EMS Example:

①First Heavy = 500 grams
②Continued Heavy = 500 grams
③Different countries Different prices

Take the example of the United States:
First Heavy Price = $180 USD
Continued Heavy Price = $75 USD

If goods weight = 1100 grams,
1100 grams = 500 + (500+100) grams
then it costs = 180 + 75 * 2 = $330 USD

HongKong Post Example:

①Not Calculate First Heavy
②Not Calculate Continued Heavy
③Not Distinguish Countries

Just based on 1000 grams = $15.84 USD

If goods weight = 1100 grams,
then it costs = 1100 * (15.84 / 1000) = $17.42 USD

All the prices above are Weight-Cost-Price. Actual price need to add fuel costs, report tariff.