Direct answer
“Forex market rate in C” generally means: you want the exchange rate expressed in currency C, for a forex pair (for example, A/B) so it can be compared with a rate shown by another system or source. Because many platforms quote rates using different base/quote conventions, you typically obtain “in C” rates by converting through currency C using consistent rate relationships, not by assuming a single universal number exists in all formats.
Explanation: what you’re actually converting
A forex quote is normally written as Base/Quote. The number tells you how much Quote you receive (or pay) for 1 unit of Base. To express an A/B market rate “in C,” you need a conversion path that lands your result in currency C.
Two common patterns are:
- Direct conversion available: If the market provides the needed A↔C and B↔C relationships, you can transform the A/B value into C by combining those rates.
- Cross-rate construction: If the A/B rate is not directly quoted in the same way, you can compute a cross rate using rates that involve C, provided the inputs are internally consistent.
Mechanics: a reliable way to compute and verify
Use a consistent set of definitions:
- Pick the exact target you want: “How many units of C per 1 unit of A?” or “How many units of C per 1 unit of B?” Those are different.
- Confirm the base/quote direction for every input rate.
- Use one clear conversion path (for example, A→C and B→C) and apply the math consistently.
Then perform independent checks:
- Round-trip check: If you convert A→C and then convert back using the inverse relationships (and the same conventions), you should come back close to the starting value. Large gaps usually indicate direction or conversion-path mistakes.
- Consistency check: Compare the computed “in C” rate to any other source only after aligning (a) base/quote direction, (b) conversion path assumptions, and (c) the time reference. Even if two sources are both “market,” they may not use the same execution model.
Example or checks
Assume you have rates involving currencies A, B, and C. To get the A/B rate expressed relative to C:
- First, translate each needed relationship into the same direction (for example, “C per 1 of X”).
- Next, combine them to produce the target form you requested.
If your result looks implausible (too large or too small), the most frequent causes are:
- You used Base/Quote backwards for one input.
- You mixed conventions (for example, one input effectively represents “mid” while another reflects a different aggregation method).
- You used rates from different moments, so the implied cross rate moved.
Limitations and risks
- No single universal number: “Market rate in C” depends on how the rate is quoted (base/quote) and how the conversion is constructed.
- Spread and quoting conventions: Different providers may show different representations (for example, mid vs. executable pricing), which can change the displayed “in C” number.
- Time mismatch: Forex prices move. If inputs are not from the same timestamp reference, cross-rate results can diverge.
- Rounding: Formatting and rounding can create small but noticeable differences when you compare across sources.
Because there is no single, fixed “in C” value without specifying the quote direction, conversion path, and timing, the safest verification method is to reproduce the conversion yourself using consistent conventions and then compare only after those assumptions match.