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Redmoon Converters

Changes and corrections

When a tool gives a wrong answer, the fix is listed here with the old number and the new one. New guides and changes to how the site works are listed here too.

Last updated: October 12, 2026

Every calculator on this site is a small program, and small programs have bugs. The ones that matter are those that hand you a confident number that is wrong, such as a generator one size too small or a priming dose that leaves the beer flat. We look for those by reading each tool's code against the standard or formula it claims to follow and re-deriving its output by hand. When we find one, it goes on this page. If you find one we missed, the contact page explains what to send, and the fix will be listed here.

October 12, 2026: eleven tools and seventeen guides corrected

Writing guides that use several tools at once means checking each tool against its page and its older guides side by side. That turned up these. Two came from our own earlier corrections: the August canning change that we have now reversed, and guides that were never updated when the tools behind them were fixed.

ToolWhat was wrongWhat it does now
Fertilizer / Nutrient Dilution Calculator Presets were labelled as meter (TDS) readings but solved for nitrogen, phosphorus and potassium only. A meter reads about twice that, so the heavier presets mixed roughly 2.3× too much concentrate. Presets are now honest N-P-K targets (150 to 600 ppm) that land inside the EC ranges the tool quotes, and the EC line says it counts N-P-K only.
Day Rate to Annual Salary Calculator Salary to day rate added a leave uplift on top of billable days that already excluded leave, pricing the same time off twice. A 100,000 salary over 200 billable days now needs 500 a day, not 550. The redundant leave field is gone.
Canning Altitude Adjustment Calculator Doubled the boiling-water addition for processes over 20 minutes and credited that to USDA. No USDA or NCHFP table says so; it was introduced by our own August change. Back to USDA’s general +5/+10/+15/+20 table, with a clear instruction to follow a tested recipe’s own altitude rows when it has them. It erred toward over-processing, not under.
Video Bitrate & File Size Calculator The “ProRes 4444” row held ProRes 422 HQ rates, 4K and 1080p used different frame-rate bases, and 60p was scaled ×1.5 for a codec where every frame is stored whole. Rates follow Apple’s ProRes white paper on one 30p basis and scale with frame rate: 1080p 4444 is 330 Mbps (was 220), 4K 422 is 589 Mbps (was 492), and 4K60 422 is about 530 GB an hour (was 330).
Recipe Scaler — Scale Ingredients by Servings Read “4½ cups” as 4, printing “3 ¼½ cups” at 0.8× and skipping the metric conversion. Attached fractions now parse: 0.8 × 4½ cups is 3⅝ cups (864 ml), and “1½-2 cups” doubled is 3-4.
Cron Expression Builder & Translator Rewrote every 7 in the day-of-week field to 0, so the valid range 5-7 failed, and left UTC out of the time-zone menu in Chromium browsers. 7 now means Sunday anywhere (5-7 is Friday to Sunday), and UTC is always listed.
Priming Sugar Calculator The dropdown still showed the old honey (0.93) and maple (1.14) factors after the maths was corrected in August, and the temperature box kept °F limits in °C mode. Labels show 1.11 and 1.38, matching what the tool computes, and the limits follow the unit.
Color Converter — HEX, RGB, HSL, OKLCH & Contrast Silently clipped colours outside the sRGB gamut, including wide-gamut OKLCH input. It still converts to sRGB, and now says so under the result when it had to clip.
Oven Temperature Converter The description promised high-altitude adjustments the tool does not have, and the chart listed gas 9 as 245 °C plus a gas 10. The claim is gone and the chart matches the converter (gas 9 = 240 °C). Altitude baking is covered in a guide instead.
Generator Sizing Calculator The result sentence called the total starting load a “starting surge”. It now says the total is what the generator must supply while the biggest motor starts.
3D Print Total Cost Estimator The headline price was labelled “Etsy-ready” although marketplace fees are not included. The sticker calculator said the same. Both now say the price is before marketplace fees. A new guide shows how to add fees on top.

