Practical
Tools and calculators
30 tools for the arithmetic cider actually requires — and for the words on the label that the arithmetic cannot help with.
Every calculation here shows its workings and states its assumptions. Several of them are models fitted to rules of thumb rather than measurements, and where that is true the result says so rather than hiding it in a footnote. Nothing is sent anywhere: the arithmetic runs in your browser.
Priming sugar and bottle pressure are not abstractions. Over-pressurised glass bottles fail by shattering, and the commonest cause is priming a cider that had not actually finished fermenting. Both tools give the resulting pressure alongside the sugar figure, and both say what common bottles and closures will hold.
Strength and alcohol
Gravity, alcohol, units and duty.
ABV from gravity
How strong did my cider turn out?
Alcohol by volume from a starting and finishing hydrometer reading, with both of the formulas in common use shown side by side — because they disagree above about 1.070 and most calculators only give you one of them.
Alcohol units
How many units is this?
UK units and grams of pure alcohol for any serving, with the US standard drink shown alongside — because the two measures differ and advice written for one country does not transfer.
Potential alcohol
How strong will this juice ferment out to?
The ceiling a juice can reach if it ferments dry, with the finishing gravity exposed as an input rather than assumed — because a perry does not finish where a cider does, and sorbitol is the reason.
Brix to specific gravity
What does my refractometer reading mean in SG?
Converts a refractometer reading to specific gravity, and says clearly why the reading stops being trustworthy the moment fermentation begins.
Hydrometer temperature correction
My cider was not at 20 °C — is my reading wrong?
Corrects a hydrometer reading taken away from the instrument’s calibration temperature. A warm sample reads low and a cold one reads high, and at fifteen degrees off the error is bigger than the change most readers are trying to detect.
Attenuation
How far has my fermentation actually gone?
What proportion of the available sugar the ferment has taken, and why a dry cider reads over 100% on this scale while a perry reads low without having stalled.
Duty on a batch
How much duty will I owe on this?
How the charge is worked out — on litres of pure alcohol, so strength matters more than volume. You supply the current rate: CiderHQ does not publish one, because a rate hard-coded here would be quietly wrong within a year.
Litres of pure alcohol
How much pure alcohol is in this batch?
The figure duty is charged on in the UK and many other jurisdictions, by volume and by mass.
Specific gravity to Brix
What is my hydrometer reading in Brix?
The inverse conversion, for working with analyses and suppliers that report sugar in degrees Brix.
Fruit and yield
How much fruit, how much juice, how many bottles.
Fruit for a target volume
How many apples do I need?
The same relationship inverted, with a rough count of actual apples as well as a weight.
Juice from fruit
How much juice will this fruit give me?
Juice from a weight of fruit, with yields for each press type — because yield is a property of the press at least as much as of the fruit.
Bottle count
How many bottles will this batch fill?
Bottles from a batch volume, with a realistic allowance for what is lost at racking and in the filler.
Cultivar comparison
How do these cultivars compare?
Compare cider apples or perry pears on the figures a single study measured, with each one’s standing among the others that study analysed — and the other studies’ figures shown apart rather than merged.
Topping-up reserve
How much cider will I lose, and how much should I hold back?
What racking costs across a batch, and therefore how much to keep aside so vessels can be kept full. Headspace is the first-named cause on the volatile acidity record and appears in the prevention list of three more faults; this is the arithmetic that lets you see the problem in September rather than in March.
Orchard yield
How much fruit will my orchard crop?
Fruit from an area of orchard, by orchard system — and an honest account of why this is the least predictable number in cider.
Carbonation and pressure
Priming, conditioning, and the pressure that results.
Bottle pressure
Is this bottle going to be safe?
The pressure a given carbonation level reaches at a given temperature, against what common closures and bottles will actually hold.
Priming sugar
How much sugar to carbonate this?
Priming sugar for a target carbonation, accounting for the CO₂ the cider already holds — and the pressure the result will reach, which is the half of the answer most calculators leave out.
