×}24\text{²}$$=6.507$

2. Undo the log by raising e (about 2.718) to that power, then round to the nearest gram

   $e^{6.507}$$=670\text{\hspace{0.17em}g}$

3. Find the object nearest in weight, a quart of water. Divide the baby's typical weight by its weight to compare them

   $\frac{670\text{\hspace{0.17em}g}}{945.74\text{\hspace{0.17em}g}}$$=0.71$

4. The ratio is between 0.67 and 1.5, so the two weigh about the same. That makes it a fair match

   $0.71\text{is within 1.5 times either way →}\text{A quart of water}$

3. Closest object by weight: A dollar's worth of nickels (20 coins)

1. Put week 16 into the Hadlock formula for typical weight. The answer is the natural log (ln) of the weight in grams

   $0.578\text{+}0.332\text{×}16-0.00354\text{×}16\text{²}$$=4.9838$

2. Undo the log by raising e (about 2.718) to that power, then round to the nearest gram

   $e^{4.9838}$$=146\text{\hspace{0.17em}g}$

3. Find the object nearest in weight, a dollar's worth of nickels (20 coins). Divide the baby's typical weight by its weight to compare them

   $\frac{146\text{\hspace{0.17em}g}}{100\text{\hspace{0.17em}g}}$$=1.46$

4. The ratio is between 0.67 and 1.5, so the two weigh about the same. That makes it a fair match

   $1.46\text{is within 1.5 times either way →}\text{A dollar's worth of nickels (20 coins)}$

4. Closest object by weight: A dollar's worth of pennies (100 coins)

1. A due date is 280 days after the first day of the last period, so count back 280 days to find that starting day

   $\text{Oct 20, 2025}\text{−}280\text{\hspace{0.17em}days}$$=\text{Jan 13, 2025}$

2. Count the days from the first day of the last period to the counting-from date

   $\text{May 13, 2025}\text{−}\text{Jan 13, 2025}$$=120\text{\hspace{0.17em}days}$

3. Split the days into whole weeks and leftover days, since pregnancy is counted in weeks

   $120\text{÷ 7}$$=\text{17 weeks, 1 day}$

4. Put week 17 into the Hadlock formula for typical weight. The answer is the natural log (ln) of the weight in grams

   $0.578\text{+}0.332\text{×}17-0.00354\text{×}17\text{²}$$=5.1989$

5. Undo the log by raising e (about 2.718) to that power, then round to the nearest gram

   $e^{5.1989}$$=181\text{\hspace{0.17em}g}$

6. Find the object nearest in weight, a dollar's worth of pennies (100 coins). Divide the baby's typical weight by its weight to compare them

   $\frac{181\text{\hspace{0.17em}g}}{250\text{\hspace{0.17em}g}}$$=0.72$

7. The ratio is between 0.67 and 1.5, so the two weigh about the same. That makes it a fair match

   $0.72\text{is within 1.5 times either way →}\text{A dollar's worth of pennies (100 coins)}$

5. Closest object by weight: A half gallon of water

1. Put week 32 into the Hadlock formula for typical weight. The answer is the natural log (ln) of the weight in grams

   $0.578\text{+}0.332\text{×}32-0.00354\text{×}32\text{²}$$=7.577$

2. Undo the log by raising e (about 2.718) to that power, then round to the nearest gram

   $e^{7.577}$$=\mathrm{1,953}\text{\hspace{0.17em}g}$

3. Find the object nearest in weight, a half gallon of water. Divide the baby's typical weight by its weight to compare them

   $\frac{\mathrm{1,953}\text{\hspace{0.17em}g}}{\mathrm{1,891.48}\text{\hspace{0.17em}g}}$$=1.03$

4. The ratio is between 0.67 and 1.5, so the two weigh about the same. That makes it a fair match

   $1.03\text{is within 1.5 times either way →}\text{A half gallon of water}$

6. Closest object by weight: A 12-ounce can of soda

1. Put week 20 into the Hadlock formula for typical weight. The answer is the natural log (ln) of the weight in grams

   $0.578\text{+}0.332\text{×}20-0.00354\text{×}20\text{²}$$=5.802$

2. Undo the log by raising e (about 2.718) to that power, then round to the nearest gram

   $e^{5.802}$$=331\text{\hspace{0.17em}g}$

3. Find the object nearest in weight, a 12-ounce can of soda. Divide the baby's typical weight by its weight to compare them