Guides corrected the same day, each now showing an “Updated” date:

October 12, 2026: a regular publishing schedule

New guides now come out on a fixed schedule, twice a week, instead of in batches. The first three went out today. Each one covers a whole job that crosses several tools, such as getting through a power cut, pricing handmade goods, or cooking an American recipe in a metric kitchen. Single-tool explainers already exist for all 94 tools. The sitemap now reports the date each page actually changed, not the date the site was last rebuilt. This page was added too.

September 7, 2026: crawlers can see the site as you do

A line in robots.txt, there since launch, stopped search engines from loading the site's stylesheets and calculator scripts. To a person nothing looked wrong. To a crawler every page was unstyled and every tool was inert. The line was removed. Advertising code was also taken off pages that have no content of their own (the 404 page, Contact, Privacy and the category lists), and ads on tool pages and guides now sit below the content instead of between the heading and the tool. Guides now carry their author's name.

August 27, 2026: every tool page explains its limits

Each of the 94 tool pages gained a longer explanation written from the tool's own code. It covers what the tool assumes, where its model stops being accurate, a worked example with real numbers, and the mistakes people make most often with that kind of calculation.

August 26, 2026: a full re-check, and sources on every tool that uses one

Every tool was re-checked against what its code computes, and each tool page now shows the date of that check. The 24 tools that rely on something external now cite it: a published standard (ISO 216 paper sizes, sRGB, POSIX cron), a named formula (Epley, Mifflin-St Jeor, Tinseth) or a rate that someone else sets. Those last ones, like the IRS mileage rate, are marked as figures that change, so you know to check them. The 18 category pages gained a short guide to choosing between their tools.

August 17, 2026: twenty calculators corrected

A line-by-line audit of all 94 tools found defects in most of them. Many were small: a label without a unit, or a control that did nothing. The ones below changed a number you would have relied on. Eleven tools came back clean, among them the Wilks/DOTS scorer, the colour converter and the password entropy estimator.

ToolWhat was wrongWhat it does now
Generator Sizing Calculator Chose which appliance to add starting surge for by its total surge, not by how much its surge exceeds its running draw. It undersized the generator. Space heater plus washer: starting load 2,000 W → 3,000 W, suggested unit 3 kW → 4 kW. Loads above the largest standard size are no longer silently capped.
Fence Post Concrete & Spacing Calculator Filled the whole hole with concrete, ignoring the post standing in it. Added a post-size input. The default run went from 41 bags to 35 (about 15% less).
Priming Sugar Calculator Honey and maple syrup factors were too low for their fermentable fraction, so they under-primed. Honey 108 g → 129 g, maple 133 g → 161 g for the same batch.
Running Pace Converter & Race Time Predictor Pace mode quietly assumed you had held that pace for 5 km, then predicted every race from it. Added a “held for” distance. A goal marathon pace now predicts 211.0 min, not 239.8.
Freelance Hourly to Project Rate Calculator The effective hourly rate divided by the quoted hours and ignored the revision hours already priced in. Default effective rate 144 → 125.22 per hour worked.
Tile & Flooring Coverage Calculator Read the grout gap as millimetres even in imperial mode. A ⅛ in gap is now 3.17 mm, not 0.125 mm, so tile counts no longer run short.
Fermentation Brine & Salt Calculator Used one grams-per-tablespoon figure for every salt, contradicting the page’s own warning about Diamond Crystal. Added a salt-type selector, from 9 g/tbsp (Diamond Crystal) to 18 g/tbsp (table salt).
Canning Altitude Adjustment Calculator The dial-gauge table stopped at 14 lb and called that the highest band. Extended to USDA’s 15 lb band for 8,001–10,000 ft. (A boiling-water change made at the same time was itself wrong; see 12 October.)
BTU & HVAC Sizing Calculator Heating mode reused the cooling multipliers, so a cold climate needed less heat than a hot one. Same room: cold zone now 8,360 W, hot zone 5,720 W. Occupant and kitchen heat is subtracted in heating mode.
ABV Calculator The calorie formula was wrong by roughly a factor of eight. 12 oz at the defaults: 24 kcal → 195 kcal. Added a refractometer correction and a real-extract row.
Bra Size Converter The cup ladder started four letters too low (a 10 cm difference read as AA, not D), and the AU band offset was wrong. Rebuilt on one cup per inch. The default 75/91 cm now gives 30DDD/E, not 30B, and AU bands use the −20 offset brand charts use.
Exposure Triangle Calculator The aperture branch had its sign reversed. f/4 → f/5.6 now asks for ISO 200 from ISO 100, not ISO 50.
Shoe Size Converter Modelled US sizes as one per centimetre, while the barleycorn system they follow is one per third of an inch. Rebuilt on the barleycorn scale. 26 cm now gives US 8, not 7.5.
Barbell Plate Loading Calculator Its greedy fill missed exact combinations, and in lb mode the 45 lb and 35 lb bars were weighed as 44.09 and 33.07. With 15s and 10s, 20 kg per side now loads 10 + 10 instead of reporting 10 kg short. Bar weights are exact in both units.
Recipe Scaler — Scale Ingredients by Servings Skipped lines containing words like “mushrooms”, “minced” or “pinch”, and mishandled ranges and numbered lists. These lines now scale. The guide that described the old behaviour was rewritten.
Landscaping Material Calculator Two printed bag weights disagreed with the tool’s own densities. Topsoil 40 → 58 lb, wood chips 20 → 33 lb. Volumes were always right.
Horse Hay Calculator Accepted kilograms but answered only in pounds. Outputs and bale weight now follow the unit you choose.
Freelance Currency & Tax-Adjusted Rate Converter The exchange rate was fixed and older than its label claimed. The mid-market rate is now an editable field, so you can use today’s rate.
Unix Timestamp Converter The date picker, day-of-year and ISO-week rows used your browser’s zone, ignoring the zone you picked. All of them follow the selected zone, so they no longer slip a day near midnight.
Wedding & Party Drinks Calculator The non-alcoholic row ignored the drinks-per-hour field, and ice did not depend on how long the event ran. Both now scale with your inputs.