Blending
What a blend will be, and which way changing it pushes.
Blend explorer
What will this mix of apples give me?
Pick cultivars, set proportions, and see which way the blend moves on acid, tannin, sugar and body — with the evidence behind each cultivar shown, and the limits of the model stated rather than hidden.
Acid blending
How much sharp juice do I need to add?
The acid a blend will land on, and what proportion of sharp fruit gets you to a target — an arithmetic question with a microbiological answer behind it.
Blend arithmetic
What strength will my blend be?
Volume-weighted alcohol, acid or gravity across several batches, with each component shown as a share of the whole.
Dilution
How much water do I need to add?
Water to bring a strength down, and a reminder that it brings acid, tannin, sugar and aroma down in exactly the same proportion.
Chemistry
Acid, sulphite and the numbers that govern them.
Juice analysis interpreter
What do my juice readings actually mean?
Place your own gravity, Brix, pH, acid and nitrogen readings against measurements recorded with their orchard, period and source — with what each figure means for the ferment, and no dose for any of it.
Molecular SO₂
Is my sulphite actually doing anything?
The active fraction of free sulphur dioxide at a given pH — the relationship that explains why a low-acid bittersweet juice is genuinely hard to protect, and why blending in sharp fruit is a microbiological decision.
Titratable acidity
What does my titration reading mean?
Turns a burette reading into an acidity figure — and gives it in all three conventions at once, because the same cider is reported as malic acid in Britain, as sulphuric acid in older French practice and as tartaric acid by anything that came from winemaking. The three differ by up to a third.
Sugar addition
How much sugar to reach my target gravity?
Sugar needed to raise a juice to a target gravity, the alcohol it adds, and a note on where adding it is restricted.
Reference
Decoders and lookups rather than calculations.
Fault finder
Something is wrong with my cider — what is it?
Describe what you can smell, taste and see, and this narrows it to the faults that match, with the mechanism, the likely cause, and an honest answer about whether it can be put right.
Label decoder
What is this label actually telling me?
What the terms on a cider or perry label mean in the UK, France, Spain, Germany and the United States — and which of them are legally defined, which are protected, and which mean nothing at all.
Sweetness decoder
What does "dry" mean on this label?
Dry, medium, sweet, brut, doux, demi-sec, seco, halbtrocken — what each word means, in the system that defines it. There is no single sweetness ladder, and this explains why the words contradict each other across borders.
Serving temperature
How cold should I serve this?
Serving ranges by style, derived from each style’s own sensory profile, with the reason temperature changes what you taste.
Tasting note builder
How do I write down what I am tasting?
Builds a structured note from the site’s own vocabulary — conditions first, every descriptor with an intensity, suspicion kept apart from observation — and names what the note is still missing. No score field, and there will not be one.
Where the number comes from
A calculator assumes you already have a reading. These say how to obtain each one, what it actually detects, and the specific ways it is commonly taken wrongly.
- What to measure, and what each number tells you — gravity, temperature, pH, titratable acidity and free sulphur dioxide, each with its characteristic failure mode.
- Your first batch of cider — where each of these readings is taken in practice, and which of them cannot be recovered if missed.
- Working safely: pressure, fruit and gas — why the priming and pressure tools exist, and what the arithmetic is protecting against.
What is deliberately not here
Duty rates. The duty tool asks you for the current rate rather than carrying one. Rates change at fiscal events, and a figure hard-coded into a web page is quietly wrong within a year while continuing to look authoritative.
Additive dosages. The sulphite tool tells you what a measured free SO₂ figure amounts to at your pH. It does not tell you how much to add, because that is a food-safety decision governed by legal limits and by the juice in front of you, and it belongs to your supplier’s or regulator’s guidance rather than to a general reference.
Anything that estimates whether you are fit to drive. No calculator can do that, and one that appears to would be dangerous.