Electricity, nutrients, soil, seeds and the kit itself — see what a gram actually costs you. Free, no sign-up, in your own currency.
What this cycle cost
Kit, spread across several cycles
What you got out of it
What counts is the dry weight, not what comes off the plant at harvest — there is a factor of four to five between them. The electricity figure for a cycle comes from the electricity cost calculator. Under “kit” goes everything that survives more than one cycle: tent, light, fan, pots, meters.
per gram, with the kit counted proportionally
| Setup | Yield | Total | Per gram |
|---|---|---|---|
| Small (100 W) | 90 g | € 154.80 | € 1.72 |
| Medium (240 W) | 216 g | € 292.56 | € 1.35 |
| Large (480 W) | 432 g | € 531.88 | € 1.23 |
Worked out at 0.9 grams per watt, the electricity price preset in the electricity calculator, and a kit that lasts ten cycles. The bigger the tent, the cheaper the gram — the kit and the baseline load spread across more yield. With your own figures the calculator above is more accurate.
These calculators give you reference values for your own judgement. They replace neither a measurement on site nor expert advice — all figures without guarantee.
Most estimates stop at electricity. It is the largest running item, but it is only about half the bill. In full there are six: electricity, nutrients, soil or substrate, seeds or clones, sundries and a share of the kit.
Added up they give you the cost of one cycle. Divided by the dry yield they give you the figure that actually matters: the price per gram. Only that one compares honestly between two cycles — a total on its own says nothing without the yield beside it.
A medium tent with a 240-watt light comes to roughly € 142 in electricity over 90 days, plus about € 100 for nutrients, soil, seeds and sundries, plus € 50 as this cycle's share of the kit. That is € 292 for one cycle. At 216 grams dry, it works out at € 1.35 per gram — or € 38.32 an ounce.
This is where estimates diverge, and they do it in both directions. Half of them put tent, light and fan entirely into the first cycle — which makes the first gram cost € 3.44 and growing look expensive. The other half leave the kit out altogether, which makes it look cheaper than it is.
Both are wrong, and the fix is the one every business applies to its machinery: depreciate it. The purchase price is divided by the number of cycles it is expected to last. A € 500 kit that survives ten cycles costs a single cycle € 50 — not € 500, and not nothing.
How many cycles to assume is an honest estimate, not a science. Ten cycles at two or three harvests a year is around four years — conservative for a tent and a fan, optimistic for a budget LED. If you are unsure, run it once with five and once with fifteen and see how much it moves the result. Usually less than you would think.
All the attention goes on the costs, yet the denominator decides the result just as much. And that is where the expensive mistake happens: wet weight instead of dry weight.
There is a factor of four to five between them. Weigh 1,000 grams straight off the plant and use that, and you get a fifth of the real price per gram. What is left after drying is typically 200 to 250 grams. What it will be for you is what the yield calculator works out from the wet weight.
Second point on the denominator: only what you keep counts. Leaf that goes in the trim bin and anything that moulds is not yield. The figure that belongs in the calculator is what sits in the jar after drying and trimming.
Across a cycle, electricity is the largest single item in almost any setup, usually half to two thirds of the running costs. In the example above it is € 142 out of € 242.
The figure is not on your bill; it has to be worked out: wattage times hours times days times price, and separately for light and fan, because the fan runs around the clock. That is what the electricity cost calculator does — its result goes into the first field above.
One note that saves money here: the wattage on an LED box is rarely the real one. A light sold as “600 W” often draws 100 to 150 watts. Work with the advertised figure and you overstate your electricity — and with it the price per gram.
Nutrients are almost always overestimated. The bottles look expensive but go a long way: a set at € 40 to € 60 usually covers several cycles, because dosing runs in millilitres per litre of water. For a single cycle you tend to land at € 20 to € 40.
Soil is a consumable and comes round every time, roughly € 15 to € 30 a cycle for three or four plants. Growing hydroponically swaps this item for nutrient solution and medium — the order of magnitude stays similar.
