Molarity Calculator - 無料オンライン電卓
Molarity is the number of moles of solute per litre of solution. Find the concentration you have, or the mass to weigh out for the concentration you need.
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NaCl is 58.44. Use the molecular weight calculator for other compounds.
Molarity
1 M
Moles of solute
0.1 mol
Millimolar
1,000 mM
一部のコンテンツはまだ英語で表示されます。
Molarity Calculatorとは
Some math calculations come up often enough that reaching for a formula sheet or spinning up a spreadsheet feels like overkill. The Molarity Calculator handles this one end-to-end: enter your values, get the result, and see the formula beside it so you can verify the working or use it as a reference. The calculation runs in your browser with no sign-up and no internet dependency once the page has loaded.
The formula is shown above the result on purpose - it lets you trace the output back by hand if you ever want to. For the overwhelming majority of real-world inputs, the precision is more than sufficient. Edge cases worth knowing: domain restrictions (like logarithms of non-positive numbers, or division by zero) are flagged clearly, and the Molarity Calculator will tell you when an input doesn't make mathematical sense rather than returning a silent wrong answer.
Molarity Calculatorの使い方（3ステップ）
Choose what to find.
Enter the molar mass and volume.
Enter the mass or target molarity and read the result.
Molarity Calculatorのしくみ
Moles are mass divided by molar mass. Molarity divides moles by the final volume of the solution in litres.
M = moles / litres = (mass / molar mass) / litres
- Mmolarity in mol/L
Molarity Calculatorが結果を出す方法
The Molarity Calculator implements the textbook formula for molarity calculator. Each step the calculator performs is mechanical and deterministic - you can trace the result through the formula by hand and arrive at the same number. For tools where multiple methods exist (e.g., different formulas for area or perimeter, different conventions for rounding), the Molarity Calculator either lets you pick the variant or defaults to the most widely-taught one.
Floating-point arithmetic has well-known quirks (e.g., 0.1 + 0.2 ≠ 0.3 exactly), but for typical problems the result is accurate to far more decimal places than you'll display. Where exactness is critical and inputs are integers or rationals, switch to the relevant exact-arithmetic tool on this site.
Molarity Calculatorを使う場面
- Students at school or college using the Molarity Calculator to check homework, prepare for exams, or build intuition through trial and error.
- Teachers and tutors using the Molarity Calculator as a live demonstration tool - open it on a projector, walk through the inputs, and the answer is visible to everyone.
- Engineers, analysts and developers using the Molarity Calculator for one-off calculations where pulling out a programming language or spreadsheet would be overkill.
- Curious users exploring how a number changes as one input varies - useful for understanding the underlying relationship at an intuitive level.
よくある間違いと落とし穴
- Mixing units. Most math formulas are unit-agnostic; the calculator returns the numbers you give it, so consistency is your responsibility.
- Treating the result as exact when the inputs are approximate. Rounded inputs lead to rounded outputs.
- Misreading the formula. Spending 30 seconds reading the formula above the form removes most of the surprises later.
- Forgetting that some math formulas have domain restrictions - log of a non-positive number, square root of a negative, division by zero - the Molarity Calculator flags these but the underlying meaning is yours to interpret.
このツールを使いこなす
- Try edge-case inputs (zero, very large, negative where applicable) to understand how the calculator behaves at the limits.
- Bookmark the page. The URL is stable and the tool works offline once loaded.
- Use the formula shown above the calculator to verify by hand at least once - it builds confidence in the tool and your understanding.
- Pair this calculator with related math tools on this site to chain calculations together for multi-step problems.
Molarity Calculatorに関するよくある質問
Is the volume the solvent or the solution?
The final solution volume, not the volume of solvent you start with.
What is a 1 M solution?
One mole of solute dissolved to make one litre of solution.
Math in your browser
From simple percentages to scientific notation, statistics, geometry and big-number arithmetic - every common math problem you'd reach for a calculator for, runs in your browser with no installs. The fraction calculator preserves exact rationals, the big-number calculator uses BigInt for hundreds of digits without precision loss, and the scientific calculator's expression evaluator is a hand-written shunting-yard parser (no eval) that supports trig, log, factorial and parentheses.
If you're a student, double-check your work without paying for a graphing calculator. If you're a professional, use these tools as a sanity check on spreadsheet formulas. Every result is shown alongside its formula and inputs, so the math is always auditable.
The Molarity Calculator is part of the Math suite on Online Calculator Tools, alongside 5 related calculators. All tools share the same UI patterns, the same privacy-first rendering (nothing is sent to a server), and the same commitment to showing the formula and assumptions behind every result.