🍶 Ink Bottle Life Calculator
Find out how many refills, pages, days, and years a bottle of ink will give you at your own writing pace — and why one bottle can last so long.
🍶 How long the bottle lasts
A planning estimate at 0.005 mL of ink per page. Wetter or broader nibs empty a bottle far faster, and some ink is always lost to cleaning and flushing between colours.
One bottle, a very long time
Fountain-pen ink is bought by the bottle and used by the drop. Because a page takes only a few thousandths of a millilitre, even a modest bottle holds thousands of pages of writing — which is why so many pen lovers end up with more ink than they can realistically finish.
The maths is simple: refills are the bottle divided by your pen’s capacity, pages are the bottle divided by ink per page, and days are pages divided by how much you write. Change any one and the timeline shifts — a broad nib or a daily journaling habit will empty a bottle far sooner than an occasional fine-nib note.
❓ Frequently Asked Questions
How long does a bottle of fountain-pen ink last?
Usually a very long time. A standard 30–50 mL bottle holds enough ink for thousands of pages, so at typical writing volumes it can last years — often outliving the pen you bought it for. Enter your bottle size, pen capacity, and pages per day to see your own figure.
How many times can I refill my pen from one bottle?
Divide the bottle volume by how much your pen holds per fill. A converter or piston filler holds roughly 0.6–1.5 mL, so a 50 mL bottle gives somewhere between about 30 and 80 fills — before accounting for the ink lost to cleaning between colours.
Why is my ink running out faster than the estimate?
Broad, wet, or flex nibs lay down far more ink per page than the fine-nib default of 0.005 mL. Flushing the pen when you change colours also wastes ink. If a bottle empties quickly, raise the ink-per-page figure or your pages-per-day to match reality.
Does ink go bad before I finish the bottle?
Well-kept ink lasts many years, but it isn't forever — keep bottles capped, cool, and out of sunlight, and watch for mould, sediment, or a strange smell. If a bottle will clearly outlast its shelf life at your pace, a smaller bottle or sharing with friends avoids waste.