Seeds have the widest spread of all: from a few euros to over twenty each. Clones taken from your own mother plant cost next to nothing beyond a little electricity and time — they are the only way to bring this item down to near zero for good.
Under sundries goes everything small that otherwise disappears quietly: pots, saucers, netting, pH drops and calibration fluid, replacement filters, trimming scissors. Unremarkable one by one, € 10 to € 30 a cycle together.
The table above shows something that runs against intuition at first: the bigger the setup, the cheaper the gram. Small comes to € 1.72, medium to € 1.35, large to € 1.23 — even though the total more than triples.
The reason is the items that do not scale with size. An exhaust fan draws much the same in a small tent as in a large one. A tent does not cost proportionally more per square metre. And a cycle takes the same time either way. Those fixed costs spread across more yield — which is exactly what brings the price per gram down.
That does not mean bigger is always better. The effect only works if the space is actually filled. A 480-watt light over two plants draws the same power as over six and returns a fraction of the yield — at which point the maths flips. Using the full footprint is the strongest lever on cost per gram, and it costs nothing.
Before your first cycle any cost calculation is an estimate — you do not know your yields yet, nor your own consumption. The calculator above answers the question up front, well enough to decide on.
It gets honest once there are real figures behind it. And that takes someone writing things down: which purchase belonged to which cycle, how much power went through in which period, what was left dry at the end. By hand that is tedious, which is why hardly anyone does it — the figure everyone wants is the one nobody records.
In the CRIS app it happens as you go: purchases land on the right cycle, the feeding schedule works out what was used, the tent depreciates proportionally over time, and the harvest is in the journal anyway. At the end the cost overview shows your own price per gram — and the analysis shows whether this cycle came out cheaper than the last.
In a medium tent with a 240-watt light it comes to around € 1.35 a gram with the kit counted proportionally — about € 38 an ounce. A small tent lands closer to € 1.72, a large one at € 1.23. The spread comes mainly from the yield and the electricity price, so put your own figures into the calculator above.
Yes, but proportionally. Putting the whole purchase into the first cycle makes that first gram artificially expensive; leaving it out flatters the figure. The right way is to divide it by the number of cycles it lasts — a € 500 kit over ten cycles costs a single cycle € 50.
Ten cycles is a workable starting point — at two or three harvests a year that is about four years. For a tent, pots and a fan that is on the cautious side; for a budget LED it is optimistic. If you are unsure, run it once with five and once with fifteen: the difference in cost per gram is usually smaller than expected.
Dry weight only. There is a factor of four to five between the two: 1,000 grams of freshly cut material typically comes down to 200 to 250 grams dry. Put the wet weight in and you get a fifth of the real price per gram.
The exhaust fan, because it runs around the clock and still looks small. The sundries — pots, netting, pH drops, calibration fluid, replacement filters — because they arrive in many little amounts. And the kit, because it is not felt during the cycle itself.
Because the whole purchase sits in it with no yield beside it yet. Put tent, light and fan entirely into the first cycle and you easily land at € 3.44 a gram instead of € 1.35. From the second cycle on only the running costs remain — € 1.12 a gram in the example above.
The yield, not the costs. Filling the footprint under the light costs nothing and works straight away: the same light draws the same power over two plants as over six. After that come a more efficient light when you next buy, a controlled rather than continuously running fan, and clones instead of bought seeds.
Yes, with the same six items. What differs is where the figures come from: in the app they come from recorded purchases, the feeding schedule, the tent depreciating over time and the harvest you entered — rather than from an estimate. The calculator here answers the question up front; the app answers it afterwards with your real figures.
In the CRIS app purchases, electricity, nutrients and the kit's share land on the right cycle automatically — at the end you see what a gram really cost you, and the analysis shows whether the last cycle came out cheaper than the one before. Offline, no account.