Pine Script to MQL5 converter: what converts, what breaks

Short answer: No Pine Script to MQL5 converter reproduces behavior on its own, because the languages run differently. Pine re-executes on every update of the open bar and rolls its state back, while an MQL5 indicator fills buffers in OnCalculate and an Expert Advisor reacts in OnTick. Syntax maps almost line by line, but timing, seeds and order handling do not, so a port is finished only when its values match the original bar by bar.

Generated code can compile and still be wrong on the open bar, in how its averages start or in which bars it reads. The Python check ran on synthetic data on 5 November 2026; MetaEditor and MT5 were not available, so the MQL5 samples were not compiled or run.

Sending TradingView alerts to MT5 is a bridge, not a port. TradingView's Terms of Use (opens in a new tab) (section 3, read 5 November 2026) license alerts and webhooks for display use only and prohibit using them for automated trading, including through third-party products. Read the terms and take legal advice before building one.

Pine Script vs MQL5: why a converter cannot copy behavior

A converter rewrites syntax, but results change with when the code runs and what happens to its state.

How to convert Pine Script to MQL5: a function map

Most names have a partner; the third column is where a port goes wrong.

Pine Script indicator to MQL5 indicator: a minimal port

Even a one-line Pine indicator becomes a handle, a buffer and an incremental copy in MQL5.

//@version=6
indicator("EMA port check", overlay = true)
length = input.int(20, "Length", 1)
plot(ta.ema(close, length), "EMA")

// Not compiled or run.
#property indicator_chart_window
#property indicator_buffers 1
#property indicator_plots   1
#property indicator_type1   DRAW_LINE
#property indicator_color1  clrDodgerBlue
#property indicator_label1  "EMA"
input int InpLength = 20;
double Line[];
int    handle = INVALID_HANDLE;

int OnInit()
  {
   SetIndexBuffer(0, Line, INDICATOR_DATA);
   handle = iMA(_Symbol, _Period, InpLength, 0, MODE_EMA, PRICE_CLOSE);
   return(handle == INVALID_HANDLE ? INIT_FAILED : INIT_SUCCEEDED);
  }

int OnCalculate(const int rates_total, const int prev_calculated, const int begin, const double &price[])
  {
   if(BarsCalculated(handle) < rates_total)
      return(0);
   int n = (prev_calculated <= 0) ? rates_total : rates_total - prev_calculated + 1;
   return(CopyBuffer(handle, 0, 0, n, Line) < 0 ? 0 : rates_total);
  }

// In an Expert Advisor: act once per bar, on the last closed bar. Not compiled.
// handle: created once in OnInit
datetime last_bar = 0;

void OnTick()
  {
   datetime t = iTime(_Symbol, _Period, 0);
   if(t == 0 || t == last_bar)
      return;
   double v[2];                               // v[0] is bar 2, v[1] is bar 1: oldest comes first
   if(CopyBuffer(handle, 0, 1, 2, v) < 2)
      return;                                 // retry on the next tick
   last_bar = t;                              // only after a good copy
   // your rule here, using closed values only
  }

These samples follow the reference's signatures. An EA sees a closed bar only when the next bar's first tick arrives, so a quiet market delays it.

Why ported values drift: seeds, averages, warm-up

Correct code can still differ: a recursive average remembers its seed, and the platforms load different history.

The v6 reference's example starts ta.ema at the first source value and ta.rma at an SMA of the first length values; MT5's help gives no first EMA value. Two seeds converge at a known rate, since the gap is multiplied by 1 - 2/(N+1) each bar:

Skip at least that many bars before you compare, and check that the MT5 chart, capped by Max. bars in chart in its platform settings (opens in a new tab), holds enough history.

Other gaps never shrink, because the formula differs. On 3,000 synthetic hourly bars (a random walk, seed 7) tested on 5 November 2026, skipping the first 300:

• RSI. Wilder smoothing against plain 14-bar averages: a median gap of 6.02 points, at most 29.08.
• ATR. RMA against SMA of true range: a median gap of 4.01%, at most 24.6%.
• MACD. EMA and SMA signal lines crossed the MACD 229 and 223 times; on 224 bars only one crossed.

