How ConvertSnap Converts
Every definition, every source, and the places where a conversion is genuinely ambiguous. A converter is only worth using if you can check it.
Who makes this
ConvertSnap is built and maintained by a small independent team and published under the organisation's name. We do not claim expert credentials. What we claim is narrower and verifiable: the conversion factors below are the exact values defined by the international standards bodies, and we name them so you can check.
Unit conversions — exact by definition
Most imperial-to-metric conversions are not approximations. They are exact definitions set by international agreement and published by NIST and the BIPM. We use the exact values, then round only for display.
| Conversion | Exact defined value |
|---|---|
| Inch to centimetre | 1 in = 2.54 cm, exactly |
| Pound to kilogram | 1 lb = 0.453 592 37 kg, exactly |
| Mile to kilometre | 1 mi = 1.609 344 km, exactly |
| US gallon to litre | 1 gal = 3.785 411 784 L, exactly |
| Fluid ounce (US) to millilitre | 1 fl oz = 29.573 529 562 5 mL, exactly |
Temperature
Celsius and Fahrenheit are interval scales with different zero points, which is why you cannot convert a temperature difference the same way you convert a temperature. A 10°C rise is an 18°F rise, not 50°F.
Digital storage
This is the conversion people get wrong most often, and both answers are right depending on which system you mean. Decimal (SI) prefixes are powers of 1000; binary (IEC) prefixes are powers of 1024.
Drive manufacturers use decimal; most operating systems report binary. That is the entire reason a "1 TB" drive shows as about 931 GB.
Currency — where the rates come from
Live rates are fetched from the Frankfurter API, which publishes the European Central Bank's euro foreign exchange reference rates. Non-euro pairs are cross-computed through the euro.
1. ECB reference rates are published once each working day, at around 16:00 CET. They are a daily snapshot, not a live market feed.
2. They are reference rates. No bank will give you this rate. Retail conversion carries a spread and usually a fee.
3. If the live fetch fails, the converter falls back to a stored rate table so the tool still works offline. Those stored rates are older than the live ones, by definition.
4. There are no ECB reference rates on weekends or ECB holidays; the last working day's rates carry over.
Use this for estimating, not for accounting, invoicing or trading.
Percentages
Percentage points are not percentages. A rate going from 4% to 6% is a rise of two percentage points and a 50% increase. Both statements are true and they mean different things.
Dates
Date arithmetic uses the proleptic Gregorian calendar and ISO 8601 conventions, counting whole days. Leap years follow the standard rule: divisible by 4, except centuries, unless divisible by 400.
Passwords
Strength is reported as entropy in bits — the base-2 logarithm of the number of possible passwords, given the character set and length actually used:
Crack-time estimates are illustrative arithmetic: entropy divided by an assumed guessing rate. Real attack speed depends entirely on how the target stored the password — a modern slow hash and an unsalted MD5 differ by many orders of magnitude — so treat any crack-time figure, ours included, as a rough comparison between passwords rather than a prediction.
Our guidance follows NIST's Digital Identity Guidelines, which are worth reading if you set password policy: NIST recommends length over composition rules, says verifiers should not impose character-mixing requirements, and says passwords should not be rotated arbitrarily on a schedule — only on evidence of compromise.
What ConvertSnap is not
Not authoritative for regulated use. For anything legal, financial or safety-critical, use the primary standard or a certified source, not a free web tool.
Not collecting your inputs. Every tool runs in your browser. The only network call any tool makes is the exchange-rate fetch, which sends a currency pair and nothing else.
Not free of commercial interest. The site carries advertising. Ads pay for it. They have no influence on which standards we follow or what these pages say.
Corrections
If a factor here is wrong, a formula is misapplied, or a source does not say what we claim it says, tell us on the contact page — name the page and the number. We check it against the standard, fix it, and log the correction here.
Last reviewed: 8 September 2026.
References
- National Institute of Standards and Technology. Guide for the Use of the International System of Units (SI), NIST Special Publication 811. nist.gov Accessed 8 Sep 2026.
- Bureau International des Poids et Mesures. The International System of Units (SI Brochure). bipm.org Accessed 8 Sep 2026.
- National Institute of Standards and Technology. Prefixes for binary multiples. physics.nist.gov Accessed 8 Sep 2026.
- European Central Bank. Euro foreign exchange reference rates. ecb.europa.eu Accessed 8 Sep 2026.
- Frankfurter. Exchange rates API built on ECB reference rates. frankfurter.dev Accessed 8 Sep 2026.
- National Institute of Standards and Technology. SP 800-63B, Digital Identity Guidelines: Authentication and Lifecycle Management. pages.nist.gov Accessed 8 Sep 2026.
- International Organization for Standardization. ISO 8601 date and time format. iso.org Accessed 8 Sep 2026.