Bottle math

How long does a bottle really last?

Most dog supplements are dosed by weight, so the same bottle can last a small dog for months and a large dog for a few weeks. Here's how to work out what a bottle really means for yours.

Written by the Goodest Labs teamยท Updated October 2026

Goodest Labs makes dog supplements. This is our own educational page, not independent journalism or a third-party review. It is general information, not veterinary advice.

The Math, Step By Step

  • 1. Full days of supply

    Divide the amount in the bottle by the daily amount from the label, then round down. Only whole days count.

  • 2. What's left over

    If the division isn't exact, a little is left over. It isn't another full day, so don't count it as one.

  • 3. Cost per day

    Divide the price you'd actually pay by the full days of supply. For a monthly view, multiply by 30.

  • 4. More than one dog

    Add up each dog's daily amount first, then divide. Only if the label's directions cover each dog's weight.

A Bigger Dog Gets Through A Bottle Faster

That's why we compare cost per day at your dog's weight, not price per bottle.

Three Questions To Ask Any Brand

What's the serving for my dog's weight?

Look for a weight chart on the label, not just a single "daily serving" line on the front.

How much is in the container?

Check the net amount on the actual label (for a liquid, in mL), not just the product title.

What's the price per day at my dog's serving?

A lower price per bottle can still mean a higher price per day for a large dog.

From Goodest Labs

Goodest Labs Premium Liquid Collagen

At 1 to 3 mL a day, one 60 mL bottle lasts about 20 to 60 days.