These figures show sensitivity, not what either platform computes; where MT5's help is silent, compare numbers or write the Pine formula as a custom indicator. ta.rma and the help's SMMA formula agreed to within floating-point error.

How to check a port: diff both series with a tested script

Compare numbers, not charts, and separate three questions: same bars, same formula, same timing.

TradingView's Help Center describes Download chart data, a CSV of what the chart shows, but section 3 of its Terms of Use licenses data for display only and prohibits processing it. A cleaner test avoids that data: recompute the Pine formula in Python from bars your terminal exports, as in Pine Script to Python, and compare it with the MQL5 buffer, so formula and timing are tested with no feed difference.

import numpy as np
import pandas as pd


def aligned(pine, mql5):          # two series indexed by bar open time
    for s in (pine, mql5):
        if not s.index.is_unique:
            raise ValueError("duplicate bar times: fix the export first")
    return pd.concat([pine.rename("pine"), mql5.rename("mql5")], axis=1).sort_index()


def compare(pine, mql5, warmup, tol):
    if not 0 < tol < np.inf:
        raise ValueError("tol must be finite and above 0")
    both = aligned(pine, mql5)
    missing = int(both.isna().any(axis=1).sum())      # bars only one side has
    both = both.dropna().iloc[warmup:]
    if both.empty:
        raise ValueError("no shared bars after warm-up: check clocks and history")
    gap = (both["pine"] - both["mql5"]).abs()
    lags = pd.Series({k: (both["pine"] - both["mql5"].shift(k)).abs().median() for k in (0, -1, 1)})
    return {"bars": len(both), "missing": missing, "over": int((gap > tol).sum()),
            "max_gap": float(gap.max()), "best_lag": int(lags.idxmin())}


def clock_shift(pine, mql5, hours=range(-14, 15)):
    """Hours to add to the MQL5 stamps; None if no shift or several fit."""
    def hits(h):
        both = aligned(pine, mql5.set_axis(mql5.index + pd.Timedelta(hours=h))).dropna()
        return int((both["pine"] - both["mql5"]).abs().lt(1e-6).sum())
    counts = pd.Series({h: hits(h) for h in hours})
    top = counts[counts == counts.max()]
    return int(top.index[0]) if counts.max() > 0 and len(top) == 1 else None


def ema_from_first(s, n):     # seeded with the first value, as in the reference
    return s.ewm(alpha=2 / (n + 1), adjust=False).mean()


def ema_from_sma(s, n):       # seeded with an n-bar average
    seeded = s.iloc[n - 1:].copy()
    seeded.iloc[0] = s.iloc[:n].mean()
    return seeded.ewm(alpha=2 / (n + 1), adjust=False).mean().reindex(s.index)


rng = np.random.default_rng(7)                        # synthetic hourly closes
idx = pd.date_range("2026-01-05", periods=2000, freq="h")
close = pd.Series(1.10 + rng.normal(0, 0.0008, 2000).cumsum(), index=idx)
noise = pd.Series(rng.normal(0, 0.00005, 2000), index=idx)
pine = ema_from_first(close, 20)
print("seed differs, no warm-up ", compare(pine, ema_from_sma(close, 20), 0, 1e-5))
print("seed differs, 100 skipped", compare(pine, ema_from_sma(close, 20), 100, 1e-5))
print("port reads the open bar  ", compare(pine, pine.shift(-1), 100, 1e-5))
print("other feed, same code    ", compare(pine, ema_from_first(close + noise, 20), 100, 1e-5))
print("clock two hours ahead    ", clock_shift(close, close.set_axis(idx + pd.Timedelta(hours=2))))
print("clock 30 minutes ahead   ", clock_shift(close, close.set_axis(idx + pd.Timedelta(minutes=30))))

Run clock_shift on closes: on hourly bars it would mistake a one-bar timing bug for a one-hour shift. It returned -2 for stamps two hours ahead and None for a 30-minute offset, which a whole-hour search cannot find. Duplicate bar times, an empty overlap and a NaN or infinite tolerance raise errors. Base the tolerance on the symbol's tick size.