Some findings were claims in the page text that the tool didn't support, such as a feature that wasn't built or a format it couldn't read. Eighteen descriptions were rewritten to match what the tools actually do. Two claims were met by building the feature instead: the LED resistor calculator gained the E48 series, and the IBU calculator gained the Rager formula alongside Tinseth.

The same release made the site English-only. Machine-translated copies of every page in seventeen languages were removed rather than left online. The translations were never reviewed by a person, and the guides behind the tools existed only in English. Old translated addresses redirect to the English page.

July 29, 2026: two calculators that were badly wrong

Both were found while writing the explanation for each tool page, which meant reading every calculation line by line.

  • The lumber board-feet calculator divided by 144 while lengths were in feet. That divisor is right only for inches, so every board-foot and cost figure was one-twelfth of the true value. The default list showed 2.33 board feet and $21.33. The right answer is 28.00 board feet and $256.00.
  • The oven temperature converter added 20 °C for a fan oven when it should have subtracted it, so its headline disagreed with the line beneath it by 40 °C. The label's “−40 °F” was also wrong: a 20 °C difference is 36 °F.

June 2, 2026: hidden fields that weren't hidden

A stylesheet ordering problem left some optional inputs visible when they should have been hidden: the custom-ratio box on the macros calculator, the heart-rate and cycling fields on the training zones tool, and the comparison box on the Wilks scorer. The Unix timestamp converter was also missing UTC from its zone list in some browsers. Both were fixed the day after launch.

New guides by month

Every tool has at least one long-form guide. These are all 107 of them, newest first.

October 2026: 3 guides
August 2026: 2 guides
July 2026: 63 guides
June 2026: 32 guides
May 2026: 7 guides

How corrections are handled

A wrong answer gets fixed in the tool and in its explanation at the same time, and it is recorded here with the old and new numbers. We don't quietly edit the past. If a guide described behaviour that has since changed, the guide is rewritten and shows an “Updated” date under its title. More on how the tools are checked is on the About page.