The pour over ratio is 1:13 to 1:16 by weight, so 20g of coffee takes 260g to 320g of water. The National Coffee Association publishes that band along with the rest of the recipe: water at 90 to 96 C, 2 to 4 minutes of contact between coffee and water, and a bloom pour of double the coffee weight held for 30 to 45 seconds (NCA). A pour over ratio calculator is that band times your dose, and nothing more complicated than that.
Get your numbers for tonight's brew
Enter dose or water, get the other, with the bloom weight and the published band shown alongside.
Dose to water, across the published band
| Dose | 1:13 (strong end) | 1:15 (middle) | 1:16 (weak end) | Bloom water |
|---|---|---|---|---|
| 15g | 195g | 225g | 240g | 30g |
| 18g | 234g | 270g | 288g | 36g |
| 20g | 260g | 300g | 320g | 40g |
| 22g | 286g | 330g | 352g | 44g |
| 25g | 325g | 375g | 400g | 50g |
| 30g | 390g | 450g | 480g | 60g |
Multiplication from the NCA band. Bloom water is double the coffee weight, as the NCA instructs. The 1:15 column is the middle of the published range, not a separately published recommendation.
Going the other way: from your mug
Most people know their mug before they know their dose. A US fluid ounce of water weighs about 29.5735 grams, so divide the mug's water weight by the ratio to get the dose. A 12 fl oz mug holds about 354.9g of water, which is 22.2g of coffee at 1:16 and 27.3g at 1:13. An 8 fl oz cup is 236.6g of water, or 14.8g to 18.2g of coffee.
Brewed volume comes out lower than water in, because wet grounds keep some of it. Aim the water number, not the cup line.
Temperature and time are not optional inputs
The NCA gives 90 to 96 C, citing SCA Standard 102-2024 for 93 C with a 3 degree tolerance, and 2 to 4 minutes of total contact. Those two do more to your cup than moving from 1:15 to 1:16 does. If a brew at a correct ratio drains in 90 seconds it is under-extracted no matter how carefully you weighed, and the fix is grind, not ratio.
The NCA also instructs cold, filtered water where possible and specifically says to avoid distilled or softened water. Distilled water gives extraction nothing to work with.
What the ratio actually controls
Strength, not extraction. Moving from 1:16 to 1:13 puts more coffee against the same water, so the cup reads heavier. It does not make the coffee sweeter or fix sourness, because those come from how completely the water pulled from the grounds, which is grind, temperature and time. Set ratio for how strong you like it, then leave it alone while you dial the other three.
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A ratio expressed in grams needs a scale, and the pour rate needs a spout you can aim: search gooseneck kettles on Amazon. Links are searches, not stocked listings.
Related reading
FAQ
What is the best pour over coffee to water ratio? The NCA publishes 1:13 to 1:16 by weight. At 20g of coffee that is 260g to 320g of water.
How much coffee for a 12 oz pour over? A 12 fl oz mug holds about 354.9g of water, so 22.2g of coffee at 1:16 or 27.3g at 1:13.
Does changing the ratio fix sour coffee? No. Ratio sets strength. Sourness is under-extraction, which is fixed with a finer grind, hotter water inside the 90 to 96 C range, or a longer contact time within the 2 to 4 minute window.
Sources: the 1:13 to 1:16 ratio, the 93 C plus or minus 3 C temperature attributed to SCA Standard 102-2024, the 2 to 4 minute contact time, the bloom of double the coffee weight held 30 to 45 seconds, and the instruction to avoid distilled or softened water are published by the National Coffee Association at aboutcoffee.org/brewing/pour-over, fetched and cached 2026-08-18. Every water weight and dose in this article is arithmetic from those figures and from 29.5735 grams per US fluid ounce of water.
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