Why a Pine strategy and its MQL5 port trade differently

Match the values first: orders add differences no code can remove.

• Fill model. The broker emulator fills from chart data and infers the path inside a bar; MT5's tester help (opens in a new tab) says testing on the broker's real ticks comes closest to real conditions.
• Prices. CTrade::Buy (opens in a new tab) uses the current Ask unless told otherwise, so spread enters a port that the chart price hid.
• Quantities. default_qty_type and contract units become lots, with the broker's minimum and step, and each request needs a valid filling mode.

Read the Pine trade list as in TradingView Strategy Tester and explain each difference. A matching port shows that the code agrees, never that the rules make money, and backtests do not guarantee future results.

When a bridge or a Python port is the better job

Port to MQL5 only if the code must live in the terminal.

Convert only what you may reuse. Under section 22 of TradingView's Terms of Use (read 5 November 2026), an author may choose any license, and a script with none stated is under the Mozilla Public License 2.0; the House Rules (opens in a new tab) ask for permission and credit before reuse. Protected and invite-only code is out of scope: ask the author. This guide gives no strategy or parameter advice.

Leveraged forex carries high risk, and automated orders can lose money quickly. Rules depend on your country, account types and API access vary by broker, and no broker is recommended or ranked here. For readers in Turkey: the Capital Markets Board said on 23 February 2023 (opens in a new tab) that residents may trade leveraged products only through firms it has authorized (Law No. 6362 (opens in a new tab) Articles 99(4) and 109(2)).

For integration work in general, see TradingView automation; naming MetaTrader 5 here does not mean Fincode integrates it or has built on it.

Frequently asked questions

Is there a free online Pine Script to MQL5 converter?

Code generators exist, but none makes the execution models agree: treat output as a draft and compare values bar by bar.

Can I convert Pine Script to MQL4 for MT4?

The same differences apply; MQL4 indicator functions also return values directly instead of handles, and its order functions differ.

Can I convert a protected or invite-only script?

Not without the author: you cannot read the code, and this guide does not cover reconstructing it. Check the license of any open script you reuse.

Why do my MQL5 values differ from TradingView by a small amount?

Usually warm-up or the data feed: skip enough bars for averages to settle, align the clocks and test on one set of bars. A gap that never shrinks points to a different formula.

Sources

• TradingView Pine Script manual: Execution model (rollback, realtime bars) (opens in a new tab)
• TradingView Pine Script v6 reference: ta.ema, ta.rma, ta.rsi (opens in a new tab)
• TradingView Pine Script manual: Other timeframes and data (lookahead, gaps) (opens in a new tab)
• TradingView Pine Script manual: Strategies (broker emulator, reversing positions) (opens in a new tab)
• TradingView: Terms of Use, sections 3 and 22 (opens in a new tab)
• TradingView Help Center: How to export chart data (opens in a new tab)
• TradingView Help Center: MACD (oscillator and signal MA types) (opens in a new tab)
• MQL5 Reference: OnCalculate (opens in a new tab)
• MQL5 Reference: OnTick (opens in a new tab)
• MQL5 Reference: iMA (opens in a new tab)
• MQL5 Reference: CopyBuffer (opens in a new tab)
• MetaTrader 5 Help: Moving Average (SMA, EMA, SMMA formulas) (opens in a new tab)
• MetaTrader 5 Help: MACD (signal line as SMA) (opens in a new tab)
• MetaTrader 5 Help: Average True Range (opens in a new tab)
• SPK: Press notice on unauthorized leveraged trading, 23 February 2023 (Turkish) (opens in a new tab)

This guide is general information about software and markets, not investment, legal or tax advice. Automated trading can lose money, past or backtested performance does not guarantee future results, and the rules that apply depend on your jurisdiction and your exchange's terms. Sources, checks and corrections: see the editorial policy.