   $\frac{331\text{\hspace{0.17em}g}}{370\text{\hspace{0.17em}g}}$$=0.89$

4. The ratio is between 0.67 and 1.5, so the two weigh about the same. That makes it a fair match

   $0.89\text{is within 1.5 times either way →}\text{A 12-ounce can of soda}$

7. Closest object by weight: A dollar's worth of nickels (20 coins)

1. Count the days from the first day of the last period to the counting-from date

   $\text{Apr 12, 2025}\text{−}\text{Jan 11, 2025}$$=91\text{\hspace{0.17em}days}$

2. Split the days into whole weeks and leftover days, since pregnancy is counted in weeks

   $91\text{÷ 7}$$=\text{13 weeks, 0 days}$

3. Put week 13 into the Hadlock formula for typical weight. The answer is the natural log (ln) of the weight in grams

   $0.578\text{+}0.332\text{×}13-0.00354\text{×}13\text{²}$$=4.2957$

4. Undo the log by raising e (about 2.718) to that power, then round to the nearest gram

   $e^{4.2957}$$=73\text{\hspace{0.17em}g}$

5. Find the object nearest in weight, a dollar's worth of nickels (20 coins). Divide the baby's typical weight by its weight to compare them

   $\frac{73\text{\hspace{0.17em}g}}{100\text{\hspace{0.17em}g}}$$=0.73$

6. The ratio is between 0.67 and 1.5, so the two weigh about the same. That makes it a fair match

   $0.73\text{is within 1.5 times either way →}\text{A dollar's worth of nickels (20 coins)}$

8. Closest object by weight: A stack of 10 sheets of printer paper

1. Put week 12 into the Hadlock formula for typical weight. The answer is the natural log (ln) of the weight in grams

   $0.578\text{+}0.332\text{×}12-0.00354\text{×}12\text{²}$$=4.0522$

2. Undo the log by raising e (about 2.718) to that power, then round to the nearest gram

   $e^{4.0522}$$=58\text{\hspace{0.17em}g}$

3. Find the object nearest in weight, a stack of 10 sheets of printer paper. Divide the baby's typical weight by its weight to compare them

   $\frac{58\text{\hspace{0.17em}g}}{45.36\text{\hspace{0.17em}g}}$$=1.28$

4. The ratio is between 0.67 and 1.5, so the two weigh about the same. That makes it a fair match

   $1.28\text{is within 1.5 times either way →}\text{A stack of 10 sheets of printer paper}$

9. Closest object by weight: A gallon of water

1. A due date is 280 days after the first day of the last period, so count back 280 days to find that starting day

   $\text{Jan 2, 2027}\text{−}280\text{\hspace{0.17em}days}$$=\text{Mar 28, 2026}$

2. Count the days from the first day of the last period to the counting-from date

   $\text{Dec 28, 2026}\text{−}\text{Mar 28, 2026}$$=275\text{\hspace{0.17em}days}$

3. Split the days into whole weeks and leftover days, since pregnancy is counted in weeks

   $275\text{÷ 7}$$=\text{39 weeks, 2 days}$

4. Put week 39 into the Hadlock formula for typical weight. The answer is the natural log (ln) of the weight in grams

   $0.578\text{+}0.332\text{×}39-0.00354\text{×}39\text{²}$$=8.1417$

5. Undo the log by raising e (about 2.718) to that power, then round to the nearest gram

   $e^{8.1417}$$=\mathrm{3,435}\text{\hspace{0.17em}g}$

6. Find the object nearest in weight, a gallon of water. Divide the baby's typical weight by its weight to compare them

   $\frac{\mathrm{3,435}\text{\hspace{0.17em}g}}{\mathrm{3,782.96}\text{\hspace{0.17em}g}}$$=0.91$

7. The ratio is between 0.67 and 1.5, so the two weigh about the same. That makes it a fair match

   $0.91\text{is within 1.5 times either way →}\text{A gallon of water}$

10. Closest object by weight: A stack of 10 sheets of printer paper

1. A due date is 280 days after the first day of the last period, so count back 280 days to find that starting day

   $\text{Oct 23, 2025}\text{−}280\text{\hspace{0.17em}days}$$=\text{Jan 16, 2025}$

2. Count the days from the first day of the last period to the counting-from date

   $\text{Apr 5, 2025}\text{−}\text{Jan 16, 2025}$$=79\text{\hspace{0.17em}days}$

3. Split the days into whole weeks and leftover days, since pregnancy is counted in weeks

   $79\text{÷ 7}$$=\text{11 weeks, 2 days}$

4. Put week 11 into the Hadlock formula for typical weight. The answer is the natural log (ln) of the weight in grams

   $0.578\text{+}0.332\text{×}11-0.00354\text{×}11\text{²}$$=3.8017$

5. Undo the log by raising e (about 2.718) to that power, then round to the nearest gram

   $e^{3.8017}$$=45\text{\hspace{0.17em}g}$

6. Find the object nearest in weight, a stack of 10 sheets of printer paper. Divide the baby's typical weight by its weight to compare them

   $\frac{45\text{\hspace{0.17em}g}}{45.36\text{\hspace{0.17em}g}}$$=0.99$

7. The ratio is between 0.67 and 1.5, so the two weigh about the same. That makes it a fair match

   $0.99\text{is within 1.5 times either way →}\text{A stack of 10 sheets of printer paper}$